QRSTVX, a long squarebar, which passes through the sockets YZ, and carries the stage or frame that holds the objects; this bar may be moved backward or forward, in order to adjust it to the focus by means of the pinion which is at a.
b, A handle furnished with an universal joint, for more conveniently turning the pinion. When the handle is removed, the nut (fig. 27.) may be used in its stead.
de, A brass bar, to support the curved piece KI, and keep the body AB firm and steady.
fg hi, The stage for opaque objects: it fits upon the bar QRST by means of the socket hi, and is brought nearer to or removed farther from the magnifying lens by turning the pinion a: the objects are placed in the front side of the stage (which cannot be seen in this figure) between four small brass plates; the edges of two of these are seen at kl. The two upper pieces of brass are moveable; they are fixed to a plate, which is acted on by a spiral spring, that presses them down, and confines the slider with the objects: this plate, and the two upper pieces of brass, are lifted up by the small nut m.
At the lower part of the stage, there is a semicircular lump of glass n, which is designed to receive the light from the lamp, fig. 29. and to collect and throw it on the concave mirror o, whence it is to be reflected on the object.
The upper part fg rs (fig. 26.) of the opaque stage Microscope takes out, that the stage for transparent objects may be inserted in its place.
Fig. 28. represents the stage for transparent objects; the two legs 5 and 6 fit into the top of the under part rs hi of the stage for opaque objects; 7 is the part which confines or holds the sliders, and through which they are to be moved; 9 and 10 a brass tube, which contains the lenses for condensing the light, and throwing it upon the object; there is a second tube within that, marked 9 and 10, which may be placed at different distances from the object by the pin 11.
When this stage is used as a single microscope, without any reference to the lucernal, the magnifiers, or object lenses, are to be screwed into the hole 12, and to be adjusted to a proper focus by the nut 13.
N. B. At the end AB (fig 26.) of the wooden body there is a slider, which is represented as partly drawn out at A: when quite taken out, three grooves will be perceived; one of which contains a board that forms the end of the box; the next contains a frame with a greyed glass; and the third, or that farthest from the end AB, two large convex lenses.
Fig. 29. represents one of Argand's lamps, which are the most suitable for microscopic purposes, on account of the clearness, the intensity, and the steadiness of the light. The following account of the method of managing them, with other observations, is copied from an account given by Mr Parker with those he sells.
The principle on which the lamp acts, consists in disposing the wick in thin parts, so that the air may come into contact with all the burning fuel; by which means, together with an increase of the current of air occasioned by rarefaction in the glass tube, the whole of the fuel is converted into flame.
The wicks are circular; and, the more readily to regulate the quantity of light, are fixed on a brass collar, with a wire handle, by means of which they are raised or depressed at pleasure.
To fix the wick on, a wooden mandril is contrived, which is tapered at one end, and has a groove turned at the other.
The wick has a selvage at one end, which is to be put foremost on the mandril, and moved up to the groove; then putting the groove into the collar of the wick-holder, the wick is easily pushed forward upon it.
The wick-holder and wick being put quite down in their place, the spare part of the wick should, while dry, be set a-light, and suffered to burn to the edge of the tubes; this will leave it more even than by cutting, and, being black by burning, will be much easier lighted: for this reason, the black should never be quite cut off.
The lamp should be filled an hour or two before it is wanted, that the cotton may imbibe the oil and draw the better.
The lamps which have a reservoir and valve, need no other direction for filling than to do it with a proper trimming pot, carefully observing when they are full; then pulling up the valve by the point, the reservoir, being turned with the other hand, may be replaced without spilling a drop.
Those lamps which fill in the front like a bird-fountain, must be reclined on the back to fill; and this
Microscope should be done gently, that the oil in the burner may return into the body when so placed and filled; if, by being too full, any oil appears above the guard, only move the lamp a little, and the oil will disappear; the lamp may then be placed erect, and the oil will flow to its proper level.
The oil must be of the spermaceti kind, commonly called chamber-oil, which may generally be distinguished by its paleness, transparency, and inoffensive scent: all those oils which are of a red and brown colour, and of an offensive scent, should be carefully avoided, as their glutinous parts clog the lamp, and the impurities in such oil, not being inflammable, will accumulate and remain in the form of a crust on the wick. Seal oil is nearly as pale and sweet as chamber oil; but being of a heavy sluggish quality, is not proper for lamps with fine wicks.
Whenever bad oil has been used, on changing it, the wick must also be changed; because, after having imbibed the coarse particles in its capillary tubes, it will not draw up the fine oil.
To obtain the greatest degree of light, the wick should be trimmed exactly even, the flame will then be completely equal.
There will be a great advantage in keeping the lamp clean, especially the burner and air-tubes; the neglect of cleanliness in lamps is too common: a candlestick is generally cleaned every time it is used, so should a lamp; and if a candlestick is not to be objected to because it does not give light after the candle is exhausted, so a lamp should not be thought ill of, if it does not give light when it wants oil or cotton; but this last has often happened, because the deficiency is less visible.
The glass tubes are best cleaned with a piece of wash leather.
If a fountain-lamp is left partly filled with oil, it may be liable to overflow; this happens by the contraction of the air when cold, and its expansion by the warmth of a room, the rays of the sun, or the heat of the lamp when re-lighted: this accident may be effectually prevented by keeping the reservoir filled, the oil not being subject to expansion like air. On this account, those with a common reservoir are best adapted for microscopic purposes.
To examine Opaque Objects with the Lucernal Microscope. To render the use of this instrument easy, it is usually packed with as many of the parts together as possible: it occupies on this account rather more room, but is much less embarrassing to the observer, who has only three parts to put on after it is taken out of its box, namely, the guide for the eye, the stage, and the tube with its magnifier.
But to be more particular: Take out the wooden slider A (fig. 26.), then lift out the cover and the grey glass from their respective grooves under the slider A.
Put the end N of the guide for the eye LMM into its place, so that it may stand in the position which is represented in this figure.
Place the socket which is at the bottom of the opaque stage, on the bar QXT, so that the concave mirror o may be next the end DE of the wooden body.
Screw the tubes PO into the end DE. The magnifier which you intend to use is to be screwed on the end O of these tubes.
The handle G, or the milled nut fig. 27. must be placed on the square end of the pinion a.
Place the lamp lighted before the glass lamp n, and the object you intend to examine between the spring-plates of the stage; and the instrument is ready for use.
In all microscopes there are two circumstances which must be particularly attended to: first, the modification of the light, or the proper quantity to illuminate the object; secondly, the adjustment of the instrument to the focus of the glasses and eye of the observer. In the use of the lucernal microscope there is a third circumstance, which is, the regulation of the guide for the eye.
1. To throw the light upon the object. The flame of the lamp is to be placed rather below the centre of the glass lamp n, and as near it as possible; the concave mirror o must be so inclined and turned as to receive the light from the glass lamp, and reflect it thence upon the object; the best situation of the concave mirror and the flame of the lamp depends on a combination of circumstances, which a little practice will discover.
2. To regulate the guide for the eye, or to place the centre of the eye-piece L so that it may coincide with the focal point of the lenses and the axis of vision: Lengthen and shorten the tubes MN, by drawing out or pushing in the inner tube, and raising or depressing the eye-piece ML, till you find the large lens (which is placed at the end AB of the wooden body) filled by an uniform field of light, without any prismatic colours round the edge; for till this piece is properly fixed, the circle of light will be very small, and only occupy a part of the lens: the eye must be kept at the centre of the eye-piece L, during the whole of the operation; which may be rendered somewhat easier to the observer, on the first use of the instrument, if he hold a piece of white paper parallel to the large lens, removing it from or bringing it nearer to them till he find the place where a lucid circle, which he will perceive on the paper, is brightest and most distinct; then he is to fix the centre of the eye-piece to coincide with that spot; after which a very small adjustment will set it perfectly right.
3. To adjust the lenses to their focal distance. This is effected by turning the pinion a, the eye being at the same time at the eye-piece L. The grey glass is often placed before the large lenses, while regulating the guide for the eye, and adjusting for the focal distance.
If the observer, in the process of his examination of an object, advance rapidly from a shallow to a deep magnifier, he will save himself some labour by pulling out the internal tube at O.
The upper part fg r s of the stage is to be raised or lowered occasionally, in order to make the centre of the object coincide with the centre of the lens at O.
To delineate objects, the grey glass must be placed before the large lenses; the picture of the object will be formed on this glass, and the outline may be accurately taken by going over the picture with a pencil.
The
Microscope The opaque part may be used in the day-time without a lamp, provided the large lenses at AB are screened from the light.
To use the Lucernal Microscope in the examination of Transparent Objects. The instrument is to remain as before: the upper part fg of the opaque stage must be removed, and the stage for transparent objects, represented at fig. 28. put in its place; the end g to be next the lamp.
Place the greyed glass in its groove at the end AB, and the objects in the slider-holder at the front of the stage; then transmit as strong a light as you are able on the object, which you will easily do by raising or lowering the lamp.
The object will be beautifully depicted on the grey glass: it must be regulated to the focus of the magnifier, by turning the pinion a.
The object may be viewed either with or without the guide for the eye. A single observer will see an object to the greatest advantage by using this guide, which is to be adjusted as we have described above. If two or three wish to examine the object at the same time, the guide for the eye must be laid aside.
Take the large lens out of the groove, and receive the image on the grey glass; in this case, the guide for the eye is of no use: if the grey glass be taken away, the image of the object may be received on a paper screen.
Take out the grey glass, replace the large lenses, and use the guide for the eye; attend to the foregoing directions, and adjust the object to its proper focus. You will then see the object in a blaze of light almost too great for the eye, a circumstance that will be found very useful in the examination of particular objects. The edges of the object in this mode will be somewhat coloured: but as it is only used in this full light for occasional purposes, it has been thought better to leave this small imperfection, than, by remedying it, to sacrifice greater advantages; the more so, as this fault is easily corrected, and a new and interesting view of the object is obtained, by turning the instrument out of the direct rays of light, and permitting them to pass through only in an oblique direction, by which the upper surface is in some degree illuminated, and the object is seen partly as opaque, partly as transparent. It has been already observed, that the transparent objects might be placed between the slider-holders of the stage for opaque objects, and then be examined as if opaque.
Some transparent objects appear to the greatest advantage when the lens at g to is taken away; as, by giving too great a quantity of light, it renders the edges less sharp.
The variety of views which may be taken of every object by means of the improved lucernal microscope, will be found to be of great use to an accurate observer: it will give him an opportunity of correcting or
confirming his discoveries, and investigating those parts Microscope in one mode which are invisible in another.
To throw the image of transparent objects on a screen, as in the solar microscope. It has been long a microscopical desideratum, to have an instrument by which the image of transparent objects might be thrown on a screen, as in the common solar microscope: and this not only because the sun is so uncertain in this climate, and the use of the solar microscope requires confinement in the finest part of the day, when time seldom hangs heavy on the mind; but as it also affords an increase of pleasure, by displaying its wonders to several persons at the same instant, without the least fatigue to the eye.
This purpose is now effectually answered, by affixing the transparent stage of the lucernal to a lanthorn, with one of Argand's lamps.—The lamp is placed within the lanthorn, and the end g to of the transparent stage is screwed into a female screw, which is rivetted in the sliding part of the front of the lanthorn; the magnifying lenses are to be screwed into the hole represented at 12, and they are adjusted by turning the milled nut. The quantity of light is to be regulated by raising and lowering the sliding-plate or the lamp.
Apparatus which usually accompanies the improved Lucernal Microscope. The stage for opaque objects, with its semicircular lump of glass, and concave mirror. The stage for transparent objects, which fits on the upper part of the foregoing stage. The sliding tube, to which the magnifiers are to be affixed: one end of these is to be screwed on the end D of the wooden body; the magnifier in use is to be screwed to the other end of the inner tube. Eight magnifying lenses: these are so constructed, that they may be combined together, and thus produce a very great variety of magnifying powers. A fish-pan, such as is represented at I. A steel wire I, with a pair of nippers at one end, and a small cylinder of ivory I at the other. A slider of brass N, containing a flat glass slider, and a brass slider into which are fitted some small concave glasses. A pair of forceps. Six large and six small ivory sliders, with transparent objects. Fourteen wooden sliders, with four opaque objects in each slider; and two spare sliders. Some capillary tubes for viewing small animalcula.
Ingenious men seldom content themselves with an instrument under one form; hence such a variety of microscopes, hence many alterations in the Lucernal Microscope. Mr Adams himself, we understand, has fitted up this last in a great many different ways; and it is reasonable to think that no person is more likely to give it every improvement of which it is susceptible. Of the alterations by other hands we shall only particularise one, made by Mr Jones of Holborn (a), whose description is as follows:
A, represents a portion of the top of the mahogany box
(a) We trust the reader will never consider any paragraph wherein the name of an instrument-maker or other artist is inserted, as a recommendation of those artists by the editors of this work. In the course of a pretty extensive correspondence, they have been favoured with very liberal communications from various artists, for which they are greatly indebted to them: the inserting their names in this work is therefore to be considered as a grateful acknowledgment from the editors for favours conferred on them,—not as a testimonial
Microscope box in which it packs, to preserve it steady; it slides in a dove-tail groove withinside, a similar groove to which is cut in the top of the box A; so that when the instrument is to be used, it is slipped out of the box withinside, and then slipped into the groove at top ready for use, almost instantly, as shown in the figure. The adjustment of the objects is at the stage E; for the right focal distance is readily and conveniently made by turning the long screw-rod BB, which goes thro' the two pillars supporting the box, and works in the base of the brass stage E; which base is also dove-tailed, so as to have a regular and steady motion in another brass basis that supports it. In this instrument, therefore, the pyramidal box does not move; but the stage part only, which, from its small weight, moves in the most agreeable and steady manner. While observing the image of the object upon the glass through the sight-hole at G, the object may be moved or changed by only turning the rack-work and pinion applied to the stage, by means of the handle D, for that purpose. By this contrivance you have no occasion to change your position during the view of the objects upon one of the sliders. This motion changes the objects horizontally only; and as they are generally placed exactly in one line, it answers all the purposes for which this motion is intended very well. But it may sometimes happen that the observer would wish to alter the vertical position of the object; to perform which there is another plane rod at F, that acts simply as a lever for this purpose, and moves the sliding part of the stage E vertically either upwards or downwards.
Thus, without altering his position, the observer may investigate all parts of the objects in the most satisfactory manner. Rack-work and pinion might be applied to the stage for the vertical motion also; but as it would materially enhance the expence, it is seldom applied. The brass work at the handle of D contains a Hooke's universal joint.
The brilliancy of the images of the objects shown upon the large lenses at the end of the box, being very frequently so great as to dazzle the eyes, Mr Jones applies a slight tinge of blue, green, and other coloured glass, to the sight-hole at G, which softens this glare, and casts an agreeable hue upon the objects.
Description of those Parts of a Microscopical Apparatus, common to most Instruments, which are delineated at fig. 31.
A and B represent the brass cells which contain the magnifiers belonging to the different kinds of compound microscopes. The magnifiers are sometimes contained in a slider like that which is delineated at S (fig. 24). The lenses of A and B are confined by a small cap; on unscrewing this, the small lens may be taken out and cleaned. The magnifiers A of the lucernal microscope are so contrived, that any two of them may be screwed together, by which means a considerable variety of magnifying power is obtained.
To get at the lenses in the slider S (fig. 24.), take out the two screws which hold on the cover.
C, represents the general form of the slider-holder. Microscope It consists of a cylindrical tube, in which an inner tube is forced up by a spring. It is used to receive the ivory or any other slider, in which the transparent objects are placed; these are to be slid between the two upper plates: the hollow part in one of the plates is designed for the glass tubes.
D, the condensing lens and its tube, which fits into the slider-holder C, and may be moved up and down in it. When this piece is pushed up as far as it will go, it condenses the light of a candle, which is reflected on it by the plain mirror of the compound microscope, and spreads it uniformly over the object; in this case it is best adapted to the shallowest magnifiers. If the deeper lenses are used, it should be drawn down, or rather removed further from the object, that it may concentrate the light in a small compass, and thus render it more dense. The condensing lens is sometimes fitted up differently; but the principle being the same, it will be easy to apply it to use notwithstanding some variations in the mechanism.
E, a brass cone. It fixes under the slider-holder, and is used to lessen occasionally the quantity of light which comes from the mirror to any object.
F, a box with two flat glasses, which may be placed at different distances from each other in order to confine a small living insect.
G, a small brass box to hold the silver speculum H.
H, a small silver concave speculum, designed to reflect the light from the mirror on opaque objects; it should only be used with the shallow magnifiers. It is applied in different ways to the compound microscope; sometimes to a tube similar to that represented at X, which slides on the lower part of the body; sometimes it is screwed into the ring of the piece Q; the pin of this generally fits into one of the holes in the stage. When this speculum is used, the slider-holder should be removed.
I, a fish-pan, whereon a small fish may be fastened, in order to view the circulation of the blood: its tail is to be spread across the oblong hole at the smallest end, and tied fast by means of the ribbon fixed thereto, by showing the knob which is on the back of it through the slit made in the stage; the tail of the fish may be brought under the lens which is in use.
K, a cylindrical piece, intended for the solar opaque microscope: by pulling back the spiral spring, smaller or larger objects may be confined in it.
L, A pair of triangular nippers for taking hold of and confining a large object.
M, a long steel wire, with a small pair of pliers at one end and a steel point at the other: the wire slips backwards or forwards in a spring tube, which is affixed to a joint, at the bottom of which is a pin to fit one of the holes in the stage; this piece is used to confine small objects.
N, A small ivory cylinder that fits on the pointed end of the steel wire L; it is designed to receive opaque objects. Light-coloured ones are to be stuck on the dark side, and vice versa.
O, a convex lens, which fits to the stage by means of
Microscope of the long pin adhering to it. This piece is designed to collect the light from the sun or a candle, and to throw them on any object placed on the stage; but it is very little used at present.
N, a brass slider, into which is fitted a flat piece of glass, and a brass slider containing four small glasses, one or two of them concave, the others flat; it is designed to confine small living objects, and when used is to be placed between the two upper plates of the slider-holder.
O, a glass tube to receive a small fish, &c.
P, represents one of the ivory sliders, wherein objects are placed between two pieces of talc, and confined by a brass ring.
Q, a piece to hold the speculum H: this piece is generally fitted to the microscope represented at fig. 12.
R, a pair of forceps, to take up any occasional object.
S, a camel's hair pencil to brush the dust off the glasses; the upper part of the quill is scooped out, to take up a drop of any fluid, and place it on either of the glasses for examination.
T, an instrument for cutting thin transverse sections of wood. It consists of a wooden base, which supports four brass pillars; on the top of the pillars is placed a flat piece of brass, near the middle of which there is a triangular hole.
A sharp knife, which moves in a diagonal direction, is fixed on the upper side of the afore-mentioned plate, and in such a manner that the edge always coincides with the surface thereof.
The knife is moved backwards and forwards by means of the handle a. The piece of wood is placed in the triangular trough which is under the brass plate, and is to be kept steady therein by a milled screw which is fitted to the trough; the wood is to be pressed forward for cutting by the micrometer screw b.
The pieces of wood should be applied to this instrument immediately on being taken out of the ground, or else they should be soaked for some time in water, to soften them so that they may not hurt the edge of the knife.
When the edge of the knife is brought in contact with the piece of wood, a small quantity of spirits of wine should be poured on the surface of the wood, to prevent its curling up; it will also make it adhere to the knife, from which it may be removed by pressing a piece of blotting paper on it.
y, An appendage to the cutting engine, which is to be used instead of the micrometer screw, being preferred to it by some. It is placed over the triangular hole, and kept flat down upon the surface of the brass plate, while the piece of wood is pressed against a circular piece of brass which is on the under side of it. This circular piece of brass is fixed to a screw, by which its distance from the flat plate on which the knife moves may be regulated.
z, An ivory box, containing at one end spare talc for the ivory sliders, and at the other spare rings for pressing the tals together and confining them to the slider.
AFTER what has been related of Microscopes, they cannot be said to be complete without the valuable
addition of a micrometer; for the use and advantages Microscope of which, see the article MICROMETER.
HAVING presented our readers with descriptions of the various microscopes generally used, we think it our duty to point out to them those which we conceive to be best calculated to answer the purposes of science. The first which presents itself to our mind is that of Ellis: It is better adapted, than any other portable microscope, to the purpose of general observation; simple in its construction, and general in its application. To those who prefer a double microscope, we should recommend that figured in Plate CCXCVIII. (12.) If opaque objects, as insects, &c. be subjects of investigation, the Lucernal Microscope claims the preference: but if amusement alone guides the choice, the Solar Microscope must be fixed upon.
We shall now proceed to explain some necessary particulars respecting the method of using microscopes; after which, we shall subjoin an enumeration of the principal objects discovered or elucidated by their means. On this subject Mr Adams, in his Essay on the Microscope, has been very copious; with a view, as he informs us, to remove the common complaint made by Mr Baker, "that many of those who purchase microscopes are so little acquainted with their general and extensive usefulness, and so much at a loss for objects to examine by them, that after diverting their friends some few times with what they find in the sliders which generally accompany the instrument, or perhaps with two or three common objects, the microscope is laid aside as of little further value; whereas no instrument has yet appeared in the world capable of affording so constant, various, and satisfactory an entertainment to the mind."
1. In using the microscope, there are three things necessary to be considered. (1.) The preparation and adjustment of the instrument itself. (2.) The proper quantity of light, and the best method of adapting it to the object. (3.) The method of preparing the objects, so that their texture may be properly understood.
1. With regard to the microscope itself, the first thing necessary to be examined is, whether the glasses be clean or not: if they are not so, they must be wiped with a piece of soft leather, taking care not to soil them afterwards with the fingers; and, in replacing them, care must be taken not to place them in an oblique situation. We must likewise be careful not to let the breath fall upon the glasses, nor to hold that part of the body of the instrument where the glasses are placed with a warm hand; because thus the moisture expelled by the heat from the metal will condense upon the glass, and prevent the object from being distinctly seen. The object should be brought as near the centre of the field of view as possible; for there only it will be exhibited in the greatest perfection. The eye should be moved up and down from the eye-glass of a compound microscope, till the situation is found where the largest field and most distinct view of the object are to be had: but every person ought to adjust the microscope to his own eye, and not to depend upon the situation it was placed in by another. A small magnifying power should
always
Microscope always be begun with; by which means the observer will best obtain an exact idea of the situation and connection of the whole; and will of consequence be less liable to form any erroneous opinion when the parts are viewed separately by a lens of greater power. Objects should also be examined first in their most natural position: for if this be not attended to, we shall be apt to form very inadequate ideas of the structure of the whole, as well as of the connection and use of the parts. A living animal ought to be as little hurt or discomposed as possible.
From viewing an object properly, we may acquire a knowledge of its nature: but this cannot be done without an extensive knowledge of the subject, much patience, and many experiments; as in a great number of cases the images will resemble each other, though derived from very different substances. Mr Baker therefore advises us not to form an opinion too suddenly after viewing a microscopical object; nor to draw our inferences till after repeated experiments and examinations of the object in many different lights and positions; to pass no judgment upon things extended by force, or contracted by dryness, or in any manner out of a natural state, without making suitable allowances. The true colour of objects cannot be properly determined by very great magnifiers; for as the pores and interstices of an object are enlarged according to the magnifying power of the glasses made use of, the component particles of its substance will appear separated many thousand times farther asunder than they do to the naked eye: hence the reflection of the light from these particles will be very different, and exhibit different colours. It is likewise somewhat difficult to observe opaque objects; and as the apertures of the larger magnifiers are but small, they are not proper for the purpose. If an object be so very opaque, that no light will pass through it, as much as possible must be thrown upon the upper surface of it. Some consideration is likewise necessary in forming a judgment of the motion of living creatures, or even of fluids, when seen through the microscope; for as the moving body, and the space wherein it moves, are magnified, the motion will also be increased.
2. On the management of the light depends in a great measure the distinctness of the vision: and as, in order to have this in the greatest perfection, we must adapt the quantity of light to the nature of the object and the focus of the magnifier, it is therefore necessary to view it in various degrees of light. In some objects, it is difficult to distinguish between a prominence and a depression, a shadow or a black stain; or between a reflection of light and whiteness, which is particularly observable in the eye of the libella and other flies: all of these appearing very different in one position from what they do in another. The brightness of an object likewise depends on the quantity of light, the distinctness of vision, and on regulating the quantity to the object; for some will be in a manner lost in a quantity of light scarce sufficient to render another visible.
There are various ways in which a strong light may be thrown upon objects; as by means of the sun and a convex lens. For this purpose, the microscope is to be placed about three feet from a southern window;
then take a deep convex lens, mounted on a semicircle Microscope and stand, so that its position may easily be varied: place this lens between the object and the window, so that it may collect a considerable number of solar rays, and refract them on the object or the mirror of the microscope. If the light thus collected from the sun be too powerful, it may be lessened by placing a piece of oiled paper, or a piece of glass lightly greyed, between the object and lens. Thus a proper degree of light may be obtained, and diffused equally all over the surface of an object: a circumstance which ought to be particularly attended to; for if the light be thrown irregularly upon it, no distinct view can be obtained. If we mean to make use of the solar light, it will be found convenient to darken the room, and to reflect the rays of the sun on the abovementioned lens by means of the mirror of a solar microscope fixed to the window-shutter: for thus the observer will be enabled to preserve the light on his object, notwithstanding the motion of the sun. But by reason of this motion, and the variable state of the atmosphere, solar observations are rendered both tedious and inconvenient: whence it will be proper for the observer to be furnished with a large tin lantern, formed something like the common magic lantern, capable of containing one of Argand's lamps. This, however, ought not to be of the fountain kind, lest the rarefaction of the air in the lantern should force the oil over. There ought to be an aperture in the front of the lantern, which may be moved up and down, and be capable of holding a lens; by which means a pleasant and uniform as well as strong light may easily be procured. The lamp should likewise move on a rod, so that it may be easily raised or depressed. This lantern may likewise be used for many other purposes; as viewing of pictures, exhibiting microscopic objects on a screen, &c. A weak light, however, is best for viewing many transparent objects: among which we may reckon the prepared eyes of flies, as well as the animalcules in fluids. The quantity of light from a lamp or candle may be lessened by removing the microscope to a greater distance from them, or by diminishing the strength of the light which falls upon the objects. This may very conveniently be done by pieces of black paper with circular apertures of different sizes, and placing a larger or smaller one upon the reflecting mirror, as occasion may require. There is an oblique situation of the mirrors, which makes likewise an oblique reflection of the light easily discovered by practice, (but for which no general rule can be given in theory); and which will exhibit an object more distinctly than any other position, showing the surface, as well as those parts through which the light is transmitted. The light of a lamp or candle is generally better for viewing microscopic objects than day-light; it being more easy to modify the former than the latter, and to throw it upon the objects with different degrees of density.
3. With regard to the preparation of objects, Swammerdam has, in that particular, excelled almost all other investigators who either preceded or have succeeded him. He was so assiduous and indefatigable, that neither difficulty nor disappointment could make the least impression upon him; and he never abandoned the pursuit of any object until he had obtained
Microscope tained a satisfactory idea of it. Unhappily, however, the methods he made use of in preparing his objects for the microscope are now entirely unknown. Dr Boerhaave examined with the strictest attention all the letters and manuscripts of Swammerdam which he could find; but his researches were far from being successful. The following particulars, however, have thus come to the knowledge of the public.
For dissecting of small insects, Swammerdam had a brass table made by S. Muschenbroek, to which were affixed two brass arms moveable at pleasure to any part of it. The upper part of these vertical arms was constructed in such a manner as to have a slow vertical motion; by which means the operator could readily alter their height as he saw convenient. One of these arms was to hold the minute objects, and the other to apply the microscope.
The lenses of Swammerdam's microscopes were of various sizes as well as foci; but all of them the best that could be procured, both for the transparency of the glass and the fineness of the workmanship. His observations were always begun with the smallest magnifiers, from which he proceeded to the greatest; but in the use of them, he was so exceedingly dexterous, that he made every observation subservient to that which succeeded it, and all of them to the confirmation of each other, and to the completing of the description. His chief art seems to have been in constructing scissars of an exquisite fineness, and making them very sharp. Thus he was enabled to cut very minute objects to much more advantage than could be done by knives and lancets; for these, though ever so sharp and fine, are apt to disorder delicate substances by displacing some of the filaments, and drawing them after them as they pass through the bodies; but the scissars cut them all equally. The knives, lancets, and styles he made use of in his dissections, were so fine that he could not see to sharpen them without the assistance of a magnifying glass; but with these he could dissect the intestines of bees with the same accuracy that the best anatomists can do those of large animals. He made use also of very small glass tubes no thicker than a bristle, and drawn to a very fine point at one end, but thicker at the other. These were for the purpose of blowing up, and thus rendering visible the smallest vessels which could be discovered by the microscope; to trace their courses and communications, or sometimes to inject them with coloured liquors.
Swammerdam sometimes made use of spirit of wine, water, or oil of turpentine, for suffocating the insects he wished to examine; and would preserve them for a time in these liquids. Thus he kept the parts from putrefying, and gave them besides such additional strength and firmness, as rendered the dissections much more easy than they would otherwise have been. Having then divided the body transversely with the scissars, and made what observations he could without farther dissection, he proceeded to extract the intestines carefully with very fine instruments, to wash away the fat in the like careful manner; and thus to put the parts into such a state as would best expose them to view; but these operations are best performed while the insects are in their nymphal state.
VOL. XI. Part II.
Microscope Sometimes the delicate viscera of the insects, after Microscope having been suffocated as abovementioned, were put into water; after which, having shaken them gently, he procured an opportunity of examining them, especially the air vessels, which last he could thus separate entire from all the other parts, to the admiration of all who beheld them; as these vessels cannot be distinctly seen in any other manner, or indeed in any way whatever, without injuring them. Frequently also he injected water with a syringe to cleanse the parts thoroughly, after which he blew them up with air and dried them; thus rendering them durable, and fit for examination at a proper opportunity. Sometimes he made very important discoveries, by examining insects which he had preserved for several years in balsam. Other insects he punctured with a very fine needle; and after squeezing out all their moisture through the holes made in this manner, he filled them with air, by means of very slender glass tubes; then dried them in the shade; and lastly anointed them with oil of spike in which a little rosin had been dissolved; and by which means they, for a long time, retained their proper forms. He was likewise in possession of a singular secret, by which he could preserve the limbs of insects as limber and perspicuous as ever they had been. He used to make a small puncture or incision in the tails of worms; and after having with great caution squeezed out all the humours, as well as great part of the viscera, he injected them with wax in such a manner as to give them the appearance of living creatures in perfect health. He found that the fat of all insects was entirely dissolvable in oil of turpentine; by which means he was enabled plainly to discern the viscera; though, after this dissolution, it was necessary to cleanse and wash them frequently in clean water. In this manner he would frequently have spent whole days in the preparation of a single caterpillar, and cleansing it from its fat, in order to discover the true situation of the insect's heart. He had a singular dexterity in stripping off the skins of caterpillars that were on the point of spinning their cones. This was done by letting them drop by their threads into scalding water, and then suddenly withdrawing them. Thus the epidermis peeled off very easily; and, when this was done, he put them into distilled vinegar and spirit of wine mixed together in equal proportions; which, by giving a due degree of firmness to the parts, gave him an opportunity of separating them with very little trouble from the exuviae, without any danger to the internal parts. Thus the nymph could be shown to be wrapped up in the caterpillar and the butterfly in the nymph; and there is little doubt that those who look into the works of Swammerdam, will be amply recompensed, whether they consider the unexampled labour or the piety of the author.
M. Lyonet, a late eminent naturalist, usually drowned the insects he designed to examine; by which means he was enabled to preserve both the softness and transparency of the parts. According to him, the insect, if very small, viz. one tenth of an inch, or little more, in length, should be dissected on a glass somewhat concave. If it should be suspected that the insect will putrefy by keeping for a few days, spirit of wine diluted with water must be substituted instead of pure water. The insect must be suffered to dry; after which it may
Microscope be fastened by a piece of soft wax, and again covered with water.—Larger objects should be placed in a trough of thin wood; and for this purpose the bottom of a common chip-box will answer very well; only surrounding the edge of it with soft wax, to keep in the water or other fluid employed in preserving the insect. The body is then to be opened; and if the parts are soft like those of a caterpillar, they should be turned back, and fixed to the trough by small pins, which ought to be set by a small pair of nippers. At the same time, the skin being stretched by another pair of finer forceps, the insect must be put into water, and dissected therein, occasionally covering it with spirit of wine. Thus the subject will be preserved in perfection, so that its parts may be gradually unfolded, no other change being perceived than that the soft elastic parts become stiff and opaque, while some others lose their colour.
The following instruments were made use of by M. Lyonet, in his dissection of the Chenille de Saul. A pair of scissors as small as could be made, with long and fine arms: A pair of forceps, with their ends so nicely adjusted, that they could easily lay hold of a spider's thread, or a grain of sand: Two fine steel needles fixed in wooden handles, about two inches and three quarters in length; which were the most generally useful instruments he employed.
Dr Hooke, who likewise made many microscopic observations, takes notice, that the common ant or pismire is much more troublesome to draw than other insects, as it is extremely difficult to get the body in a quiet natural posture. If its feet be fettered with wax or glue, while the animal remains alive, it so twists its body, that there is no possibility of gaining a proper view of it; and if it be killed before any observation is made, the shape is often spoiled before it can be examined. The bodies of many minute insects, when their life is destroyed, instantly shrivel up; and this is observable even in plants as well as insects, the surface of these small bodies being affected by the least change of air; which is particularly the case with the ant. If this creature, however, be dropped into rectified spirit of wine, it will instantly be killed; and when it is taken out, the spirit of wine evaporates, leaving the animal dry, and in its natural posture, or at least in such a state that it may easily be placed in whatever posture we please.
Parts of Insects. The wings, in many insects, are so transparent, that they require no previous preparation; but some of those that are folded up under elytra or cases, require a considerable share of dexterity to unfold them; for these wings are naturally endowed with such a spring, that they immediately fold themselves again, unless care be taken to prevent them. The wing of the earwig, when expanded, is of a tolerable size, yet is folded up under a case not one eighth part of its bulk; and the texture of this wing renders it difficult to be unfolded. This is done with the least trouble immediately after the insect is killed. Holding then the creature by the thorax, between the finger and thumb, with a blunt-pointed pin endeavour gently to open it, by spreading it over the fore-finger, and at the same time gradually sliding the thumb over it. When the wing is sufficiently expanded, separate it from the insect by a sharp
knife or a pair of scissors. The wing should be preserved for some time between the thumb and finger before it be removed; it should then be placed between two pieces of paper, and again pressed for at least an hour; after which time, as there will be no danger of its folding up any more, it may be put between the tales, and applied to the microscope. Similar care is requisite in displaying the wings of the notonecta and other water-insects, as well as most kinds of grylli.
The minute scales or feathers, which cover the wings of moths or butterflies, afford very beautiful objects for the microscope. Those from one part of the wing frequently differ in shape from such as are taken from other parts; and near the thorax, shoulder, and on the fringes of the wings, we generally meet with hair instead of scales. The whole may be brushed off the wing, upon a piece of paper, by means of a camel's-hair pencil; after which the hairs can be separated with the assistance of a common magnifying glass.
It is likewise a matter of considerable difficulty to dissect properly the proboscis of insects, such as the gnat, tabanus, &c. and the experiment must be repeated a great number of times before the structure and situation of the parts can be thoroughly investigated, as the observer will frequently discover in one what he could not in another. The collector of the bee, which forms a very curious object, ought to be first carefully washed in spirit of turpentine; by which means it will be freed from the unctuous matter adhering to it: when dry, it is again to be washed with a camel's-hair pencil to disengage and bring forward the small hairs which form part of this microscopic beauty. The best method of managing the stings of insects, which are in danger of being broken by reason of their hardness, is to soak the case and the rest of the apparatus for some time in spirit of wine or turpentine; then lay them on a piece of paper, and with a blunt knife draw out the sting, holding the sheath with the nail of the finger or any blunt instrument; but great care is necessary to preserve the feelers, which when cleaned add much to the beauty of the object. The beard of the lepas antifer is to be soaked in clean soft water, frequently brushing it while wet with a camel's-hair pencil: after it is dried, the brushing must be repeated with a dry pencil to disengage and separate the hairs, which are apt to adhere together.
To view to advantage the fat, brains, and other similar substances, Dr Hooke advises to render the surface smooth, by pressing it between two plates of thin glass, by which means the matter will be rendered much thinner and more transparent: without this precaution, it appears confused, by reason of the parts lying too thick upon one another. For muscular fibres, take a piece of the flesh, thin and dry; moisten it with warm water, and after this is evaporated the vessels will appear more plain and distinct; and by repeated macerations they appear still more so. The exuviae of insects afford a pleasing object, and require but little preparation. If bent or curled up, they will become so relaxed by being kept a few hours in a moist atmosphere, that you may easily extend them to their natural positions; or the steam of warm water will answer the purpose very well.
The eyes of insects in general form very curious and
Microscope and beautiful objects. Those of the libellula and other flies, as well as of the lobster, &c. must first be cleaned from the blood, &c. after which they should be soaked in water for some days: one or two skins are then to be separated from the eye, which would be otherwise too opaque and confused; but some care is requisite in this operation; for if the skin be rendered too thin, it is impossible to form a proper idea of the organization of the part. In some substances, however, the organization is such, that by altering the texture of the part, we destroy the objects which we wish to observe. Of this sort are the nerves, tendons, muscular fibres, many of which are viewed to most advantage when floating in some transparent fluid. Thus very few of the muscular fibres can be discovered when we attempt to view them in the open air, though great numbers may be seen if they be placed in water or oil. By viewing the thread of a ligament in this manner, we find it composed of a vast number of smooth round threads lying close together. Elastic objects should be pulled or stretched out while they are under the microscope, that the texture and nature of those parts, the figure of which is altered by being thus pulled out, may be more fully discovered.
Other objects. To examine bones by the microscope, they should first be viewed as opaque objects; but afterwards, by procuring thin slices of them, they may be viewed as transparent. The sections should be cut in all directions, and be well washed and cleaned; and in some cases maceration will be useful, or the bones may be heated red hot in a clear fire, and then taken out; by which means the bony cells will appear more conspicuous. The pores of the skin may be examined by cutting off a thin slice off the upper skin with a razor, and then a second from the same place; applying the latter to the microscope. The lizard, guana, &c. have two skins, one very transparent, the other thicker and more opaque; and, separating these two, you obtain very beautiful objects.
To view the scales of fish to advantage, they ought to be soaked in water for a few days, and then carefully rubbed to clean them from the skin and dirt which may adhere to them. The scales of the eel are a great curiosity; and the more so, as this creature was not known to have any scales till they were discovered by the microscope. The method of discovering them is this. Take a piece of the skin of an eel from off its side, and spread it while moist on a piece of glass, that it may dry very smooth: when thus dried, the surface will appear all over dimpled or pitted by the scales, which lie under a sort of cuticle or thin skin; which may be raised with the sharp point of a penknife, together with the scales, which will then easily slip out; and thus we may procure as many as we please.
The leaves of many trees, as well as of some plants, when dissected, form a very agreeable object. In order to dissect them, take a few of the most perfect leaves you can find, and place them in a pan with clean water. Let them remain there three weeks, or a month, without changing the water; then take them up; and if they feel very soft, and almost rotten, they are sufficiently soaked. They must then be laid on a flat board, and holding them by the stalk, draw the
edge of a knife over the upper side of the leaf, which Microscope will take off most of the skin. Then turn the leaf, and do the same with the under side; and when the skin is taken off on both sides, wash out the pulpy matter, and the fibres will be exhibited in a very beautiful manner. The leaf may be slit into two parts, by splitting the stalk; and the skins peeled from the fibres will also make a good object. This operation is best performed in the autumn: the fibres of the leaves are much stronger at that season, and less liable to be broken.—The internal structure of shells may be observed by grinding them down on a hone: and all ores and minerals should be carefully washed and brushed with a small brush to remove any fordes that may adhere to them.
To view the circulation of the blood, we must observe living animals of the most transparent kind.—A small eel is sometimes used for this purpose; in which case it must be cleaned from the slime naturally adhering to it; after which it may be put into a tube filled with water, where it can be viewed in a satisfactory manner. The tail of any other small fish may be viewed in the same manner, or put upon a slip of flat glass, and thus laid before the microscope. By filling the tube with water when an eel is made use of, we prevent in a great measure the sliminess of the animal from foiling the glass.
The particles of the blood form a very curious object, and have been carefully viewed by different philosophers; who, nevertheless, differ from one another very much in their accounts of them. The best method of viewing these is to take a small drop of blood when warm, and spread it as thin as possible upon a flat piece of glass. By diluting it a little with warm water, some of the large globules will be separated from the smaller, and many of them subdivided; or a small drop of blood may be put into a capillary glass-tube, and then placed before the microscope. Mr Baker advises warm milk as proper to be mixed with the blood; but Mr Hewson, who is accounted the most accurate observer, diluted the blood with that fluid which undoubtedly is more natural to it, viz. its own serum: by this method he could preserve the small particles entire, and view them distinctly; and thus he found that they were not globular, as had been imagined by other anatomists, but flat. Having shaken a piece of the crassamentum of the blood in serum till the latter became a little coloured, he spread it with a soft hair pencil on a piece of thin glass, which he placed under the microscope, in such a manner as not to be quite horizontal, but rather higher at one end than the other. Thus the serum flows from the higher to the lower part; and, as it flows, some of the particles will be found to swim on their flat sides, and will appear to have a dark spot in the middle; while others will turn over from one side to the other as they roll down the glass. Many cruel experiments have been tried in order to observe the circulation of the blood in living creatures, and an apparatus has been invented for viewing the circulation in the mesentery of a frog; but as this can answer no useful purpose, and will never be put in practice by persons of humanity, we forbear to mention it.
Microscope II. Besides the objects for the microscope already mentioned, there are innumerable others, some hardly visible, and others totally invisible, to the naked eye; and which therefore, in a more peculiar sense, are denominated,
Microscopic animals. They are the animalcules or moving bodies in water, in which certain substances have been infused; and of which there are a great many different kinds. These animalcula are sometimes found in water which we would call pure, did not the microscopes discover its minute inhabitants; but not equally in all kinds of water, or even in all parts of the same kind of it. The surfaces of infusions are generally covered with a scum which is easily broken, but acquires thickness by standing. In this scum the greatest number of animalcules are usually found. Sometimes it is necessary to dilute the infusions; but this ought always to be done with water, not only distilled, but viewed through a microscope, lest it should also have animalcules in it, and thus prove a source of deception. It is, however, most proper to observe those minute objects after the water is a little evaporated; the attention being less diverted by a few objects than when they appear in great numbers. One or two of the animalcules may be separated from the rest by placing a small drop of water on the glass near that of the infusion; join them together by making a small connection between them with a pin; and as soon as you perceive that an animalcule has entered the clear drop, cut off the connection again.
Ceils in paste are obtained by boiling a little flour and water into the consistence of book-binders paste; then exposing it to the air in an open vessel, and beating it frequently together to keep the surface from growing mouldy or hard. In a few days it will be found peopled with myriads of little animals visible to the naked eye, which are the ceils in question. They may be preserved for a whole year by keeping the paste moistened with water; and while this is done, the motion of the animals will keep the surface from growing mouldy. Mr Baker directs a drop or two of vinegar to be put into the paste now and then. When they are applied to the microscope, the paste must be diluted in a piece of water for them to swim in.
Numberless animalcules are observed by the microscope in infusions of pepper. To make an infusion for this purpose, bruise as much common black pepper as will cover the bottom of an open jar, and lay it thereon about half an inch thick: pour as much soft water into the vessel as will rise about an inch above the pepper. Shake the whole well together: after which they most not be stirred, but be left exposed to the air for a few days; in which time a thin pellicle will be formed on the surface, in which innumerable animals are to be observed by the microscope.
The microscopic animals are so different from those of the larger kinds, that scarce any sort of analogy seems to exist between them; and one would almost be tempted to think that they lived in consequence of laws directly opposite to those which preserve ourselves and other visible animals in existence. They have been systematically arranged by O. F. Muller; though it is by no means probable that all the different classes
have yet been discovered. Such as have been observed, however, are by this author divided in the following manner.
This is by our author defined to be "an invisible (to the naked eye), pellucid, simple, punctiform worm;" but of which, small as it is, there are several species.
1. The monas termo or gelatinosa, is a small jelly-like point, which can be but imperfectly seen by the single microscope, and not at all by the compound one. In a full light they totally disappear, by reason of their transparency. Some infusions are so full of them that scarce the least empty space can be perceived; the water itself appearing composed of innumerable globular points, in which a motion may be perceived somewhat similar to that which is observed when the sun's rays shine on the water; the whole multitude of animals appearing in commotion like a hive of bees. This animal is very common in ditch-water, and in almost all infusions either of animal or vegetable substances.
2. Monas atomus or albida; white monas with a variable point. This appears like a white point, which thro' a high magnifier appears somewhat egg-shaped. The smaller end is generally marked with a black point, the situation of which is variable; sometimes it appears on the large end, and sometimes there are two black spots in the middle. This species was found in sea-water, which had been kept through the whole winter, but was not very fetid. No other kind of animalcule was found in it.
3. Monas punctum or nigra, black monas. This was found in a fetid infusion of pears, and appears in form of a very minute, opaque, and black point, moving with a slow and wavering motion.
4. Monas ocellus, transparent like a tale, with a point in the middle. This is found in ditches covered with con-
serva,
Microscope serves, and sometimes with the cyclidium milium; the margin of it is black, with a black point in the middle.
5. Monas lens or hyalina; of a tallowy appearance. This is found in all kinds of water; sometimes even in that which is pure, but always in the summer-time in ditch-water. It is found also in all infusions of animal or vegetable substances, whether in fresh or salt water; myriads being contained in a single drop. It is found likewise in the filth of the teeth. It is nearly of a round figure; and so transparent, that it is impossible to discover the least vestige of intestines. They generally appear in clusters, but sometimes singly. Contrary to what happens to other animalcules, they appear to cover the edges of the drop when evaporating, and where they instantly die. A few dark shades, probably occasioned by the wrinkling of the body, are perceived when the water is nearly evaporated. The motions of this animalcule are generally very quick; and two united together, may sometimes be seen swimming among the rest; which is thought to be a single one generating another by division, as is related under the article ANIMALCULE. These and the animalcules of the first species are so numerous, that they exceed all calculation even in a very small space.
6. Monas mica, marked with a circle. This is found in the purest waters, and may be discovered with the third lens of the single microscope when the magnifying power is increased. It appears like a small lucid point; but can assume an oval or spherical shape at pleasure; sometimes the appearance of two kidneys may be perceived in its body, and there is commonly the figure of an ellipse in it; the situation of which is moveable, sometimes appearing in the middle and sometimes approaching to either extremity. It seems encompassed with a beautiful halo, which is thought to be occasioned by the vibration of fine invisible hairs. It has a variety of motions, and often turns round for a long time in the same place.
7. The tranquilla, or egg-shaped transparent monas with a black margin, is found in urine which has been kept for some time. Urine in this state acquires a scum in which the animalcules reside; but though kept for several months, no other species was found in it. A drop of urine is usually fatal to other animalcules, though this species is to be met with in no other substance. It is generally fixed to one point, but has a kind of vacillatory motion. Frequently these creatures are surrounded with a halo. Sometimes they are quadrangular, and at other times spherical; the black margin is not always to be found; and sometimes there is even an appearance of a tail.
8. The lamellula, or flat transparent monas, is most usually found in salt-water; is of a whitish colour and transparent, more than twice as long as it is broad, with a dark margin, having a vacillatory motion, and frequently appearing as double.
9. The pulvisculus or monas with a green margin. These are generally found in marshy grounds in the month of March. They appear like small spherical grains of a green colour on the circumference, having sometimes a green bent line passing through the middle. They appear sometimes in clusters, from three to seven or more in number, having a wavering kind of motion.
10. The mona, or transparent gregarious mona, is Microscope found in a variety of infusions, and is of that kind which multiplies by dividing itself. They appear in clusters of four, five, or sometimes many more; the corpuscles being of various sizes, according to the number collected into one group. The smaller particles, when separated from the larger, move about with incredible swiftness. A single corpuscle separated from the heap, and put by itself into a glass, soon increased in size till it nearly attained the bulk of the parent group. The surface then assumed a wrinkled appearance, and gradually became like the former, separating again into small particles, which likewise increased in bulk as before.
An invisible, very simple, pellucid worm, of a variable form.
1. The diffuens, branching itself out in a variety of directions. It is very rare, and only met with in fens; appearing like a grey mucous mass, filled with a number of black globules, and continually changing its figure, pushing out branches of different lengths and breadths. The internal globules divide immediately, and pass into the new formed parts; always following the various changes of the animalcule; which changes seem to proceed entirely from the internal mechanism of its body, without the aid of any external power.
2. The tenax, running out into a fine point. This is a pellucid gelatinous body, studded with black molecules, and likewise changing its figure, but in a more regular order than the former. It first extends itself in a straight line, the lower part terminating in a bright acute point. It appears to have no intestines; and when the globules are all collected in the upper part, it next draws the pointed end up toward the middle of the body, which assumes a round form. It goes through a number of different shapes, part of which are described under the article ANIMALCULE. It is found in some kinds of river-water, and appears confined almost entirely to one place, only bending sideways.
An invisible, very simple, pellucid, spherical worm.
1. The punctum; of a black colour, with a lucid point. This is a small globule, with one hemisphere opaque and black, the other having a crystalline appearance; and a vehement motion is observed in the black part. It moves as on an axis, frequently passing thro' the drop in this manner. Many are often seen joined together in their passage through the water; sometimes moving as in a little whirlpool, and then separating. They are found in great numbers on the surface of fetid sea-water.
2. The granulum is of a spherical figure and green colour, the circumference being bright and transparent. It is found in marshy places about the month of June, and moves but slowly. It seems to have a green opaque nucleus.
3. The globulus, with the hinder part somewhat obscure, sometimes verges a little towards the oval in its shape, having a slow fluttering kind of motion, but more.
Microscope more quick when disturbed. The intestines are but just visible. It is found in most vegetable infusions, and is ten times larger than the mona lens.
4. The pilula, small and round, with green intestines. This is found in water where the lemma minor grows, in the month of December, and has a kind of rotatory motion, sometimes slow and at others quick. The intestines are placed near the middle, apparently edged with yellow. There is a small incision on one of the edges of the sphere, which may possibly be the mouth of the creature. The whole animal appears encompassed with an halo.
5. The grandinella, with immovable intestines, is much smaller than the last, and marked with several circular lines. The intestines are immovable, and no motion is perceived among the interior molecules. Sometimes it moves about in a straight line, at others irregularly, and sometimes keeps in the same spot, with a tremulous motion.
6. The socialis, with crystalline molecules placed at equal distances from one another. This is found in water where the chara vulgaris has been kept; and has its molecules disposed in a sphere, filling up the whole body of the animalcule; but whether they be covered by a common membrane or united by a stalk (as in the vorticella socialis to be afterwards described) is not known. When very much magnified, some black points may be seen in the crystalline molecules. Its motion is sometimes rotatory and sometimes not.
7. The sphericula, with round molecules, appears to consist of pellucid homogeneous points of different sizes. It moves slowly from right to left and back again, about a quarter of a circle each time.
8. The lunula, with lunular molecules, is a small roundish transparent body, consisting of an innumerable multitude of homogeneous molecules of the shape of a crescent, without any common margin. It moves continually in a twofold manner, viz. of the molecules among one another, and the whole mass turning slowly round. It is found in marshy places in the beginning of spring.
9. The globator, or spherical membranaceous volvox, is found in great numbers in the infusions of hemp and tremella, and in stagnant waters in spring and summer; it was first observed and depicted by Leewenhoek, but the descriptions of it given by authors differ considerably from each other. The following is that of Mr Baker. "There is no appearance of either head, tail, or fins. It moves in every direction, backwards, forwards, up or down, rolling over and over like a bowl, spinning horizontally like a top, or gliding along smoothly without turning itself at all; sometimes its motions are very slow, at other times very swift; and when it pleases it can turn round as upon an axis very nimble, without moving out of its place. The body is transparent, except where the circular spots are placed, which are probably its young. The surface of the body in some is as if all dotted over with little points, and in others as if granulated like shagreen. In general it appears as if set round with short moveable hairs." Another author informs us, that "they are at first very small, but grow so large that they can be discerned with the naked eye: they are of a yellowish green colour, globular figure, and in
substance membranaceous and transparent; and in the Microscope midst of this substance several small globes may be perceived. Each of these are smaller animalcula, which have also the diaphanous membrane, and contain within themselves still smaller generations, which may be distinguished by means of very powerful glasses. The larger globules may be seen to escape from the parent, and then increase in size."
This little animal appears like a transparent globule of a greenish colour, the foetus being composed of smaller greenish globules. In proportion to its age it becomes whiter and brighter, and moves slowly round its axis; but to the microscope its surface appears as if granulated, the roundest molecules fixed in the centre being largest in those that are young. The exterior molecules may be wiped off, leaving the membrane naked. When the young ones are of a proper size, the membrane opens, and they pass through the fissure; after which the mother melts away. Sometimes they change their spherical figure, and become flat in several places. They contain from 8 to between 30 and 40 globules within the membrane.
10. The morum, with spherical green globules in the centre. This is found amongst the lemma in the months of October and December, and has a slow rotatory motion. The globules seldom move, though a slow quivering motion may sometimes be perceived among them in the centre.
11. The alva, composed of green globules not enclosed in any membrane, is found in the month of August in water where the lemma polyrrhiza grows. It consists of a congeries of greenish-coloured globules, apparently of an equal size, with a bright spot in the middle; the whole mass is sometimes of a spherical form, sometimes oval, without any common membrane: a kind of halo may be perceived round it, and the mass generally moves from right to left, but scarce any motion can be perceived among the globules themselves. These masses contain from four to fifty globules, of which a solitary one may sometimes be seen. Sometimes also two masses of globules have been perceived joined together.
12. The vegetans, terminating in a little bunch of globules. This is found in river-water in the month of November. It consists of a number of floccose opaque branches invisible to the naked eye; and at the apex of these is a small congeries of very minute oval pellucid corpules. Muller, who discovered this, supposed it at first to be a species of microscopic and river ferularia; but he afterwards found the bunches quitting the branches, and swimming about in the water with a proper spontaneous motion; many of the old branches being deserted, and the younger ones furnished with them.
A simple, invisible, cylindric worm.
1. The viridis, or green enchelis, has an obtuse tail, the forepart terminating in an acute truncated angle; the intestines are obscure and indistinct. It continually varies its motion, turning from right to left.
2. The punctifera, having the fore part obtuse, the hinder part pointed. It is opaque, and of a green colour, with a small pellucid spot in the fore part, in which two black points may be seen; and a kind of double
Microscope double band crosses the middle of the body. The hinder part is pellucid and pointed, with an incision, supposed to be the mouth, at the apex of the fore-part. It is found in marshes.
3. The deser, or gelatinous encelis, is found, though rarely, in an infusion of lemon, and moves very slowly. The body is round, of a very dark-green, the fore-part bluntly rounded off, and the hinder part somewhat tapering, but finished with a round end: near the extremities there is a degree of transparency.
4. The similis, with moveable intestines, is found in water that has been kept for several months: it is of an egg-shape, and generally moves very quick, either to the right or left. It is supposed to be furnished with hairs, because when moving quickly the margin appears striated. The body is opaque with a pellucid margin, and filled with moveable spherules.
5. The serotina, with immovable intestines, is of an oval figure, partly cylindrical, the fore-part smaller than the hind, with a black margin, full of gray vesicular molecules: it moves very slowly.
6. The nebulosa, with visible moveable intestines, is found in the same water with the cyclidium glaucoma, but is much more scarce. The body is egg-shaped, the fore-part narrow, and frequently filled with opaque confused intestines: when moving, it elevates the fore-part of the body. It is about three times as large as the cyclidium glaucoma.
7. The feminulum is found in water that has been kept for some days, and moves by ascending and descending alternately. It is of a cylindrical figure, twice as long as broad, the intestines in the fore-part transparent, but opaque in the hinder part. Sometimes it is observed swimming about with the extremities joined together.
8. The intermedia, with a blackish margin, is one of the smallest animalcules: it has a transparent body, without any visible intestines. The fore and hind parts are of an equal size, and the edge is of a deeper colour than the rest. Some have a point in the middle, others a line passing through it.
9. The ovulum, is transparent, round, and egg-shaped. A very strong magnifier discovers some long foldings on the surface, with a few bright molecules here and there.
10. The pirum, with the hinder part transparent, has the fore-part protuberant and filled with molecules. The hinder part is smaller and empty, with moveable molecular intestines. Its motion is rapid, passing backwards and forwards through the diameter of the drop. When at rest, it appears to have a little swelling on the middle of the body.
11. The tremula was found in an infusion with the paramæcia aurelia, and many other animalcules. It is among the least of these minute creatures, and is of a cylindrical figure and gelatinous texture. Its extremity appears pointed, and has a tremulous motion, so as to induce a suspicion that the creature has a tail. Two of these creatures may at times be seen to adhere together.
12. The confrida, with a stricture in the middle, is found in salt-water, and is of a very small size, having the middle drawn in as if tied with a string. It is of an oval shape.
13. The elliptica, with a congeries of green intestines,
is found among the green matter on the sides of vessels Microscope in which water has been kept for some time. It is of a roundish shape, and transparent; the fore-part obtuse, the hinder part rather sharp, and marked with green spots. They are generated in such numbers, that myriads may sometimes be found in one drop.
14. The fusus, with both ends truncated, was found in water called pure, and had a languid motion. The body is round and transparent, with the fore and hind parts somewhat smaller than the rest. In the inside is a long and somewhat winding intestine, with a bright sky-coloured fluid, and some black molecules transversely situated.
15. The frutillus, with the fore-part truncated, is found in an infusion of grass and hay, and runs backward and forward through the drop with a wavering motion. It is one of the most transparent animalcules, and has the fore-part obtusely convex.
16. The caudata, with a kind of tail, is but seldom met with. The body is grey and transparent, with globular molecules divided from each other, and dispersed thro' the whole; the fore-part is thick and obtuse, the hind part crystalline and small, the end truncated.
17. The epiflomium, with the fore-part slender and roundish, is among the smaller animalcula; the body cylindrical and bright, the hind part obtuse, the fore-part smaller, and terminating in a globule, with now and then a black line down the middle.
18. The gemmata is found in ditch-water where the lemma thrives. It has a cylindrical body, the upper part running out into a transparent neck, with a double series of globules running down the body. It moves slowly, and generally in a straight line.
19. The retrograda moves commonly sideways, and sometimes in a retrograde manner. It has a gelatinous transparent body, thicker in the middle than at the ends, without any thing that can be called intestines, except a pellucid globule discoverable near the hinder part.
20. The festinans, with obtuse ends, is found in sea-water, and has a quick vacillatory motion from one side to the other. The body is round, with the fore-part transparent. More than half the length of it is without any visible intestines; but the lower end is filled with minute vesicular and transparent globules; a large globular vesicle is also observed in the fore-part.
21. The foremen was found by Joblot in an infusion of blue bottles, moving very slowly in an undulatory manner. The body is cylindrical, about four times as long as broad, truncated at both ends, the intestines opaque, and not to be distinguished from one another. It forms itself into the shape of the letter S, by turning the two extremities contrariwise.
22. The index is found in water with the lemma minor; the body opaque, of a grey colour, and long conical shape: the lower end is obtuse, one side projecting like a finger from the edge, with two very small projections from the lower end. It has the power of retracting these projections, and making both ends appear obtuse.
23. The truncus, with a kind of head, is the largest of this kind of animalcules. The body is grey, long, and mucous; the fore-part globular, the hinder part obtuse; but it can alter its shape considerably. Sometimes there is an appearance of three teeth proceeding from
Microscope from one of the sides. Globules of different sizes may be observed within the body. The creature rolls slowly about from right to left.
24. The larva is long, round, and filled with molecules. The fore-part is obtuse and transparent, with a kind of neck or small contraction formed near this end: the lower part is pointed; and about the middle of the body are two small pointed projections like nipples, one on each side.
25. The spatula, with the fore-part transparent, and of the shape of a spatula. It is perfectly cylindrical, crystalline, and marked with fine longitudinal furrows; having generally two transparent globules, one below the middle, the other near the extremity. It moves in a wavering kind of manner, retaining its general form, but moving the spatula in various ways. Muller informs us, that he saw it once draw the spatula within the body, and keep it there for two hours.
26. The pupula, with the fore-part papillary, is found in dung-hill water in November and December: it has a rotatory motion on a longitudinal axis, and moves in an oblique direction through the water. Both ends are obtuse; and the hinder part is marked with a transparent circle, or circular aperture.
27. The pupa, with a small nipple proceeding from the apex, has a very slow motion, and resembles the former, only that it wants the transparent circle, and is much larger. It is all opaque but the fore-end, and filled with obscure points.
A very simple, invisible, round, and rather long worm.
1. The lineola is found in most vegetable infusions in such numbers, that it seems to fill up almost the whole of their substance. It is so small, that with the best magnifiers we can discern little more than an obscure tremulous motion among them. It is more slender than the monas terma.
2. The rugula is like a bent line; and sometimes draws itself up in an undulated shape, at others moves without bending the body at all.
3. The bacillus, equally truncated at both ends, is found in an infusion of hay: but Muller mentions the following remarkable fact, viz. that having made two infusions of hay in the same water, he put the hay whole in the one, but cut it in pieces in the other: he found in the former none of the vibrio bacillus, but many of the monas lens and kolpoda cucullus; in the latter were many of the vibrio, but few of the other.—This is from six to ten times longer than the monas lens, but much more slender.
4. The undula, is a round, gelatinous, little, undulating line. This is the animal which Leewenhoeck says is less than the tail of one of the feminal animalcules. It never appears straight; but when at rest it resembles the letter V, and when in motion the letter M. It commonly rests on the top of the water: sometimes it fixes itself by one extremity, and whirls round.
5. The serpens, with obtuse windings or flexures, is found in river-water, but seldom. It is slender, and gelatinous, resembling a serpentine line, with an intestine down the middle.
6. The spirillum is exceedingly minute, and twisted in the form of a spiral, which seems to be its natural
No 219.
shape, as it never untwists itself, but moves forward in a straight line, vibrating the hind and fore parts. It was found in 1782 in an infusion of the sonchus arvensis.
7. The vermiculus has a milky appearance, with an obtuse apex, and a languid undulatory motion, like that of the common worm. It is found in marshy water in November, but seldom. It is thought to be the animal mentioned by Leewenhoeck as found in the dung of the frog and spawn of the male libellula.
8. The intestinum is found in marshy waters, and has a slow progressive motion. It is milk-coloured, with two obtuse ends, and four or five spherical eggs are perceivable at the hinder extremity.
9. The bipunctatus is found in fetid salt-water, and moves slowly; for the most part in a straight line. The body is pellucid, and of a tale-like appearance; both ends are truncated, and in the middle one or two pellucid globules placed lengthwise.
10. The tripunctatus is also transparent and tacy, with both ends tapering. It has three pellucid globules, the middle one of which is largest, the space between them being generally filled with a green matter. It moves in a straight line, backwards and forwards.
11. The paxilifer, or straw-like vibrio, consists of a transparent membrane, with yellow intestines, and two or three visible points. They are found in parcels together from seven to forty in number, and ranged in a variety of forms. When at rest, they generally assume a quadrangular figure; and are thought to have some affinity to the hair-like animal described by Mr Baker, and of which an account is given under the article ANIMALCULE, no 3.
12. The lunula, or bow-shaped vibrio, resembles the moon at its first quarter; it is of a green colour, and has from seven to ten globules disposed in a longitudinal direction.
13. The verminus is found in great plenty in salt-water kept for some days till it becomes fetid. It moves quickly, and with an undulatory motion, backwards and forwards. It is a long transparent membrane, with the hind part broader than the fore one. These animalcula seem to be joined together in a very singular manner.
14. The malleus is found in great plenty in spring-water, and is alternately at rest and in motion every moment; in the former case resembling the letter T, and in the latter V. It is a white pellucid animalcule, with a globule affixed to the base.
15. The acus is in the shape of a sewing needle; the neck round and partly transparent, and marked in the middle with a red point; the tail resembling a fine bristle.
16. The sagitta, with a setaceous tail, has a long and flexible body; broadest about the middle, and filled there also with grey molecules; the fore-part being drawn out into a thin and transparent neck, and the upper end thick and black. It is found in salt-water, and seems to move by contracting and extending its neck.
17. The gordius, with a tail terminated by a small tubercle, was found in an infusion made with salt water. Its fore part throughout about one sixth of its length is transparent, and furnished with an alimentary tube of a sky colour; the lower part being
Microscope ing bright and pointed, and the middle full of small globules.
18. The serpentulus, somewhat pointed at both ends. This is found in the infusions of vegetables which have been kept for some weeks. Its body is of a whitish colour, frequently convoluted, and drawn into different figures. The tail is furnished with a long row of very minute points.
19. The coluber is found in river-water; the tail is extremely small, and bent so as to form a considerable angle with the body; the mouth, œsophagus, the molecules in the intestines, and the twiflings of them, are easily discerned.
20. The anguillula is divided into four varieties: 1. The vinegar celi; 2. That in paste; 3. That of fresh water; and, 4. That of salt. The two first are treated of under the article ANIMALCULE; the third is exceedingly transparent, with a few transverse lines upon the body, but without any appearance of intestines. Sometimes it has a long row of little globules, and is frequently furnished with two small oval ones: the tail terminates in a point. It has been found in the sediment formed by vegetables on the sides of vessels in which water had been kept for a long time. The fourth variety appears, when pressed between two glass plates, to be little more than two crystalline skins with a kind of intestines of a clay colour. The younger ones are furnished with pellucid molecules.
21. The linter, or ventricose oval vibrio, with a short neck, is found among the lemna, but not very frequently. It is among the larger kinds of animalcules, egg-shaped, pellucid, inflated, and somewhat depressed at top; having a moveable crystalline neck, and the belly filled with pellucid molecules.
22. The utriculus resembles a bottle; the belly is full of molecular intestines, the neck bright and clear, the top truncated, and some have a pellucid point at the bottom of the belly. It has a constant and violent vacillatory motion, the neck moving very quickly from side to side.
23. The fasciola is found in water just freed from the frost, and not often in any other fluid. It is pellucid, with intestines like points in the middle. There is likewise an alimentary canal gradually diminishing in size. Its motion is very quick.
24. The colymbus is larger than many of the other species of vibrio, and resembles a bird in shape. The neck, which is a little bent, is round, shorter than the trunk, of an equal size throughout, and of a bright appearance, with the apex obtuse. The trunk is thick, somewhat triangular, full of yellow molecules; the fore-part broad, the hinder part acute, the motion slow.
25. The striatus has a linear body, being a bright membranaceous thread; the hinder part somewhat thicker, round, and filled with molecules, excepting at the end, where there is a small empty pellucid space. It can draw in the slender filiform part at pleasure.
26. The anas, with both ends attenuated, and the neck longer than the tail, is found in salt water; tho' a kind is likewise found in fresh water with a neck longer than the other. The trunk of this animalcule is oblong, opaque, and filled with molecules; the fore and hind parts are drawn out into a pellucid taly membrane, which the creature can retract at pleasure.
27. The cyanus is a very pellucid line, crooked at top, swelling in the middle, and sharp at the end; the middle full of dark coloured molecules and pellucid intestines. It is very small, and moves more slowly than any of those that move and advance their necks.
28. The anser is found in water where duckweed grows. The trunk is elliptic, round, and without any inequality on the sides. It is full of molecules: the hind part sharp and bright; the fore part produced into a bending neck, longer than the body; the apex whole and even, with blue canals passing between the marginal edges, occupying the whole length of the neck; and in one of them a violent descent of water to the beginning of the trunk is observable. It moves the body slow, but the neck more briskly.
29. The olor is found in water that has been kept for a long time, and is full of vegetable green matter. The body is elliptical and ventricose, the hind part somewhat sharp, and sometimes filled with darkish molecules. The neck is three or four times longer than the body; of an equal size throughout, and is moved very quickly; but the motion of the body itself is slow.
30. The fals, with a crooked neck, and obtuse hinder part, is pellucid and elliptical; the fore part lessening into a little, round, bright neck, nearly as long as the trunk. The latter is somewhat gibbous, and filled with very small molecules; and there are two small bright globules, one within the hind extremity, and the other in the middle of the body. The neck of this animalcule is immovable; whence it moves something like a scythe.
31. The intermedius appears to be an intermediate species betwixt the fax and the fasciola. It seems to be a thin membrane constantly folded. The whole has a crystalline taly appearance; the middle filled with grey particles of different sizes. It has all round a distinct bright margin.
A simple, invisible, flat, pellucid, orbicular or oval worm.
1. The bulla, or orbicular bright cyclidium. This is found occasionally in an infusion of hay. It is very pellucid and white, but the edges somewhat darker than the rest. It moves slowly, and in a semicircular direction.
2. The millium is very pellucid, and splendid like crystal; and of an elliptical figure, with a line through the whole length of it. The motion is swift, interrupted, and fluttering.
3. The fluitans is one of the smallest animalcula; the body somewhat of an oval shape, with two small blue spaces at the sides.
4. The glaucoma has an oval pellucid body, with both ends plain, or an oval membrane with a distinct well-defined edge. The intestines are so transparent, that they can scarcely be discerned when it is empty. When full, they are of a green colour, and there are dark globules discoverable in the middle. When there is plenty of water this animalcule moves swiftly in a circular and diagonal direction; when it moves slowly, it seems to be taking in water, and the intestines are in a violent commotion. It generates by division.
5. The nigricans is very small, pellucid, and flat, with a black margin.
6. The rostratum is oval, smooth, and very pellucid, with the fore part running out into an obtuse point, with which it seems to feel and examine the bodies to which it comes. The intestines are filled with a blue liquor, the colour of which sometimes vanishes, and then they seem to be composed of vesicles.
7. The nucleus resembles a grape seed, the body being pellucid and depressed, the fore part obtusely convex, and the hind part acute.
8. The hyalinum has a tremulous kind of motion; the body oval, flat, and bright, without any visible intestines.
9. The pediculus is scarce ever seen but on the hydra pallida, upon which it runs as if it had feet. It is gelatinous and white; the bottom gibbous over the back; the extremities depressed and truncated, with one end sometimes apparently cloven into two, which may be supposed the mouth.
10. The dubium is of an oval shape, with one side convex, the other concave; the margin pellucid, and the inner part containing a great number of molecules.
An invisible, membranaceous, flat, and pellucid worm.
1. The aurelia is membranaceous, pellucid, and four times longer than it is broad; the fore part obtuse and transparent; the hind part filled with molecules. It has somewhat the appearance of a gimlet by reason of a fold which goes from the middle to the apex, and is of a triangular figure. It moves in a rectilinear and vacillatory manner. It is found in ditches where there is plenty of duckweed, and will live many months in the same water without any renewal of the latter.
2. The chrysalis is found in salt water, and differs very little from the former, only the ends are more obtuse, and the margins are filled with black globules.
3. The versutum is found in ditches, and has an oblong, green, and gelatinous body, filled with molecules; the lower part thicker than the other; and both ends obtuse. It propagates by division.
4. The oviferum is membranaceous, oval, grey, and pellucid, with many oval corpulescles dispersed through the body.
5. The marginatum is flat, elliptical, and every where filled with molecules, except in the lower end where there is a pellucid vesicle. It is surrounded by a broad double margin, and a bright spiral intestine is observable.
An invisible, pellucid, flat, and crooked worm.
1. The lamella is very seldom met with. It resembles a long, narrow, and pellucid membrane, with the hind part obtuse, narrower, and curved towards the top. It has a vacillatory and very singular motion; going upon the sharp edge, not on the flat side as is usual with microscopic animals.
2. The gallinula is found in fetid salt water; and has the apex somewhat bent, the belly oval, convex, and striated.
3. The rostrum is found though seldom, in water
where the lemma grows; and has a slow and horizonal motion. The fore part is bent into a kind of hook; the hind part obtuse, and quite filled with black molecules.
4. The ochrea is depressed, membranaceous, and flexible; one edge nearly straight; the other somewhat bent, filled with obscure molecules, and a few little bladders dispersed here and there.
5. The mucronata is a dilated bright membrane; the apex an obtuse point, with a broad marked border running quite round it. It is filled with grey molecules within the margin, and has a truncated appearance.
6. The triquetra was found in salt water, and appears to consist of two membranes; the upper side flattened, the lower convex, with the apex bent into a kind of shoulder.
7. The friata is likewise found in salt water, and is very pellucid and white, with the upper part rather bent, and terminating in a point; the lower part obtusely round: there is a little black pellucid vesicle at the apex; and with a very great magnifying power the body appears covered with long streaks.
8. The nucleus is of an oval shape, with the vertex pointed, and of a brilliant transparency, by which the viscera are rendered visible. These consist of a number of round diaphanous vesicles.
9. The melagris has a dilated membrane, with very fine folds, which it varies in a moment. The fore part of the body to the middle is clear and bright; the hind part variously folded in transverse and elevated plaits and full of molecules. Beneath the apex are three or four teeth; but in some the edge is obtusely notched, and set with smaller notches. In the hinder part are 12 or more equal pellucid globules.
10. The affinis is found on the sea-coast, and has an elliptical mass in the middle, but is not folded like the former. The margin of the fore part is notched from the top to the middle; the lower part swells out, and contracts again into a small point.
11. The cucullus is found in vegetable infusions, and in fetid hay; moving in all directions, and commonly with great vivacity. It is very pellucid, and has a well defined margin, filled with little bright vesicles differing in size, and of no certain number. Its figure is commonly oval, with the top bent into a kind of beak, sometimes oblong, but most commonly obtuse. It has in the inside from 8 to 24 bright little vesicles not discernible in such as are young. Some have supposed these to be animalcules which this creature has swallowed; but Mr Muller is of opinion that they are its offspring. When this creature is near death by reason of the evaporation of the water, it protrudes its offspring with violence. From some circumstances it would seem probable that this animalcule casts its skin, as is the case with some insects.
12. The cucullulus is found in an infusion of the sonchus arvensis. It is very pellucid and crystalline, with several globules, and has an oblique incision a little below the apex.
13. The cuculus is elliptical, flat on the upper side, and convex on the under; the fore part is clear, and from the middle to the hinder part is full of silver-like globules. It frequently stretches out the fore part, and folds it in different positions.
Microscope 14. The ren, or crassa, is found in an infusion of hay, commonly about 13 hours after the infusion is made, and has a quick and vacillatory motion. Its body is yellow, thick, and somewhat opaque; curved a little in the middle, so that it resembles a kidney; and full of molecules. When the water in which it swims is about to fail, it takes an oval form, is compressed, and at last bursts.
15. The pirum has an uniform and transparent body, without any sensible inequality; and is of a pale colour, with obscure little globules. It propagates by division.
16. The cuneus is white, gelatinous, and without any distinct viscera; having a bright striated pellucid pulse on one side of the fore part. The apex has three or four teeth; and it can bend the hinder part into a spiral form.
An invisible, simple, smooth, and angular worm.
1. The pellorale is found in pure water, and moves alternately towards the right and left. It is quadrangular and pellucid, with 16 spherical molecules of a greenish colour, "set in a quadrangular membrane, like the jewels in the breast-plate of the high-priest, reflecting light on both sides."
2. The pulvinatum is found in dunghills; and appears like a little quadrangular membrane, plain on both sides: but with a large magnifier it appears like a bolster formed of three or four cylindric pillows sunk here and there.
3. The corrugatum is found in various kinds of infusions; and is somewhat of a square shape, very small, and in some positions appears as streaked.
4. The rectangulum differs but little from the former: the angle at the base is a right one; the larger vesicle is transparent, the rest green.
5. The truncatum is found chiefly in pure water, and then but seldom. It has a languid motion, and is much larger than the foregoing. The fore part is a straight line, with which the sides form obtuse angles, the ends of the sides being united by a curved line. The internal molecules are of a dark green, and there are two little bright vesicles in the middle.
A very simple, hollow, membranaceous worm.
1. The truncatella is visible to the naked eye; white, oval, and truncated at the top, where there is a large aperture descending towards the base. Most of them have four or five yellow eggs at the bottom. They move from left to right, and from right to left; ascending to the surface in a straight line, and sometimes rolling about while they descend.
2. The bullina is pellucid and crystalline, having splendid globules of different sizes swimming about with it. The under side is convex, the upper hollow, with the fore part forming a kind of lip.
3. The birundinella has two small projecting wings, which give it somewhat of the appearance of a bird; and it moves something like a swallow. It is invisible to the naked eye; but by the microscope appears a pellucid hollow membrane.
4. The duplex was found among duckweed, and appears like a crystalline membrane folded up, with-
out any visible intestines except a small congeries of Microscope points under one of the folds.
5. The globina has a roundish shape, and is hollow; the lower end being furnished with black molecules of different sizes, the fore part with obscure points, the rest entirely empty, and the middle quite transparent. It moves very slowly from right to left.
An invisible transparent worm with a tail.
1. The gyrinus greatly resembles the spermatic animals. It has a white gelatinous body; the fore part somewhat globular; the hind part round, long, and pointed. Sometimes it appears a little compressed on each side. When swimming it keeps its tail in continual vibration like a tadpole.
2. The gibba is found in the infusions of hay and other vegetables; and is small, opaque, gelatinous, white, and without any visible intestines.
3. The iniquita is found in salt water, and is remarkable for changing the shape of its body: sometimes it appears spherical, sometimes like a long cylinder, and sometimes oval. It is white and gelatinous, the tail filiform and flexible, the upper part vibrating violently. A pellucid globule may be observed at the base, and two very small black points near the top.
4. The lemna varies its form so much, that it might be mistaken for the proteus of Baker, described under the article ANIMALCULE; though in fact it is totally different. The body sometimes appears of an oblong, sometimes of a triangular, and sometimes of a kidney shape. The tail is generally short, thick, and annulated; but sometimes long, flexible, cylindric, and without rings; vibrating, when stretched out, with so much velocity, that it appears double. A small pellucid globule, which Muller supposes to be its mouth, is observable at the apex; and two black points not easily discovered, he thinks, are its eyes. Sometimes it draws the tail entirely into the body. It walks slowly after taking three or four steps, and extends the tail, erecting it perpendicularly, shaking and bending it; in which state it very much resembles a leaf of the lemna.
5. The turbo, with a tail like a bristle, is found among duckweed. It is of a tallowy appearance, partly oval and partly spherical; and seems to be composed of two globular bodies, the lowermost of which is the smallest, and it has two little black points like eyes on the upper part. The tail is sometimes straight, sometimes turned back on the body.
6. The poduria is found in November and December, in marshy places covered with lemna. It is pellucid; and seems to consist of a head, trunk, and tail: the head resembles that of a herring; the trunk is ventricose and full of intestines, of a spiral form and black colour. The tail most commonly appears to be divided into two bristles. The intestines are in a continual motion when the body moves, and by reason of their various shades make it appear very rough. There are likewise some hairs to be perceived. It turns round as upon an axis when it moves.
7. The viridis is found in the spring in ditches of standing water; and in some of its states has a considerable resemblance to the last, but has a much greater power of changing its shape. It is naturally cylindrical,
Microscope lindreal, the lower end sharp, and divided into two parts; but sometimes contracts the head and tail so as to assume a spherical figure.
8. The setifera is found in salt water, but seldom. It is small, the body rather opaque, and of a round figure. The upper part is bright, and smaller than the rest; the trunk is more opaque; the tail sharp, and near it a little row of short hairs. It has a slow rotatory motion.
9. The hirta was likewise found in salt water. It is opaque and cylindrical; and when in motion, the body appears to be surrounded with rows of small hairs separated from each other.
10. The crumena has a ventricose, cylindrical, thick, and wrinkled body; the lower part small; the upper part terminating in a small strait neck like that of a pitcher; the tail linear, and terminating in two diverging points.
11. The catellus has a moveable head fixed to the body by a point. The abdomen is twice as long as the head, full of intestines, and has a tail still narrower, and terminating in two bristles which it can unite and separate at pleasure. It moves briskly, but without going far from its first place.
12. The catelina was found in a ditch where there was plenty of duckweed. It is larger than the preceding, and has a thicker and more cylindrical body; the lower part truncated, with two short diverging points projecting from the middle.
13. The lupus is found in water among duckweed, and is larger than most of the genus. The head is larger than the body; the apex turned down into a little hook; the tail is like the body, but narrower, terminating in two very bright spines, which it extends in different directions. Sometimes it contracts into one half its common size, and again extends itself as before.
14. The vermicularis is long, cylindrical, fleshy, and capable of changing its shape. It is divided into eight or nine rings or folding plaits; the apex either obtuse, or notched into two points; the hinder part rather acute, and terminating in two pellucid thorns, between which a swelling is sometimes perceived. It often projects a kind of cloven proboscis from the incision at the apex. It is found in water where there is duckweed.
15. The foreipata is found in marshy places, is cylindrical and wrinkled, with a forked proboscis which it can thrust out or pull in.
16. The pleurometes is found in water which has been kept for several months. It is membranaceous, roundish, and white, with two blackish points in the fore part, the hinder part being furnished with a slender sharp tail. It has orbicular intestines of different sizes in the middle; the larger of them bright. The motion is vacillatory; and in swimming it keeps one edge of the lateral membrane upwards, the other folded down.
17. The tripos is flat, pellucid, triangular, having each angle of the base or fore part bent down into two linear arms, the apex of the triangle prolonged into tail. It is found in salt water.
18. The cyclidium is frequently found in pure water, and has an oval, smooth, membranaceous, pellu-
cid body with a black margin. The tail is concealed Microscope under the edge, and comes out from it at every motion, but in such a manner as to project but little from the edge. There is also a kind of border to the hinder part.
19. The tenax appears like an oval pellucid membrane, something larger than the monas lens. The fore edge is thick and truncated; the hinder part acute, and terminating in a short tail. It whirls about in various directions with great velocity.
20. The disco is a small orbicular animalcule, with a bent tail.
21. The orbis is round, and has a tail consisting of two long bristles.
22. The luna is likewise round, and has the fore-part hollowed into the form of a crescent.
An invisible, pellucid, and ciliated worm.
1. The conflictor, with moveable intestines, is perfectly spherical and semitransparent, of a yellow colour, the edges dark. It rolls from right to left, but seldom removes from the spot where it is first found. It is filled with a number of the most minute molecules, which move as if they were in a violent conflict; and in proportion to the number of these little combatants which are accumulated either on one side or other, the whole mass rolls either to the right or left. It then remains for a little time at rest, and the conflict ceases; but it soon becomes more violent, and the sphere moves the contrary way in a spiral line. When the water begins to fail, they assume an oblong, oval, or cylindric figure; the hinder part of some being compressed into a triangular shape, and the transparent part escaping as it were from the intestines, which continue to move with the same violence till the water fails, when the molecules float into a shapeless mass, which also soon vanishes, and the whole assumes the appearance of crystals of sal ammoniac.
2. The mamilla is of a dark colour, and filled with globular molecules; short hairs are curved inwards; and it occasionally projects and draws in a little white protuberance. It is pretty common in marshy water.
3. The wirescens is a large, pear-shaped, greenish-coloured animalcule, filled with opaque molecules, and covered with short hairs; generally moving in a straight line. It is found in salt water.
4. The viridis is much smaller than the former, and cannot lengthen or shorten itself as it does. Sometimes it appears contracted in the middle, as if it were to be divided in two.
5. The burfata is found in salt water, and is similar in many respects to the former. It is of a long oval shape, bulging in the middle, and filled with green molecules, every where ciliated except at the apex, which is truncated and shaped somewhat like a purse; the hairs are sometimes collected into little fascicles.
6. The postbuma is globular, and covered as it were with a pellucid net; is found in fetid salt water.
7. The aurea is yellow, oval; has both ends equally obtuse; little hairs discovered with difficulty; and has in general a vehement rotatory motion.
8. The pertusa is found in salt water; and is gelatinous
Microscope tinous and small, without any molecules. The fore-part is truncated, the hind-part brought nearly to a point, with a kind of oval hole on one side.
9. The fracta is long, with sinuated angles, white, gelatinous, and granulated, changing its form considerably.
10. The dilatata appears like a gelatinous membrane, with a few grey molecules in the fore-part, and a great number in the hinder part. It is sometimes dilated into a triangular form with sinuated sides; at other times the shape is more irregular and oblong.
11. The scintillans was found in December among the lesser lemna. It is of a green colour, oval, round, and opaque. It is supposed to be ciliated from its bright twinkling appearance, which probably arises from the motion it gives the water.
12. The vesiculifera is oval, very pellucid, with a defined dark edge and inside, containing some very bright bladders or vesicles. The middle frequently appears blue, and the vesicles appear as if set in a ground of that colour.
13. The globulifera was found in a ditch where the lemna minor grew. The body is round, very pellucid, without molecules, but with three little pellucid globules, and every where set with short hairs.
14. The pustulata is found in marshy waters; and is white, gelatinous, and somewhat granulated; the lower part truncated as if an oblique section were made in an egg near the bottom. It is covered with little erect shining hairs, and at the lower extremity a few bright pustules may be discovered.
15. The turbinata is found in stinking salt water; and is round, pellucid, somewhat of the shape of an acorn, with a pellucid globule at the lower end.
16. The acuta is found in salt water, and is gelatinous, thick, capable of assuming different shapes; having the apex bright, and the rest of the body filled with little spherules. Sometimes it draws itself up into an orbicular shape, at others one edge is sinuated.
17. The notata is oval, round, and has a black point at the edge.
18. The candida is found in salt water; and is membranaceous, flat, very white, with no visible intestines except two oval bodies not easily perceived. The whole edge is ciliated.
19. The nodulata is oblong and oval, with a double row of little nodules.
20. The signata is common in salt water in the months of November and December. It is oblong and subdepressed, with a black margin filled with little molecules, but more particularly distinguished by a curved line in the middle somewhat in the shape of the letter S; one end of which is sometimes bent into the form of a small spiral.
21. The trigona is found in marshes, but not commonly. It is a yellow triangular mass filled with unequal pellucid vesicles, one of which is much larger than the rest, and the edge surrounded with short fluctuating hairs.
22. The fluida is somewhat of a kidney shape, but ventricose.
23. The flava is reniform and sinuated.
24. The annulata is round and annular.
25. The cornuta is of the shape of an inverted cone, opaque, and of a green colour. This requires to be
observed for some time before we can ascertain its characters. The body is composed of molecular vesicles; the fore part is wide and truncated, with a little prominent horn or hook on both sides; the hind part being conical, every where ciliated, and the hairs exceedingly minute; those in the fore part are three times longer than the former, and move in a circular direction. The hinder part is pellucid, and sometimes terminates in two or three obtuse pellucid projections. At one time this animalcule will appear reniform and ciliated on the fore part; but at another time the hairs are concealed. It dissolves into molecular vesicles when the water evaporates.
26. The heteroclitata appears to the naked eye like a white point; in the microscope as a cylindrical body, the fore part obtusely round, the middle rather drawn in; the lower part round, but much smaller than the upper part. It appears wholly ciliated through a large magnifier.
An invisible, pellucid, hairy worm.
1. The grandinella is a very small pellucid globule, with the intestines scarce visible, the top of the surface furnished with several small bristles not easily discoverable, as the creature has a power of extending or drawing them back in an instant. It is found in pure water as well as in infusions of vegetables.
2. The cometa is a pellucid globule filled with bright intestines, the fore part furnished with hairs, the hind part with a pellucid globule.
3. The granata resembles the two former; and has a darkish nucleus in the centre, with short hairs on the edge.
4. The trochus is somewhat of a pear-shape, and pellucid; each side of the fore part being distinguished by a little bunch of hairs.
5. The gyrinus is one of the smallest of this genus, and is found in salt water. It is smooth and free from hairs, except at the fore part, where there are a few.
6. The sol is small, globular, and crystalline; beset every where with diverging rays longer than the diameter of the body; the inside full of molecules. The body contracts and dilates, but the creature remains confined to the same spot. It was found with other animalcules in water which had been kept three weeks.
7. The solaris is orbicular, bright, and filled with globular intestines, frequently having in it a moveable substance of the shape of the letter S. It has hairs seldom exceeding 17 in number, set round the circumference, each of them nearly equal in length to the diameter of the animalcule.
8. The bomba is of a yellow colour, and full of clay-like molecules. It moves with such velocity as to elude the sight, and appears of various shapes, sometimes spherical, sometimes kidney-shaped, &c.
9. The orbis is composed of vesicular molecules; is of a spherical figure, smooth, pellucid, and a little notched in the fore part. The notched part is filled with long hairs, but there are none on the rest of the body.
10. The urnula is membranaceous, pellucid, somewhat in the form of a water pitcher, with the fore part hairy. It moves but slowly.
11. The diota is of a clay-colour, and filled with molecules;
Microscope molecules; the upper part cylindrical and truncated, the lower part spherical, the upper part of the mouth hairy at the edges.
12. The horrida is somewhat of a conical shape, the fore part rather broad and truncated, the lower part obtuse, and the whole covered with radiating bristles.
13. The urinarium is egg-shaped, with a short hairy beak.
14. The semiluna is smooth, pellucid, and shaped like a crescent.
15. The trigona is of a triangular shape, a little convex on both sides, the fore part acute and ciliated, the hind part broader, and having the extremity as it were gnawed off.
16. The stoma is round, not very pellucid, narrow in the fore part, and resembling an inverted club.
17. The nigra was found in salt water, and has an opaque body; but when at rest one side appears pellucid. When in violent motion, it seems entirely black.
18. The pubes is found in water where duckweed grows, chiefly in the month of December. It has a bunch above the hind part marked with black spots, depressed towards the top, a little folded, and somewhat convex on the under part. The apex is furnished with hairs, but they are seldom visible till the creature is in the agonies of death, when it extends and moves them vehemently, and attempting as it were to draw in the very last drop of water.
19. The floccus is membranaceous, the fore part rather conical, with three small hairy papillae projecting from the base.
20. The sinuata is found in river water. It is oblong and depressed, with one margin hollow and hairy, and the lower end obtuse. It is of a yellow colour, and the hollow edge ciliated.
21. The praecepta is pellucid, the fore part formed into a kind of neck; one edge rising into a protuberance like a hump-back, the other edge convex.
22. The proteus is that which Mr Baker distinguishes by the same name, and of which an account is given under the article ANIMALCULE. It is found in the slimy matter adhering to the sides of vessels in which vegetables have been infused, or animal substances preserved. That described by Mr Adams was discovered in the slime produced from the water where small fishes, water-snails, &c. had been kept. The body resembled that of a snail, the shape being somewhat elliptical, but pointed at one end, while from the other proceeded a long, slender, and finely proportioned neck, of a size suitable to the rest of the animal.
23. The versatilis lives in the sea, and has some resemblance to the proteus; but the neck is shorter, the apex less spherical, and the hinder part of the trunk acute.
24. The gibba is pellucid; the upper part swelled out, with numerous molecules, and three large globules on the inside. The ends rather incline downwards; and when the water begins to fail, a few minute hairs may be discovered about the head and at the abdomen; the body then becomes striated longitudinally.
25. The foeta somewhat resembles a rolling-pin in shape; has both ends obtuse, and one shorter than the other. It can draw in the ends, and swell out the sides, so as to appear almost spherical.
26. The patens is found in salt water; and is of a long cylindrical shape, filled with molecules, the fore part bright and clear, with a long opening near the top which tapers to a point, and is beset with hairs.
27. The patula is ventricose, rather inclining to an oval figure, with a small tube at the fore part, the upper part of which is hairy.
28. The foveata is oblong and rather broad, with three little horns on the fore part.
29. The striata is found in the month of December in river-water. It is a beautiful animalcule, of a fox colour. It is of an oblong shape, the lower end somewhat larger than the other. It has a set of streaks running from one end to the other, and at the abdomen a double row of little eggs lying in a transverse direction.
30. The uvula is found in the infusion of hay and other vegetables. It is six times longer than broad, round, flexuous, of an equal size, the greater part filled with obscure molecules; the fore part rather empty, with an alimentary canal and lucid globules near the middle. The margin of the fore part is covered with short hairs.
31. The aurantia is of a gold colour, pellucid, and filled with vesicles.
32. The ignita is of a fine purple colour, with something of a reddish cast, pellucid, splendid, with a number of globules of different sizes; the fore part small, the hinder part obtuse, with a very large opening which seems to run through the body.
33. The prisma is very small, and so transparent that it cannot easily be delineated. It is of a singular shape; the under part being convex, the upper compressed into a kind of keel, and the fore part small.
34. The foreps is found about the winter solstice in water covered with lemnas. It is of a yellow colour, large, somewhat transparent, and filled with molecules, with a large opaque globule in the lower part. The fore part is divided into long lobes, one of which is falciform and acute, the other dilated and obliquely truncated. It can open, shut, or cross, those lobes at pleasure; and by the motion of them it appears to suck in the water.
35. The forfex is found in river water. It has the fore part formed into a kind of forceps, one of which is twice as long as the other, hooked and ciliated.
36. The index is found in salt water, and has the under part of the front of the margin hairy; the apex is formed by the fore part projecting like a finger on a direction post.
37. The trichoda is of a yellow colour, formed of two pellucid membranes striated longitudinally; the lower end obliquely truncated, and the two extremities bent in opposite directions.
38. The navicula has three corners; the fore part truncated and ciliated, the hind part acute and bent a little upwards. It has a crystalline appearance, and a kind of longitudinal keel runs down the middle.
39. The sucessa is of a flattened oval shape, the edge hairy, and hollowed out in such a manner as to form two unequal legs.
40. The sulcata is ovate and ventricose, the apex acute, with a furrow at the abdomen, and both sides of it ciliated.
41. The anus is found in pure water; and is smooth, five
Microscope five times broader than it is long, filled with darkish molecules. It has a bright neck, under the top of which are a few unequal hairs. It moves but languidly.
42. The barbata is round, somewhat linear, with both ends obtuse; the fore part narrower, forming as it were a kind of neck, under which is a row of fluctuating hairs. The trunk is full of grey molecules.
43. The fascimen is long, round, pellucid, and covered with very minute hairs, and has a great number of mucous vesicles about the body.
44. The crisita is long, round, every where ciliated on the upper part, and the under part likewise hairy as far as the middle.
45. The angulus is long, more convex than most of the genus, divided by a kind of articulation in the middle into two parts equal in breadth, but of different lengths; the apex has short waving hair.
46. The linter is found in an infusion of old grass. It is egg-shaped, oblong, with both extremities raised so that the bottom becomes convex, and the upper part depressed like a boat: it is of different shapes at different ages, and sometimes has a rotatory motion.
47. The panillus is found in salt water; and is long, full of grey molecules; the fore part truncated and hairy, and rather smaller than the other.
48. The vermicularis is found in river water; and is pellucid in the fore part, with the hind part full of molecules.
49. The melitae is found in salt water, but very rarely. It is oblong, ciliated, with a globular apex, a dilatate neck, and a kind of peristaltic motion perceivable within it.
50. The fimbriata is subovate, the apex hairy, the hinder part obliquely truncated and serrated.
51. The camelus is found but rarely in vegetable infusions, and moves in a languid manner. The fore part is ventricose; the back divided by an incision in the middle into two tubercles; the lower part of the belly sinuated.
52. The augur is oblong, depressed, pellucid, and filled with molecules: the vertex is truncated, the fore part forming a small beak with three feet underneath; beyond which, toward the hinder part, it is furnished with bristles.
53. The pupa is roundish, pellucid, and consists of three parts. The head is broad, and appears to be hooded, the top being furnished with very small hairs; on the lower part of the head is a transparent vesicle, and over the breast from the base of the head hangs a production resembling the sheath of the feet in the pupa of the gnat.
54. The lunaris is round and crystalline; the hinder part smaller than the other. The edge of the back and the part near the tail are bright and clear. It bends itself into the form of an arch.
55. The bilunis is arched and flattened with an hairy apex, and two little bristles proceeding from the tail.
56. The rattus is oblong, with a kind of keel; the fore part hairy, and a very long bristle proceeding from the hinder part.
57. The tigris resembles the former, but differs in the form of the tail, which consists of two bristles, and likewise in having a kind of incision in the body a little below the apex.
58. The perillum is frequently found in marshes. It is cylindrical, pellucid, muscular, and capable of being folded up. It appears double; the interior part full of molecules, with an orbicular muscular appendage, which it can open and shut, and which forms the mouth. The external part is membranaceous, pellucid, dilated, and marked with transverse streaks; and it can protrude or draw in the orbicular membrane at pleasure. Some have four articulations in the tail, others five; and it has two pairs of bristles, one placed at the second joint, the other at the last.
59. The clavus has a considerable resemblance to a common nail; the fore part is round and hairy, the hinder part terminating in a sharp tail.
60. The cornuta is membranaceous, elliptical, full of molecules; the fore part lunated, the other round, and terminating in a tail as long as the body.
61. The gallina is found in river water. It is of a grey colour, flat, with seven large molecules and globules within it; the front obtuse, set with hairs; the hinder part terminating in a tail formed of very fine hairs.
62. The musculus is found in the infusions of hay which have been kept for some months. It is smooth, egg-shaped, with a double margin drawn underneath it; the fore part narrow, and furnished with short hairs which continually play about; having a small tail underneath. It moves slowly, and is furnished with molecular intestines.
63. The delphis is found in river water. It is smooth, pellucid, having the fore part dilated into a femicircle, gradually decreasing in breadth towards the tail. The front is hairy, the hairs standing as rays from the femicircular edge: one of the edges is sometimes contracted.
64. The delphinus is found in hay that has been infused for some months. It is pellucid, smooth, and egg-shaped; the hinder part terminating in a tail about half the length of the body, dilated at the upper end, truncated, and always bent upwards. It moves sometimes on its belly and sometimes on its side.
65. The clawa, or club trichoda, has the fore part thick, but the hinder part narrow; both extremities obtuse, pellucid, and replete with molecules; the hind part bent down towards the middle.
66. The cuniculus is oblong, the fore part hairy, the hinder part rather acute, and filled with molecules and black vesicles.
67. The filis is large and curved, the fore part small, the hinder part gradually diminishing into a tail, the under part beset with hairs longitudinally.
68. The piscis is oblong, the fore part hairy, the hind part terminating in a very slender tail. It is smooth, pellucid, much longer than broad, and filled with yellow molecules; the fore part obtuse, the hinder part extremely slender and transparent; the upper side convex.
69. The larus is long, round, beset with hairs, and has the tail divided into two points.
70. The longicauda is cylindrical; the fore part truncated, and beset with hairs; the tail long, furnished with two bristles, and having two joints.
71. The fixa has the circumference set with hairs, and a little solitary pedicle projecting from the body.
72. The inquilinus is sheathed within a cylindrical transparent
Microscope transparent bag, having a little pedicle bent back within the bag.
73. The ingenita is sheathed in a depressed bag, broadest at the base. The animalcule itself is funnel-shaped, with one or more hairs proceeding from each side of the mouth of the funnel. It can extend or contract itself within the bag, fixing its tail to the base, without touching the sides. It is found in salt water.
74. The innata is sheathed in a cylindrical bag, with a pedicle passing through and projecting beyond it.
75. The transfuga is broad, the fore part hairy, the hinder part full of bristles; one side sinuated, and the other pointed.
76. The ciliata is ventricose, the hinder part covered with hair.
77. The bulla is membranaceous, the sides bent inwards; the fore and hind parts both covered with hairs.
78. The pellionella is somewhat thick in the middle, and pellucid, with a few molecules here and there; the sides obtuse, the fore part ciliated with very fine hairs, the hinder part set with bristles.
79. The cylindium has the hinder extremity filled with globules of various sizes. It vacillates upon the edge, commonly advancing on its flat side, and continually drawing in water. It then gapes, and opens into a very acute angle, almost to the middle of the body; but this is done so instantaneously, that it can scarcely be perceived.
80. The cursor is oval, the fore part hairy, and the hinder part also furnished with some straight and curved hairs in two fascicles. Its body is flat, and filled with molecules; and in the fore part is an oblong empty space, into which we may sometimes see the water sucked in.
81. The pulex is egg-shaped, with an incision in the fore part; the front and base hairy.
82. The lynceus is nearly square, with a crooked beak and hairy mouth. It is membranaceous, and appears compressed, stretched out into a beak above, under which there is a little bundle of hairs; the lower edge bends in and out, and is surrounded with a few bristles. The intestines are beautiful, and a small bent tube goes from the mouth to them in the middle of the body. There is likewise another tube between the fore and hind edge, filled with blue liquor. The intestines and other tube are frequently in motion.
83. The erosa is orbicular, the fore part notched; one side furnished with hairs, the hinder part with bristles.
84. The rostrata is found in water where duckweed has been kept. It is depressed, capable of changing its shape, yellow, with long ciliated hairs; it has four feet tapering to a point, one of them longer than the rest. Both feet and hairs are within the margin. The shape of the body is generally triangular; the apex formed into an obtuse beak, which the creature sometimes draws in so that it appears quite round.
85. The logena is round, ventricose, with a long neck, and the lower end set with bristles.
86. The charon was found in salt water. It is oval, and resembles a boat as well in its motion as shape: the upper part is hollowed, the under part furrowed
No 219.
and convex; the stern round, with several hairs proceeding from it. Microscope
87. The cimex is about the size of the lynceus, has an oval body, with a convex back, flat belly, and incision in the margin of the fore part, the edges of which incision appear to move. When this animalcule meets with any obstacles in swimming, it makes use of four bristles, which appear on the under side as feet.
88. The cicada differs but little from the cimex. It is oval, with an obscure margin, the fore part covered with hairs on the under side, and the hinder parts beardless.
An invisible worm with horns.
1. The rastellum is found in river water. It has three rows of horns on the back, which occupy almost the whole of it.
2. The lynceaster is square, and its disc furnished with shining horns.
3. The bifris appears an oblong membrane, pellucid, with four or five black points in the fore part, which are continually changing their situation, thick set with small globules in the middle, among which four larger ones are sometimes perceived, which by Mr Adams are supposed to be eggs. In the middle of the hind part are some longitudinal strokes resembling bristles, which, however, do not seem to project beyond the body.
4. The cypsis is found in water covered with lemnas. It is somewhat of a pear shape, compressed, with a broad and blunt fore part; the front furnished with hairs or little vibrating points inserted under the edge, shorter in the hind part, partly extended straight, and partly bent down, having a retrograde motion.
5. The haustrum is orbicular, with the horns in the middle, the fore part membranaceous and ciliated, with several bristles at the hinder part.
6. The haustratum differs from the preceding only in having the hinder part without any bristles.
7. The patella has an univalved shell, is orbicular, crystalline; the fore part somewhat notched; the fleshy body in the middle of the shell; with horns or hairs of different lengths jutting out beyond the shell, and acting instead of feet and oars, some of which are bent; and the superior ones constitute a double transverse row.
8. The vannus is oval and rather flat, with one edge bent, the opposite one ciliated, the front furnished with horns, and the hind part with bristles.
9. The pullaster agrees in many respects with the trichoda pulex; the upper part is pellucid, without any black molecules; the front truncated, the whole surface of the head covered with hair, and the fore part sinuous.
10. The mytilus is a large animalcule; the fore and hind parts rounded, very pellucid and white, dark in the middle, with black intestines intermixed with a few pellucid vesicles; both extremities appearing as if composed of two thin plates. It has two small horns, with which it agitates the water so as to form a little whirlpool.
11. The lepus is egg-shaped, compressed, pellucid, and
Mic. scope and crowned with short waving hairs; the base terminated with bristles.
12. The filurus is an oval, smooth, animalcule, somewhat crooked and opaque, with a fascicle of vibrating hair on the fore part; it has a sharp tail furnished with unequal rows of moveable hairs, the back being also ciliated: the hairs produce a rotatory motion. The figure varies from oval to oblong, and the filaments of the conserva are often entangled in the tail.
13. The calvittum is found in the infusion of vegetables. The body is broad and flat, both sides obtuse, filled with black molecules, and there is a black spot near the hinder part, where there are likewise a few short bristles.
14. The pustulata is found in salt water. It is oval, convex; one edge of the hinder part sinuated, both ends set with hairs, and some horns on the fore part.
A pellucid, invisible, and ciliated worm.
1. The acarus is lively, conical, ventricose, full of black molecules, with a bright and transparent fore part. The lower part of the apex has rows of long hairs on the under part set like rays. Four locks of long crooked hair or feet proceed from the belly, and it is continually moving these and other hairs in various directions.
2. The ludio is a lively diverting animalcule, smooth, pellucid, full of small points, the fore part clubbed and a little bent, the hinder part narrow; the base obliquely truncated, and terminating in a tail stretched out transversely. The top of the head and middle of the back are furnished with long and vibrating hairs; three moveable and flexible curls hang down from the side of the head at a distance from each other. When the creature is at rest, its tail is curled; but when in motion, it is drawn tight and extended upwards.
5. The saunio is found, though seldom, in water where the lemma grows. The cilia are longer than the hairs, and are continually vibrating: it has two moveable curls hanging on the side of the head.
4. The volutator is shaped like a crescent, and has some crystalline points; the convex part has a row of hairs longest towards the tail, and underneath are four feet. It is very lively, and often turns round with a swift circular motion.
5. The larva is long and ciliated in the middle; the body is depressed and long; the hinder parts acute, and generally curved, pellucid, and filled with granular molecules.
6. The charon is found in sea-water, but rarely. It is oval, pellucid, and membranous, with longitudinal furrows, and several bent diverging rows of hair below the middle, but none on the hinder part.
7. The corona is a membranous lamina, very thin, pellucid, crystalline, and semilunar: the edge of the base thick set with molecular intestines; the fore part furnished with a kind of mane; towards the hind part are three equal curved hairs or spines.
A naked worm with rotatory cilia, capable of contracting and extending itself.
1. The viridis is visible to the naked eye, appearing
like a small green point; but the microscope discovers Microscope it to be nearly cylindrical, a little thicker at the fore part than the other, and obtuse at both ends. It appears to be totally destitute of limbs, notwithstanding which it keeps the water in continual motion; so that it probably has some invisible rotatory instrument. It moves sometimes circularly, sometimes in a straight line.
2. The spheroida appears also like a point; but thro' the microscope as a globular mass of a dark green colour. It occasions a vehement motion in the water, probably by means of some short hairs with which it is furnished.
3. The cinda is of an irregular shape, sometimes assuming an oval figure, and appearing as if girt round with a transverse keel. It is invisible to the naked eye, ciliated on every side; the hairs all moveable, and longer on one side than the other.
4. The lunifera is found in salt water; has the fore-part obtuse, the base broad, and hollowed away like a crescent, with a short protuberance in the middle of the concave part: the fore part is ciliated.
5. The burstata is found in salt water, and is ventricose, crammed with molecules; the fore part truncated, and both sides of it pellucid: there is a prominent papilla in the middle, which when the animalcule is at rest appears notched, the edge of the aperture being ciliated; the hairs are capable of moving in various directions.
6. The varia is cylindrical, truncated, opaque, and blackish-coloured; the fore part ciliated.
7. The sputarium is found in October, with the lesser lemma, and is one of the most singular of the microscopic animalcules. When viewed sideways, it is sometimes nearly cylindrical, only tapering a little towards the hinder part, and having a broad pellucid edge. Viewed from the top, it has sometimes a broad face or disc, furnished with radiating hairs, the under part contracted into a globular shape, of a dark green colour, and filled with small grains.
8. The polymorpha is visible to the naked eye, and appears like a green point moving with great agility; but when viewed through a microscope, it assumes such a variety of forms, that it is impossible to describe them. The body is granulous; and a series of pellucid points is sometimes to be observed.
9. The multiformis is found in salt water, and very much resembles the former.
10. The nigra is found in August in meadows covered with water. It may be seen with the naked eye, appearing like a black point swimming on the surface. Through the microscope it appears as a small conical body, obtuse and ventricose at one end and acute at the other. When the extremities are extended, two small white hooks become visible, by the assistance of which it moves in the water, and it probably has a rotatory organ: it moves continually in a vacillating manner on the top of the water.
11. The eucallus is likewise visible to the naked eye: it is of a dirty red colour, of a shape somewhat conical, and resembling a grenadier's cap.
12. The utriculata is green and ventricose; the belly capable of being lengthened or shortened; the fore part truncated, much in the shape of a common water
Microscope bottle; the neck is sometimes very long, sometimes very short, and filled with green molecules.
13. The occreata is met with in rivers, though very seldom, and in shape somewhat resembles the lower part of a boot. The apex of the upper part is truncated and ciliated, the heel pointed, and the foot round.
14. The walga is as broad as long, and the apex truncated and ciliated; both angles of the base projecting outwards, one somewhat like a wart, the other like a finger: It is found in marshy waters.
15. The papillaris is likewise found in marshes where the conerva nitida grows. It is ventricose; the fore part truncated, with a papillary tail, and a beautiful papillary excrecence on the side.
16. The fasciculatus is thick, of an equal diameter every where, and full of molecules. The edge of the mouth is bent back; the hinder part is obtuse, sometimes notched and contracted, with cilia to be seen on both sides of the mouth.
17. The cirrata is found in ditch-water. It is ventricose, the aperture sinuated, and two tufts of hair on each side of the belly.
18. The nasuta is invisible to the naked eye, but the microscope discovers it to be furnished with a rotatory organ encompassing the middle. It is pellucid, cylindrical, of an unequal size; the fore part truncated and ciliated, with a triangular prominence in the middle of the aperture; the hinder part is obtuse, with a point on each side of the middle of the body. When the water is nearly exhaled, two rotatory organs are observable; one on the fore part, and the other encompassing the middle of the body; the hairs of the latter being in violent motion. Other fascicles of moving hair are likewise to be observed; and the quick and various motions of this apparatus are very surprising.
19. The stellina is of an orbicular shape, with a molecular disc and ciliated margin.
20. The disceina is likewise orbicular, the edge ciliated, with a kind of handle on the under side.
21. The scyphina is bowl-shaped, crystalline, with an opaque spherule in the middle.
22. The albina is cylindrical in the fore part, the hinder part tapering, and almost ending in a point.
23. The frustillina is empty and cylindrical, with a truncated apex.
24. The truncatella is of the larger kind of animalcules, with a crystalline body, full of black molecules, the skin perfectly smooth and colourless, the hinder extremity rounded, and the anterior part truncated: at this extremity there is a large opening that serves for a mouth, which is thickly ciliated.
25. The limacina is cylindrical, truncated, and has two pairs of cilia.
26. The fraxinina is mostly cylindrical, the hinder part rather tapering, and full of opaque molecules; transparent towards the upper end. Within the edge at the top are two small tubercles, from each side of which proceeds a pair of small hairs.
27. The cratagaria is found in the month of April, both in the mud and on the tail of the monoculus quadricornis. They are generally heaped together in a spherical form, and united to one common stalk. They are likewise often to be found without a pedicle, the body rather contracted, the aperture circular, and sur-
rounded with a marked margin. It has two small Microscope arms; and with a powerful magnifier a violent rotatory motion may be observed. Sometimes an individual will separate from the community, and move in a kind of spiral line for a little time, and then go back to the rest.
28. The hamata is not ciliated, nor has it any hairs upon it; the body is granulated, the fore part broad and truncated, the hinder part obtuse, and capable of being contracted or extended.
29. The crateriformis is a lively animalcule, pellucid, round, longer than it is broad, approaching somewhat to a square figure, with convex sides: the head is situated at the large end, the skin smooth, and some traces of intestines may be discovered with difficulty. There is a considerable opening surrounded by hair at the larger end, and the filaments composing it are in continual motion. Two of them are sometimes seen joined together, and full of small sphericles. In this state they draw each other alternately different ways; the surface is smooth, and the hairs invisible.
30. The canaliculata appears to the naked eye as a number of white points adhering to the sides of the glass. When magnified, the fore part is narrower than the hind one; in the side is a kind of incision, and the hinder part is notched towards the middle. It excites a continual whirling motion in the water by means of a rotatory organ with which it is furnished.
31. The vesiculata is a pellucid, gelatinous animalcule, of a greenish colour, and furnished with small radii about the circumference; so that it appears like a very small water hedge-hog.
32. The ampulla is contained in a transparent bottle-shaped bag; the head divided into two lobes. It sometimes lies at the bottom of the bag, and sometimes nearly fills the whole of it.
33. The folliculata is gelatinous and cylindrical; and when most extended, the base appears attenuated, and the apex truncated.
34. The larva is of a clay colour, the aperture ciliated, with a globular projection at times appearing to proceed from it.
35. The facculata has the shape of an inverted cone, with an aperture in the figure of a crescent; the lower part of the trunk notched, forming as it were two teeth; the tail biphyllos. Each of these is surrounded with a loose bright skin, the head being divided from the trunk by a deep incision.
36. The aurita is cylindrical and ventricose, the aperture destitute of hairs; both sides of it are furnished with rotatory cilia, and the tail is biphyllos.
37. The tremula has something of a conical shape; the mouth being divided into parts which are set with small spines; and a point projects from the tail.
38. The serita is muscular, pellucid, folding variously; the fore part truncated: round the margin are rows of hairs; but it has also stiffer hairs or spines continually vibrating, with which it draws in all animate and inanimate substances which it is able to manage.
39. The lacunulata is shaped like an inverted cone, the aperture lobated, the tail small and furnished with two bristles. When swimming, the rotatory organ may be discovered. It moves swiftly in an oblique direction.
40. The
Microscope 40. The constricta is of two kinds; viz, of a pale yellow and of a white colour. They move by fixing their tail to the place where they are, and then extending their body as much as possible; fixing the fore part to the place to which they intend to move, then drawing the hinder part to it, and so on. Sometimes they turn round about upon one of the points of their tail; at other times they spring forwards with a jerk. When at rest they open their mouths very wide.
41. The togata has a convex body, filled with molecules, and of a dark colour; the hinder part somewhat broader than the forepart; the latter ciliated, and the tail formed of two very thin pellucid spines, which are somewhat curved, and much longer than the body.
42. The rotatoria is the wheel animal described by Mr Baker; and of which an account is given under the article ANIMALCULE.
43. The foreata is commonly found in water, and has a cylindric body with a rotatory organ, consisting of a row of hairs at the apex: the tail is divided into two parts, turning a little inwards. When at rest it joins the segments of the tail, but opens them when in motion.
44. The catulus is commonly found in marshy waters. It is a little thick muscular animalcule, folding itself up: equally broad throughout, the body disfigured by longitudinal folds, winding in various directions. The anterior part is connected to the body by a little neck; and it occasionally shows a small rotatory organ. Its motion is rotatory, but in various directions.
45. The cunicula is cylindrical, the aperture plain, with a short articulated tail divided into two parts.
46. The filis has a large body, the apex of an equal thickness, obtuse, with rotatory filaments: the tail is acute, with two pellucid spines in length about one-third part of the body, alternately separating from and approaching one another.
47. The flentorea. See the article POLYPS.
48. The socialis, when considerably magnified, appears like a circle surrounded with crowns or ciliated heads, tied by small thin tails to a common centre, from whence they advance towards the circumference, where they turn very briskly, occasioning a kind of whirlpool, which brings its food. When one of them has been in motion for a time, it stops and another begins; sometimes two or three may be perceived in motion at once: they are frequently to be met with separate, with the tail sticking in the mud. The body contracts and dilates very much, so as sometimes to have the appearance of a cudgel, at others to assume almost a globular form.
49. The stofculosa appears to the naked eye like a yellow globule adhering to the ceratophyllon like a little flower or a heap of yellow eggs. When magnified, they are seen to consist of a congeries of animalcula constituting a sphere from a mouldy centre. They contract and extend their bodies either alone or in society, and excite a vortex in the water by means of a disc. When they quit the society and act singly, they may be observed to consist of a head, abdomen, and tail; the head being frequently drawn back into the abdomen so far that it cannot be seen, only exhibiting a broad kidney-shaped disc standing out. The abdo-
men is oblong, oval, and transparent; the tail sharp, Microscope twice as long as the abdomen, sometimes rough and annulated, or altogether smooth.
50. The citrina is found in stagnant water; the head full of molecules, round, every where of an equal size, and very transparent. Both sides of the orifice are ciliated, and each has a rotatory motion appearing sometimes without and sometimes within the edge of the mouth.
51. The pariformis is somewhat oval, with a very small retractile foot, which it can draw within itself.
52. The tuberosa has a broad upper part, the under part small, with two projections at the anterior end, furnished with a number of fibrillæ, which produce a current of water by their vibration, and thus collect food for the animal.
53. The ringens is pear-shaped, pellucid, the middle of the aperture convex, both sides ciliated, the pedicle four times shorter than the body. It can contract the orifice to an obtuse point.
54. The inclinans has a pendulous, pellucid, little head; the anterior part truncated, and occasionally contracting itself twice as short as the pedicle. It is shaped like a tobacco-pipe.
55. The marginata is erect, of the shape of a truncated egg; the pedicle is contained in a sheath.
56. The globularia is frequent among the cyclopa quadricorni. It has a small spherical head, the aperture of the mouth ciliated, the pedicle four times larger than the body, which it contracts into a spiral form.
57. The lunaris has a small goblet-shaped head, the margin of the orifice protuberant, ciliated on both sides, with undulating hairs, and the pedicle eight or ten times the length of the body. The pedicle extends itself as often as the mouth is opened, but is twisted up spirally when it is shut; and this is frequently repeated in a short space.
58. The convallaria is the same with the bell-animal mentioned by Mr Baker. See the article ANIMALCULE.
59. The nutans has a simple pedicle; twists itself spirally; is extremely slender, with a kind of cap on its head; the margin white and round, and seemingly encompassed with a lucid ring; the head diminishing towards the base.
60. The nebulifera is narrow at the base; open and truncated at the top; the margin seemingly surrounded with a ring: but, when the aperture is shut, the animalcule is of the shape of an egg, with a simple falcateous pedicle, considerably longer than the body, and commonly much bent back.
61. The annularis is visible to the naked eye; the head an inverted cone, convex when the mouth is shut, but truncated when it is open; with a protuberant edge; the pedicle simple, very long, thick, and, whiter at the top than any where else; the apex twisted spirally.—When contracted, it appears to be annulated.
62. The acinosia inhabits that whitish substance which often entirely covers plants, wood, shells, &c. When this substance is examined by a microscope, it appears to be wholly composed of living animals of the polype kind. See POLYPS.
63. The fasciculata has a rotatory organ, which may sometimes be seen projecting beyond the aperture; there is a little head at the apex, and the pedicle is twisted and very slender. A congealed green mass which is often found swimming about in ditches is composed of myriads of these animals, which are not visible to the naked eye, and when magnified appear like a bundle of green flowers.
64. The hians resembles a citron; the apex is truncated, the base narrow, and a gaping cleft is observable, descending from the apex to one third of the body.
65. The bellis is of a yellow colour, and much resembles the flower of a daisy; is ciliated round the margin of the head, and moves in a rotatory manner.
66. The gemella has a long pedicle, constantly furnished with two small heads.
68. The pyraria.
69. The anastatica.
70. The digitalis.
71. The polypina, when viewed through a small magnifier, they appear like so many little trees: the upper part, or heads, are egg shaped, the top truncated, the lower part filled with intestines; the branches thick set with little knobs.
72. The racemosa is only distinguished from the vorticella socialis by always adhering to the sides of the vessel in which it is placed. By the microscope, we discover a long pedicle sticking to the sides of the vessels, from which proceed an innumerable quantity of crystalline pellucid pearls; which, together with the stalk, are variously agitated in the water. Sometimes they move separately; sometimes they are drawn down to the root, and in a moment expanded again.
A contractile worm, covered with a shell, and furnished with rotatory cilia.
1. The striatus has an oblong, pellucid shell, capable of altering its figure. The apex is truncated, with six small teeth on the edge of it, twelve longitudinal streaks down the back, the base obtuse and smooth. The teeth are occasionally protruded or retracted; and there are two small spines or horns on the other side of the shell. The animal itself is of a yellow colour, crystalline, and muscular; now and then putting out from the apex two or three little bundles of playing hairs, the two lateral ones shorter than that in the middle: on the under side we may observe a forked deglutitory muscle, and two rigid points when the apex is drawn in. It is found in sea-water.
2. The squamula has an univalve orbicular shell, a truncated apex, four teeth, smooth base, and no tail.
3. The pala is of a yellow colour; univalved, with an oblong excavated shell; four long teeth at the apex; a smooth base.
4. The bipalium is univalved, the shell oblong and inflected, ten teeth at the apex, the base smooth, and a spurious tail.
5. The patina is extremely bright and splendid, has a large body, a crystalline and nearly circular shell, without either incision or teeth, only towards the apex it falls in so as to form a smooth notch. A double glittering organ, with ciliated edges, projects from the apex; both of them of a conical figure, and standing
as it were upon a pellucid substance, which is divided into two lobes, between which and the rotatory organ there is a silver-coloured crenulated membrane. Two small claws may likewise be discovered near the mouth.
6. The elypeatus is univalved, the shell oblong, apex notched, the tail naked, and base smooth.
7. The lamellaris is univalved; the shell extending considerably beyond the body; the base divided into three small horns, with two hairs at the end of the tail.
8. The patella is found in marshy water in the winter-time. It is univalved, the shell oval, plain, crystalline, with the anterior part terminating in two acute points on both sides, though the intervening space is commonly filled up with the head of the animal. By these points it fastens itself, and whirls about the body erect. The rotatory cilia are perceived with great difficulty.
9. The bractea is univalved, the shell somewhat orbicular, apex lunated, base smooth, and the tail furnished with two spines.
10. The plicatilis is univalved, with an oblong shell, the apex hairy, and base notched.
11. The ovalis is bivalved; the shell flattened, apex notched, a hollow part at the base, the tail formed of two tufts of hair.
12. The tripos is bivalved, the apex of the shell beardless, three horns at the base, and double tail. It fixes itself to objects by the filaments of the tail.
13. The dentatus is bivalved, with an arched shell; the apex and base are both toothed, and the tail formed of two spines.
14. The mucronatus is bivalved, somewhat of a square form; the base and apex pointed; the tail consisting of two spines.
15. The uncinatus is one of the smallest bivalved animals; the apex and anterior part round, the hinder part straight, terminating in a point, furnished with a hook on the fore part, a small rotatory organ, a long tail composed of joints, and divided at the end into two bristles. It can open its shell both at the fore and hind part.
16. The cirratus is larger than the preceding; ventricose, somewhat transparent, the head conical, with a bundle of hairs on both sides; and it has likewise a rotatory organ.
17. The passus has a cylindric shell, with two long pendulous locks of hair proceeding from the front, the tail consisting of a single bristle.
18. The quadratus has a quadrangular shell, with two small teeth at the apex, two horns proceeding from the base, and no tail.
19. The impressus has a quadrangular shell, a smooth undivided apex; obtuse base; notched margin; and flexuous tail.
20. The urceolaris. See POLYPE.
21. The brachionus Bakeri has a ventricose shell, four teeth at the apex, two horns at the base, and a long tail terminating in two short points. The horns are frequently extended; and the circular end of each is furnished with a tuft of little hairs, which sometimes move in a vibratory manner, at other times have a rotatory motion. Mr Muller has also discovered in this creature two small feelers and a tongue.
22. The patulus has a ventricose shell, with eight teeth.
Microscope teeth at the apex; the base lunated, or hollowed into the form of a crescent, and furnished with four horns; the tail short, with two small points at the end.
markable, that though in general they avoid one another, it is not uncommon, when one is nearly divided, to see another push itself upon the small neck which joins the two bodies in order to accelerate the separation.—Others, when about to multiply, fix themselves to the bottom of the water; then becoming first oblong, and afterwards round, turn rapidly as on a centre, but perpetually varying the direction of their rotatory motion. In a little time, two lines forming a cross are perceived; after which the spherule divides into four, which grow, and are again divided as before. A third kind multiply by a longitudinal division, which in some begins in the fore-part, in others in the hind-part; and from others a small fragment detaches itself, which in a short time assumes the shape of the parent animalcule. Lastly, others propagate in the same manner as the more perfect animals.
In our observations under the article ANIMALCULE, we suggested some doubts whether all those minute bodies which go under the name of animalcules really do enjoy animal life; or whether they are not in many cases to be accounted only inanimate and exceedingly minute points of matter actuated by the internal motion of the fluid. This has also been the opinion of others: but to all hypotheses of this kind Mr Adams makes the following reply. "From what has been said, it clearly appears, that their motions are not purely mechanical, but are produced by an internal spontaneous principle; and that they must therefore be placed among the class of living animals, for they possess the strongest marks and the most decided characters of animation; and, consequently, that there is no foundation for the supposition of a chaotic and neutral kingdom, which can only have derived its origin from a very transient and superficial view of these animalcules.—It may also be further observed, that as we see that the motions of the limbs, &c. of the larger animals, are produced by the mechanical construction of the body, and the action of the soul thereon, and are forced by the ocular demonstration which arises from anatomical dissection to acknowledge this mechanism which is adapted to produce the various motions necessary to the animal; and as, when we have recourse to the microscope, we find those pieces which had appeared to the naked eye as the primary mechanical causes of particular motions, to consist themselves of lesser parts, which are the causes of motion, extension, &c. in the larger; when the structure therefore can be traced no farther by the eye, or by the glasses; we have no right to conclude that the parts which are invisible are not equally the subject of mechanism: for this would be only to assert, in other words, that a thing may exist because we see and feel it, and have no existence when it is not the object of our senses.—The same train of reasoning may be applied to microscopic insects and animalcula: we see them move; but because the muscles and members which occasion these motions are invisible, shall we infer that they have not muscles, with organs appropriated to the motion of the whole and its parts? To say that they exist not because we cannot perceive them, would not be a rational conclusion. Our senses are indeed given us that we may comprehend some effects; but then we have also a mind, with reason, bestowed upon
These are the different kinds of animalcules which have yet been discovered. To what is said of them in general under the article ANIMALCULE, we shall here add the following observations from Mr Adams.—"How many kinds of these invisibles there may be (says he) is yet unknown; as they are discerned of all sizes, from those which are barely invisible to the naked eye, to such as resist the force of the microscope as the fixed stars do that of the telescope, and with the greatest powers hitherto invented appear only as so many moving points. The smallest living creatures our instruments can show, are those which inhabit the waters; for though animalcula equally minute may fly in the air, or creep upon the earth, it is scarce possible to get a view of them; but as water is transparent, by confining the creatures within it we can easily observe them by applying a drop of it to the glasses.
"Animalcules in general are observed to move in all directions with equal ease and rapidity, sometimes obliquely, sometimes straight forward; sometimes moving in a circular direction, or rolling upon one another, running backwards and forwards through the whole extent of the drop, as if diverting themselves; at other times greedily attacking the little parcels of matter they meet with. Notwithstanding their extreme minuteness, they know how to avoid obstacles, or to prevent any interference with one another in their motions: sometimes they will suddenly change the direction in which they move, and take an opposite one; and, by inclining the glass on which the drop of water is, as it can be made to move in any direction, so the animalcules appear to move as easily against the stream as with it. When the water begins to evaporate, they flock towards the place where the fluid is, and show a great anxiety and uncommon agitation of the organs with which they draw in the water. These motions grow languid as the water fails, and at last cease altogether, without a possibility of renewal if they be left dry for a short time. They sustain a great degree of cold as well as insects, and will perish in much the same degree of heat that destroys insects. Some animalcules are produced in water at the freezing point, and some insects live in snow.—By mixing the least drop of urine with the water in which they swim, they instantly fall into convulsions and die.
"The same rule seems to hold good in those minute creatures, which is observable in the larger animals, viz. that the larger kinds are less numerous than such as are smaller, while the smallest of all are found in such multitudes, that there seem to be myriads for one of the others. They increase in size, like other animals, from their birth until they have attained their full growth; and when deprived of proper nourishment, they in like manner grow thin and perish."
The modes of propagation among these animalcules are various, and the observation of them is extremely curious. Some multiply by a transverse division, as is observed under the article ANIMALCULE: and it is re-
Microscopes upon us, that, from the things which we do perceive with our senses, we may deduce the nature of those causes and effects which are imperceptible to the corporeal eye."
Leaving these speculations however, we shall now proceed to give a particular
Explanation of the figures of the various animals, with their parts, &c., &c. represented in the plates.
Plate CCXII.
Fig. 32, 33, represent the eggs of the phakena neustria, as they are taken from the tree to which they adhere, and magnified by the microscope. The strong ground-work visible in many places, shows the gum by which they are fastened together; and this connection is strengthened by a very tenacious substance interposed between the eggs, and filling up the vacant spaces. Fig. 34, shows a vertical section of the eggs, exhibiting their oval shape.— Fig. 35, is an horizontal section through the middle of the egg. These eggs make a beautiful appearance through the microscope. The small figures a, b, c, represent the objects in their natural state, without being magnified.
Fig. 36, shows the larva of the musca chameleon, an aquatic insect. When viewed by the naked eye, it appears (as here represented) to be composed of twelve annular divisions, separating it into an head, thorax, and abdomen; but it is not easy to distinguish the two last parts from each other, as the intestines lie equally both in the thorax and abdomen. The tail is furnished with a fine crown or circle of hair b, disposed in the form of a ring, and by this means it is supported on the surface of the water, the head and body hanging down towards the bottom, in which posture it will sometimes remain for a considerable time without any motion.— When it has a mind to sink to the bottom, it closes the hairs of the ring, as in fig. 37. Thus an hollow space is formed, including a small bubble of air; by enlarging or diminishing which, it can rise or sink in the water at pleasure. When the bubble escapes, the insect can replace it from the pulmonary tubes, and sometimes considerable quantities of air may be seen to escape from the tail of the worm into the common atmosphere; which operation may easily be observed when the worm is placed in a glass of water, and affords an entertaining spectacle. The snout of this insect is divided into three parts, of which that in the middle is immovable; the other two, which grow from the sides of the middle one, are moveable, and vibrate like the tongues of lizards or serpents. In these lateral parts lies most of the creature's strength; for it walks upon them when out of the water, appearing to walk on its mouth, and to use it as the parrot does its beak to assist it in climbing.
The larva is shown fig. 38, as it appears through a microscope. It grows narrower towards the head, is largest about that part which we may call the thorax, converges all along the abdomen, and terminates at length in a sharp tail surrounded with hairs, as has already been mentioned. The twelve annular divisions are now extremely visible, and are marked by numbers in the plate. The skin appears somewhat hard, and resembling shagreen, being thick set with grains pretty equally distributed. It has nine holes, or spiracula, probably for the purpose of breathing, on each side;
but it has none of these on the tail division a, nor any Microscopically visible on the third from the head. In the latter, indeed, it has some very small holes concealed under the skin, near the place where the embryo wings of the future fly are hid. "It is remarkable (says Mr Adams) that caterpillars, in general, have two rings without these spiracula, perhaps because they change into flies with four wings, whereas this worm produces a fly with only two." The skin of the larva is adorned with oblong black furrows, spots of a light colour, and orbicular rings, from which there generally springs a hair; but only those hairs which grow on the insect's sides are represented in the figure. There are also some larger hairs here and there, as at c, c. The difference of colour, however, in this worm arises only from the quantity of grains in the same space; for where they are in very great numbers, the furrows are darker, and paler where they are less plentiful.
The head d is divided into three parts, and covered with a skin which has hardly any discernible grains.— The eyes are rather protuberant, and lie near the snout; on which last are two small horns at i, i. It is crooked, and ends in a sharp point as at f. The legs are placed near the snout between the sinuses in which the eyes are fixed. Each of these legs consists of three joints, the outermost of which is covered with stiff hairs like bristles g, g. From the next joint there springs a horny bone b, b, used by the insect as a kind of thumb: the joint is also composed of a black substance of an intermediate hardness between bone and horn; and the third joint is of the same nature. In order to distinguish these parts, those that form the upper sides of the mouth and eyes must be separated by means of a small knife; after which, by the assistance of the microscope, we may perceive that the leg is articulated by some particular ligaments, with the portion of the insect's mouth which answers to the lower jaw in the human frame. We may then also discern the muscles which serve to move the legs, and draw them up into a cavity that lies between the snout and those parts of the mouth which are near the horns i, i. The insect walks upon these legs, not only in the water, but on the land also. It likewise makes use of them in swimming, keeping its tail on the surface contiguous to the air, and hanging downward with the rest of the body in the water. In this situation, the only perceptible motion it has is in its legs, which it moves in a most elegant manner, from whence it is reasonable to conclude, that the most of this creature's strength lies in its legs, as we have already observed.
The snout of this larva is black and hard: the back part quite solid, and somewhat of a globular form; the front f sharp and hollow. Three membranaceous divisions may be perceived on the back part; by means of which, and the muscles contained in the snout, the creature can contract or expand it at pleasure.
The extremity of the tail is surrounded with thirty hairs, and the sides adorned with others that are smaller; and here and there the large hairs branch out into smaller ones, which may be reckoned single hairs. All these have their roots in the outer skin, which in this place is covered with rough grains, as may be observed by cutting it off and holding it against the light upon
Microscope upon a slip of glass. Thus also we find, that at the extremities of the hairs there are grains like those on the skin; and in the middle of the tail there is a small opening, within which are minute holes, by which the insect takes in and lets out the air it breathes. These hairs, however, are seldom disposed in such a regular order as is represented in fig. 38. unless when the insect floats with the body in the water, and the tail with its hairs a little lower than the surface, in which case they are disposed exactly in the order delineated in the plate. The least motion of the tail downward produces a concavity in the water; and it then assumes the figure of a wine-glass, wide at the top and narrow at the bottom. The tail answers the double purpose of swimming and breathing, and through it the insect receives what is the principle of life and motion to all animals. By means of these hairs also it can stop its motion when swimming, and remain suspended quietly without motion for any length of time. Its motions in swimming are very beautiful, especially when it advances with its whole body floating on the surface of the water after filling itself with air by the tail.— To set out, it first bends the body to the right or left, and then contracts it in the form of the letter S, and again stretches it out in a straight line: by thus contracting and then extending the body alternately, it moves on the surface of the water. It is very quiet, and is not disturbed by handling.
These creatures are commonly found in shallow standing waters in the beginning of June; but some years much more plentifully than others. They crawl on the grass and other plants which grow in such waters, and are often met with in ditches floating on the surface of the water by means of their tail, the head and thorax at the same time hanging down; and in this posture they turn over the clay and dirt with their snout and feet in search of food, which is commonly a viscous matter met with in small ponds and ditches. It is very harmless, though its appearance would seem to indicate the contrary. It is most easily killed for dissection by spirit of turpentine.
Fig. 39. shows in its natural size a beautiful insect, described by Linnæus under the name of Leucopis dorsifera, and which appears to be a kind of intermediate genus between a sphex and a wasp. The antennæ are black and cylindrical, increasing in thickness towards the extremity; the joint nearest the head is yellow; the head and thorax are black, encompassed with a yellow line, and furnished with a cross line of the same colour near the head. The scutellum is yellow, the abdomen black, with two yellow bands, and a deep spot of the same colour on each side between the bands. A deep polished groove extends down the back from the thorax to the anus, into which the sting turns and is deposited, leaving the anus very circular; a yellow line runs on each side of the sting.— The anus and whole body, when viewed with a small magnifier, appear punctuated; but when these points are seen through a large magnifier, they appear hexagonal. Fig. 40. shows the insect very much magnified. Fig. 41. gives a side view of it magnified in a smaller degree.
Fig. 42. shows an insect lately discovered by Mr John Adams of Edmonton, as he happened to be at
an inn. It was first seen by some labouring people Microscope who were there at the time, by whom it was conjectured to be a louse with unusually long horns, a mite, &c. Mr Adams hearing the debate, procured the insect; and having viewed it through a microscope, it presented the appearance exhibited in fig. 42. The insect seems to be quite distinct from the phalangium caneroides of Linnæus. The latter has been described by several authors, but none of their descriptions agree with this. The abdomen of this insect is more extended, the claws larger, and much more obtuse; the body of the other being nearly orbicular, the claws slender, and almost terminating in a point, more transparent, and of a paler colour. Mr Marham has one in his possession not to be distinguished from that represented in fig. 42, excepting only that it wants the break or dent in the claws, which is so conspicuous in this. He found that insect firmly fixed by its claws to the thigh of a large fly, which he caught on a flower in Essex in the first week of August, and from which he could not disengage it without great difficulty, and tearing off the leg of the fly. This was done upon a piece of writing paper; and he was surprised to see the little creature spring forward a quarter of an inch, and again seize the thigh with its claws, so that he had great difficulty in disengaging it. The natural size of this creature, which Mr Adams calls the lobster-insect, is exhibited at a.
Fig. 43. shows the insect named by M. de Geer Physapus, on account of the bladders at its feet, (Thrips physapus, Lin.). This insect is to be found in great plenty upon the flowers of dandelion, &c. in the spring and summer. It has four wings, two upper and two under ones (represented fig. 44.) but the two undermost are not to be perceived without great difficulty. They are very long; and fixed to the upper part of the breast, lying horizontally. Both of them are rather pointed towards the edges, and have a strong nerve running round them, which is set with a hair fringe tufted at the extremity. The colour of these wings is whitish: the body of the insect is black; the head small, with two large reticular eyes. The antennæ are of an equal size throughout, and divided into six oval pieces, which are articulated together.— The extremities of the feet are furnished with a membranaceous and flexible bladder, which it can throw out or draw in at pleasure. It presses this bladder against the substances on which it walks, and thus seems to fix itself to them; the bladder sometimes appears concave towards the bottom, the concavity diminishing as it is less pressed. The insect is represented of its natural size at b.
Fig. 45. represents the Cimex frutis of Linnæus, remarkable for very bright and elegantly disposed colours, though few in number. The head, prothorax, and thorax, are black: the thorax ornamented with yellow spots; the middle one large, and occupying almost one-third of the posterior part; the other two are on each side, and triangular. The scutellum has two yellow oblong spots, pointed at each end. The ground of the elytra is a bright yellow, spotted and striped with black. The nerves are yellow; and there is a brilliant triangular spot of orange, which unites the crustaceous and membranaceous.
Microscope ceous parts; the latter are brown, and clouded. It is found on the elm-tree in June. It is represented of its natural size at c.
Fig. 46. shows the Chrysomela asparagi of Linnæus, so called from the larva of the insect feeding upon that plant. It is a common insect, and very beautiful. It is of an oblong figure, with black antennæ, composed of many joints, nearly oval. The head is a deep and bright blue; the thorax red and cylindrical: the elytra are blue, with a yellow margin, and having three spots of the same colour on each; one at the base, of an oblong form, and two united with the margin: the legs are black; but the under side of the belly is of the same blue colour with the elytra and head. This little animal, when viewed by the naked eye, scarcely appears to deserve any notice; but when examined by the microscope, is one of the most pleasing opaque objects we have. It is found in June on the asparagus after it has run to feed; and it is shown of its natural size at d. De Geer says that it is very scarce in Sweden.
Fig. 47. shows an insect of a shape so remarkable, that naturalists have been at a loss to determine the genus to which it belongs. In the Fauna Suecica, Linnæus makes it an attelabus: but in the last edition of the Systema Naturæ, it is ranged as a meloe, under the title of the Meloe monoceros; though of this also there seems to be some doubt. The true figure of it can only be discovered by a very good microscope. The head is black, and appears to be hid or buried under the thorax, which projects forward like a horn: the antennæ are composed of many joints, and are of a dirty yellow colour, as well as the feet: the hinder part of the thorax is reddish, the fore-part black.—The elytra are yellow, with a black longitudinal line down the suture; there is a band of the same colour near the apex, and also a black point near the base, the whole animal being curiously covered with hair. The natural size of it is shown at e. It was found in May. Geoffroy says that it lives upon umbelliferous plants.
Fig. 48—53. exhibit the anatomy of the cossus caterpillar, which lives on the willow. The egg from which it proceeds is attached to the trunk of the tree by a kind of viscous juice, which soon becomes so hard that the rain cannot dissolve it. The egg itself is very small and spheroidal, and, when examined by the microscope, appears to have broad waving furrows running through the whole length of it, which are again crossed by close streaks, giving it the appearance of a wicker basket. It is not exactly known what time they are hatched; but as the small caterpillars appear in September, it is probable that the eggs are hatched some time in August. When small, they are generally met with under the bark of the tree to which the eggs were affixed; and an aqueous moisture, oozing from the hole through which they got under the bark, is frequently, though not always, a direction for finding them. These caterpillars change their colour but very little, being nearly the same when young as when old. Like many others, they are capable of spinning as soon as they come from the egg. They also change their skin several times; but as it is almost impossible to rear them under a glass, so it is very difficult to know exactly how often this moulting takes place.—Mr Adams conjectures that it is more frequently than
the generality of caterpillars do, some having been Microscopically observed to change more than nine times.
The cossus generally falls for some days previous to the moulting; during which time the fleshy and other interior parts of the head are detached from the old skull, and retire as it were within the neck. The new coverings soon grow on, but are at first very soft.—When the new skin and the other parts are formed, the old skin is to be opened, and all the members withdrawn from it; an operation naturally difficult, but which must be rendered more so from the soft and weak state of the creature at that time. It is always much larger after each change.
From Mr Lyonet's experiments, it appears, that the cossus generally passes at least two winters, if not three, before it assumes the pupa state. At the approach of winter, it forms a little case, the inside of which is lined with silk, and the outside covered with wood ground like very fine saw-dust. During the whole season it neither moves nor eats.
This caterpillar, at its first appearance, is not above one-twelfth of an inch long; but at last attains the length of two, and sometimes of three inches. In the month of May it prepares for the pupa state; the first care being to find a hole in the tree sufficient to allow the moth to issue forth; and if this cannot be found, it makes one equal in size to the future pupa. It then begins to form of wood a case or cone; uniting the bits, which are very thin, together by silk, into the form of an ellipsoid, the outside being formed of small bits of wood joined together in all directions; taking care, however, that the pointed end of the case may always be opposite to the mouth of the hole: having finished the outside of the case, it lines the inside with a silken tapestry of a close texture in all its parts, except the pointed end, where the texture is looser, in order to facilitate its escape at the proper time. The caterpillar then places itself in such a posture, that the head may always lie towards the opening of the hole in the tree or pointed end of its case. Thus it remains at rest for some time: the colour of the skin first becomes pale, and afterwards brown; the interior parts of the head are detached from the skull; the legs withdraw themselves from the exterior case; the body shortens; the posterior part grows small, while the anterior part swells so much, that the skin at last bursts; and, by a variety of motions, is pushed down to the tail; and thus the pupa is exhibited, in which the parts of the future moth may be easily traced.—The covering of the pupa, though at first soft, humid, and white, soon dries and hardens, and becomes of a dark purple colour: the posterior part is moveable; but not the fore-part, which contains the rudiments of the head, legs, and wings. The fore-part of the pupa is furnished with two horns, one above and the other under the eyes. It has also several rows of points on its back. It remains for some weeks in the case; after which the moth begins to agitate itself, and the points are then of essential service, by acting as a fulcrum, upon which it may rest in its endeavours to proceed forward, and not slip back by its efforts for that purpose.
The moth generally continues its endeavours to open the case for a quarter of an hour; after which, by redoubled efforts, it enlarges the hole, and presses forward.
Microscope ward until it arrives at the edge, where it makes a full stop, left by advancing further it should fall to the ground. After having in this manner reposed itself for some time, it begins to disengage itself entirely; and having rested for some hours with its head upwards, it becomes fit for action. Mr Marsham says, that it generally pushes one third of the case out of the hole before it halts.
The body of the caterpillar is divided into twelve rings, marked 1, 2, 3, &c. as represented in fig. 48. 49. 50. 51. each of which is distinguished from that which precedes, and that which follows, by a kind of neck or hollow; and, by forming boundaries to the rings, we make twelve other divisions, likewise expressed in the figures; but to the first of these the word ring is affixed, and to the second, division. To facilitate the description of this animal, M. Lyonet supposed a line to pass down through the middle of the back, which he called the superior line, because it marked the most elevated part of the back of the caterpillar; and another, passing from the head down the belly to the tail, he called the inferior line.
All caterpillars have a small organ, resembling an elliptic spot, on the right and left of each ring, excepting the second, third, and last; and by these we are furnished with a further subdivision of this caterpillar, viz. by lines passing through the spiracula, the one on the right side, the other on the left of the caterpillar. These four lines, which divide the caterpillar longitudinally into four equal parts, mark each the place under the skin which is occupied by a considerable viscous. Under the superior line lies the heart, or rather thread of hearts; over the inferior line, the spinal marrow; and the two tracheal arteries follow the course of the lateral lines. At equal distances from the superior and two lateral lines, we may suppose four intermediate lines. The two between the superior and lateral lines are called the intermediate superior; the two others opposite to them, and between the lateral and inferior lines, are called the intermediate inferior.
Fig. 48. 49. show the muscles of the caterpillar, arranged with the most wonderful symmetry and order, especially when taken off by equal strata on both sides, which exhibits an astonishing and exact form and correspondence in them. The figures show the muscles of two different caterpillars opened at the belly, and supposed to be joined together at the superior lines. The muscles of the back are marked by capitals; the gastric muscles by Roman letters; the lateral ones by Greek characters. Those marked are called, by M. Lyonet, dividing muscles, on account of their situation.
The caterpillar was prepared for dissection by being emptied, and the muscles, nerves, &c. freed from the fat in the manner formerly directed: after which the following observations were made.
The muscle A in the first ring is double; the anterior one being thick at top, and being apparently divided into different muscles on the upper side, but without any appearance of this kind on the under side. One insertion is at the skin of the neck towards the head; the other is a little above; and that of the second muscle A is a little below the first spiraculum, near which they are fixed to the skin.
The muscle marked is long and slender, fixed by Microscope its anterior extremity under the gastric muscles and of the first ring, to the circumflex scale of the base of the lower lip. It communicates with the muscle of the second ring, after having passed under some of the arteries, and introduced itself below the muscle .
The muscle is so tender, that it is scarce possible to open the belly of the caterpillar without breaking it. It is sometimes double, and sometimes triple. Anteriorly it is fixed to the posterior edge of the side of the parietal scale, the lower fixture being at the middle of the ring near the inferior line.
There are three muscles marked ; the first affixed at one extremity near the lower edge of the upper part of the parietal scale; the other end divides itself into three or four tails, fixed to the skin of the caterpillar under the muscle . The anterior part of the second is fixed near the first; the anterior part of the third a little under the first and second, at the skin of the neck under the muscle A. These two last passing over the cavity of the first pair of limbs, are fixed by several tails to the edge opposite to this cavity. In this subject there are two muscles marked , but sometimes there is only one anteriorly; they are fixed to the lower edge of the parietal scale, the other ends being inserted in the first fold of the skin of the neck on the belly-side. Fig. 50. best represents the muscles and ; as in that figure they do not appear injured by any unnatural connection.
In the second and four following rings we discern two large dorsal muscles A and B. In the 7th, 9th, and 10th rings are three, A, B, and C; in the 11th are four, A, B, C, and D; and in the anterior part of the 12th ring are five, A, B, C, D, and E. All these ranges of muscles, however, as well as the gastric muscles , , , , appear at first sight only as a single muscle, running nearly the whole length of the caterpillar; but when this is detached from the animal, it is found to consist of so many distinct muscles, each consisting only of the length of one of the rings, their extremities being fixed to the division of each ring, excepting the middle muscle , which, at the 6th, 7th, 8th, and 9th rings, has its insertions rather beyond the division. Each row of muscles appears as one, because they are closely connected at top by some of the fibres which pass from one ring to the other.
The muscles A, which are 12 in number, gradually diminish in breadth to the lower part of the last ring: at the 8th and three following divisions they communicate with the muscles B, and at the 11th with D. In the lower part of the last ring, A is much broader than it was in the preceding ring; one extremity of it is contracted, and communicates with B; the lower insertion being at the membrane I, which is the exterior skin of the fecal bag. The muscles A and B, on the lower part of the last ring, cannot be seen until a large muscle is removed, which on one side is fixed to the subdivision of the ring and on the other to the fecal bag.
The right muscles B, which are also 12 in number, begin at the second ring, and grow larger from thence to the seventh. They are usually narrower from thence to the 12th; the deficiency in width be-
Microscope ing supplied by the six muscles C, which accompany it from the 7th to the subdivision of the 12th ring. The muscles B and C communicate laterally with the 8th, 11th, and 12th divisions. C is wanting at the subdivision of the 12th; its place being here supplied by B, which becomes broader at this part.
The first of the three floating muscles V originates at the first ring, from whence it introduces itself under N, where it is fixed, and then subdivides, and hides itself under other parts. The second begins at the second division, being fixed to the anterior extremity B of the second ring; from thence directing itself towards the stomach; and, after communicating with the case of the corpus crassum, it divides, and spreads into eight muscles which run along the belly. The third begins at the third division, originating partly at the skin, and partly at the junction of the muscles B of the second and third ring. It directs itself obliquely towards the belly, meeting it near the third spiraculum; and branching from thence, it forms the oblique muscles of some of the viscera.
The thin, long, muscle , which is at the subdivision of the last ring, and covers the anterior insertion of the muscle () where the ring terminates, is single. It begins at one extremity of the muscle (); at the fore-part of the ring runs along the subdivision round the belly of the caterpillar, and finishes, on the other side, at the extremity of a similar muscle C.
Fig. 49. shows the dorsal muscles of the cossus. To view which in an advantageous manner, we must use the following mode of preparation.
1. All the dorsal muscles, 35 in number, must be taken out, as well as the seven lateral ones already described.
2. All the straight muscles of the belly must be taken away, as well as the muscular roots (), and the ends of the gastric muscles (), which are at the third and fourth divisions.
3. At the second division the muscle must be removed; only the extremities being left to show where it was inserted.
The parts being thus prepared, we begin at the third ring; where there are found four dorsal muscles C, D, E, and F. The first one C, is inserted at the third division, under the muscles and , where it communicates by means of some fibres with the muscle of the second ring; proceeding from thence obliquely towards the intermediate superior line, and is fixed at the fourth division. As soon as C is retrenched, the muscle D is seen; which grows wider from the anterior extremity: it lies in a contrary direction to the muscle C, and is inserted into the third and fourth divisions. The muscle E lies in the same direction as the muscle C, but not so obliquely: the lower insertion is at the fourth division; the other at the third, immediately under C. The muscle F is nearly parallel to D which joins it; the first insertion is visible, but the other is hid under the muscles E and G at the fourth division.
In the eight following rings, there are only two dorsal muscles; and of these D is the only one that is completely seen. It is very large, and diminishes gradually in breadth from one ring to the other, till it comes to the last, sending off branches in some
places.—E is one of the strait muscles of the back; Microscope and is inserted under the dividing muscles , at the divisions of its own ring.
On the anterior part of the 12th ring there are three dorsal muscles, D, E, and F. D is similar to that of the preceding ring, marked also D, only that it is no more than half the length; terminating at the subdivision of its own ring. E is of the same length, and differs from the muscle E of the preceding ring only in its direction. F is parallel to E, and shorter than it; its anterior end does not reach the twelfth division.
On the posterior part there is only one dorsal muscle, fastened by some short ones to the subdivision of the last ring, traversing the muscles ; and being fixed there as if designed to strengthen them, and to vary their direction.— is a single muscle, of which the anterior insertion is visible, the other end being fixed to the bottom of the foot of the last leg; its use is to move the foot. The anterior part of the muscle branches into three or four heads, which cross the superior line obliquely, and are fixed to the skin a little above it. The other end is fastened to the membrane T.
Fig. 50. and 51. show the muscles of the caterpillar when it is opened at the back. The preparation for this view is to disengage the fat and other extraneous matter, as before directed.
The first ring has only two gastric muscles () and (): the former is broad, and has three or four little tails: the first fixture is at the base of the lower lip, from whence it descends obliquely, and is fixed between the inferior and lateral line. The small muscle () is fastened on one side to the first spiraculum; on the other, a little lower, to the intermediate inferior and lateral line; and seems to be an antagonist to the muscle P, which opens the spiracula. The posterior fixture of is under the muscle C, near the skin of the neck: is fixed a little on the other side of C, at the middle of the ring.
In the second ring there are three gastric muscles, , , and : and are fixed at the folds which terminate the ring; but only the anterior part of is fixed there. The muscle is triple, and in one of the divisions separated into two parts; that marked comes nearer the inferior line, and is fixed a little beyond the middle of the ring, where the corresponding muscle of the opposite side is forked to receive it.
In the third ring, the muscle , which was triple in the foregoing ring, is only double here, that part which is nearest the inferior line being broadest: it has three tails, of which only two are visible in the figure. It is exactly similar to that of the preceding ring; and is crossed in the same manner by the muscle from the opposite side of the ring.
Throughout the eight following rings, the muscle which runs through them all is very broad and strong. The anterior part of it is fixed at the intermediate inferior line, on the fold of the first division of the ring: the other part is fixed beyond the lower division; with this difference, that at the 10th and 11th rings it is fixed at the last fold of its ring; whereas, in the others it passes over that ring, and is inserted into the skin of the following one. In all these,
Microscope these, the first extremity of the muscle g is fastened to the fold which separates the ring from the preceding one, and is parallel to f, and placed at the side of it. The six first muscles marked g, are forked; that of the fourth ring being more so than the rest, nor does it unite till near its anterior insertion. The longest tail lays hold of the following, and is inserted near the inferior line; the other inserts itself near the same line, at about the middle of its own ring. The two last do not branch out; but terminate at the divisions, without reaching the following ring. The muscle b, placed at the side of f, has nearly the same direction, and finishes at the folds of the ring.
The anterior part of the 12th ring has only one gastric muscle, marked e: it is placed on the intermediate inferior line; and is inserted at the folds of the upper division, and at the subdivision of this ring. The lower part has a larger muscle marked c, with several divisions; one placed under b, with one extremity fixed near the lateral line, at the subdivision of its ring; the other to the fecal bag, a little lower than the muscle b.
In fig. 51. all the gastric muscles described in fig. 50. disappear, as well as those lateral and dorsal ones of which the letters are not to be found in this figure.
In the first ring are the gastric muscles, e, f, g, which are best seen here: the first is narrow and long, passing under and crossing f: one of its insertions is at the lower line, the other at the lateral, between the spiraculum and neck: f is short, broad, and nearly straight, placed along the intermediate line; but between it and the lateral it passes under e, and is fixed to the fold of the skin which goes from the one bag to the other; the lower insertion is near the second division. There are sometimes three muscles of those marked g, and sometimes four: the lower parts of them are fixed about the middle of the ring, and the anterior parts at the fold of the skin near the neck. The muscles i and b are fixed to the same fold; the other end of b being fixed under the muscle ii, near the spiraculum. Above the upper end of f, a muscular body, g, may be seen. It is formed by the separation of two floating muscles.
The second ring has six gastric muscles, k, l, m, n, o, p. The first is a large oblique muscle, with three or four divisions placed at the anterior part of the ring: the head is fixed between the inferior line and its intermediate one, at the fold of the second division; from whence it crosses the inferior line and its corresponding muscle, terminating to the right and left of the line. i is a narrow muscle, whose head is fixed to the fold of the second division; the tail of it lying under n, and fastened to the edge of the skin that forms the cavity for the leg. The two muscles marked m have the same obliquity, and are placed the one on the other: the head is inserted in the skin under the muscle o, and communicates by a number of fibres with the tail of the muscle g; the other end is fixed to the intermediate inferior line at the fold of the third division. The large and broad muscle n, covers the lower edge of the cavity of the limb, and the extremity of the tail of l. It is fixed first at the skin, near the intermediate line, from whence it goes
in a perpendicular direction towards m, and introduces itself under o and m, where it is fixed. The muscle o is narrow and bent, and covers the edge of the cavity of the leg for a little way; one end terminating there, and the other finishing at the third division near m. That marked p is also bent: it runs near the anterior edge of the cavity of the leg; one end meets the head of o, the other end terminates at a raised fold near the inferior line. There is a triangular muscle on the side of the lateral muscle o, similar to that marked g in the following ring: in this figure it is entirely concealed by the muscle m.
The third ring has no muscle similar to m; that marked k differs only from that of the second ring in being crossed by the opposite muscle. Those marked l, n, o, p, are similar to those of the preceding one. The muscle q is triangular; the base is fastened to the last fold of the ring; on the lower side it is fixed to the muscle o, the top to the skin at the edge of the cavity for the leg.
The eight following rings have the gastric muscles, i, k, l, and m. The muscle i is quite straight, and placed at some distance from the inferior line: it is broad at the fourth ring, but diminishes gradually in breadth to the 11th. In the fourth it is united; but divides into two heads, which divaricate in the following rings. In the six next rings these heads are fixed nearly at the same place with a and f; and in the other two it terminates at the fold of the ring. The anterior insertion of the first and last is at the fold where the ring begins: that of the six others is somewhat lower under the place where the muscle i terminates. The lower part of the oblique muscle k is inserted in the skin near i; the upper part at the intermediate inferior muscle upon the fold which separates the following ring, but is wanting in the 11th. The muscle l is large, and co-operates with M: in the opening and shutting the spiraculum, one of its fixtures is near the intermediate inferior line, at about the same height as i. The tail terminates a little below the spiraculum.
The twelfth ring has only the single gastric muscle d, which is a bundle of six, seven, or eight muscles: the first fixture of these is at the subdivision of the ring near the inferior line: one or two cross this, and at the same time the similar muscles of the opposite side. Their fixture is at the bottom of the foot; and their office is to assist the muscle a in bringing back the foot, and to loosen the claw from what it lays hold of. One of the insertions of this muscle a is observed in this figure near d, the other near the subdivision of the ring.
Fig. 52. and 53. show the organization of the head of the colossus, though in a very imperfect manner, as M. Lyonet found it necessary to employ seventy figures to explain it fully. The head is represented as it appears when separated from the fat, and disengaged from the neck. HH are the two palpi. The truncated muscles D belong to the lower lip, and assist in moving it. K shows the two ganglions of the neck united. II are the two vessels which assist in spinning the silk. L, the oesophagus. M, the two dissolving vessels. The Hebrew characters אבדד show the continuation of the four cephalic arteries. In fig. 52. the ten abductor muscles of the jaw
Microscope are represented by SS, TT, VV, and Z. Four occipital muscles are seen in fig. 53. under ee and ff. At a k is represented a nerve of the first pair belonging to the ganglion of the neck; b is a branch of this nerve.
Fig. 54. exhibits the nerves as seen from the under part; but excepting in two or three nerves, which may be easily distinguished, only one of each pair is drawn, in order to avoid confusion. The nerves of the first ganglion of the neck are marked by capital letters, those of the ganglion (a) of the head by Roman letters; the nerves of the small ganglion by Greek characters. Those of the frontal ganglion, except one, by numbers.
The muscles of the cossus have neither the colour nor form of those of larger animals. In their natural state they are soft, and of the consistency of a jelly. Their colour is a greyish blue, which, with the silver-coloured appearance of the pulmonary vessels, form a glorious spectacle. After the caterpillar has been soaked for some time in spirit of wine, they lose their elasticity and transparency, becoming firm, opaque, and white, and the air-vessels totally disappear. The number of muscles in a caterpillar is very great. The greatest part of the head is composed of them, and there is a vast number about the oesophagus, intestines, &c. the skin is, as it were, lined by different beds of them, placed the one under the other, and ranged with great symmetry. M. Lyonet has been able to distinguish 228 in the head, 1647 in the body, and 2066 in the intestinal tube, making in all 4041.
At first sight the muscles might be taken for tendons, as being of the same colour, and having nearly the same lustre. They are generally flat, and of an equal size throughout; the middle seldom differing either in colour or size from either of the extremities. If they are separated, however, by means of very fine needles, in a drop of some fluid, we find them composed not only of fibres, membranes, and air-vessels, but likewise of nerves; and, from the drops of oil that may be seen floating on the fluid, they appear also to be furnished with many unctuous particles. Their ends are fixed to the skin, but the rest of the muscle is generally free and floating. Several of them branch out considerably; and the branches sometimes extend so far, that it is not easy to discover whether they are distinct and separate muscles or parts of another. They are moderately strong; and those which have been soaked in spirit of wine, when examined by the microscope, are found to be covered with a membrane which may be separated from them; and they appear then to consist of several parallel bands lying longitudinally along the muscle, which, when divided by means of fine needles, appear to be composed of still smaller bundles of fibres lying in the same direction; which, when examined by a powerful magnifier, and in a favourable light, appear twisted like a small cord. The muscular fibres of the spider, which are much larger than those of the caterpillar, consist of two different substances, one soft and the other hard; the latter being twisted round the former spirally, and thus giving it the twisted appearance just mentioned.
There is nothing in the caterpillar similar to the brain in man. We find indeed in the head of this
insect a part from which all the nerves seem to proceed; but this part is entirely unprotected, and so small, that it does not occupy one fifth part of the head: the surface is smooth, and has neither lobes nor any anfractuosity like the human brain. But if we call this a brain in the caterpillar, we must say that it has thirteen: for there are twelve other such parts following each other in a straight line, all of them of the same substance with that in the head, and nearly of the same size; and from them, as well as from that in the head, the nerves are distributed thro' the body.
The spinal marrow in the cossus goes along the belly; is very small, forking out at intervals, nearly of the same thickness throughout, except at the ganglions, and is not inclosed in any case. It is by no means so tender as in man; but has a great degree of tenacity, and does not break without a considerable degree of tension. The substance of the ganglions differs from that of the spinal marrow, as no vessels can be discovered in the latter; but the former are full of very delicate ones. There are 94 principal nerves, which divide into innumerable ramifications.
The cossus has two large tracheal arteries, creeping under the skin close to the spiracula; one at the right and the other at the left side of the insect, each of them communicating with the air by means of nine spiracula. They are nearly as long as the whole caterpillar; beginning at the first spiraculum, and extending somewhat farther than the last; some branches also extending quite to the extremity of the body. Round each spiraculum the trachea pushes forth a great number of branches, which are again divided into smaller ones, and these further subdivide and spread through the whole body of the caterpillar. The tracheal artery, with all its numerous ramifications, are open elastic vessels, which may be pressed close together, or drawn out considerably, but return immediately to their usual size when the tension ceases. They are naturally of a silver colour, and make a beautiful appearance. This vessel, with its principal branches, is composed of three coats, which may be separated from one another. The outmost is a thick membrane furnished with a great variety of fibres, which describe a vast number of circles round it, communicating with each other by numerous shoots. The second is very thin and transparent, without any particular vessel being distinguishable in it. The third is composed of fealy threads, generally of a spiral form; and so near each other as scarcely to leave any interval. They are curiously united with the membrane which occupies the intervals; and form a tube which is always open, notwithstanding the flexure of the vessel. There are also many other peculiarities in its structure. The principal tracheal vessels divide into 1326 different branches.
The heart of the cossus is very different from that of larger animals, being almost as long as the animal itself. It lies immediately under the skin at the top of the back, entering the head, and terminating near the mouth. Towards the last rings of the body it is large and capacious, diminishing very much as it approaches the head, from the fourth to the twelfth division. On both sides, at each division, it has an appendage, which partly
Plate CCCV.
Fig. 62.
Fig. 64.
Fig. 61.
Fig. 63.
Fig. 66.
Fig. 60.
A. Holl. Pin. Mal. sculptor fecit.
Microscope partly covers the muscles of the back, but which, growing narrower as it approaches the lateral line, it forms a number of irregular lozenge-shaped bodies.—This tube, however, seems to perform none of the functions of the heart in larger animals, as we find no vessel opening into it which answers either to the aorta or vena cava. It is called the heart, because it is generally filled with a kind of lymph, which naturalists have supposed to be the blood of the caterpillar; and because in all caterpillars which have a transparent skin, we may perceive alternate regular contractions and dilatations along the superior line, beginning at the eleventh ring, and proceeding from ring to ring, from the fourth; whence this vessel is thought to be a string or row of hearts. There are two white oblong bodies which join the heart near the eighth division; and these have been called reniform bodies, from their having somewhat of the shape of a kidney.
The most considerable part of the whole caterpillar with regard to bulk is the corpus crassum. It is the first and only substance that is seen on opening it. It forms a kind of sheath which envelopes and covers all the entrails, and, introducing itself into the head, enters all the muscles of the body, filling the greatest part of the empty spaces in the caterpillar. It very much resembles the configuration of the human brain, and is of a milk-white colour.
The oesophagus descends from the bottom of the mouth to about the fourth division. The fore-part, which is in the head, is fleshy, narrow, and fixed by different muscles to the crustaceous parts of it; the lower part, which passes into the body, is wider, and forms a kind of membranaceous bag, covered with very small muscles; near the stomach it is narrower, and, as it were, confined by a strong nerve fixed to it at distant intervals. The ventricle begins a little above the fourth division, where the oesophagus ends, and finishes at the tenth. It is about seven times as long as broad; and the anterior part, which is broadest, is generally folded. These folds diminish with the bulk as it approaches the intestines; the surface is covered with a great number of aerial vessels, and opens into a tube, which M. Lyonet calls the large intestine.—There are three of these large tubes, each of which differs so much from the rest, as to require a particular name to distinguish it from them.
The two vessels from which the cossus spins its silk are often above three inches long, and are distinguished into three parts; the anterior, intermediate, and posterior. It has likewise two other vessels, which are supposed to prepare and contain the liquor for dissolving the wood on which it feeds.
Plate CCCIV. Fig. 55. shows the wing of an earwig magnified; a represents it of the natural size. The wings of this insect are so artificially folded up under short cases, that few people imagine they have any. Indeed, they very rarely make use of their wings. The cases under which they are concealed are not more than a sixth part of the size of one wing, though a small part of the wing may be discovered, on a careful inspection, projecting from under them. The upper part of the wing is crustaceous and opaque, but the under part is beautifully transparent. In putting up their wings, they first fold back the parts AB, and then shut up the ribs like a fan; the strong muscles used for this purpose being seen at the upper part of the figure. Some of
the ribs are extended from the centre to the outer edge; others only from the edge about half way: but they are all united by a kind of band, at a small but equal distance from the edge; the whole evidently contrived to strengthen the wing, and facilitate its various motions. The insect itself differs very little in appearance in its three different states. De Geer asserts, that the female hatches eggs like a hen, and broods over her young ones as a hen does.
Fig. 56. represents a wing of the Hemerobius perla magnified. It is an insect which seldom lives more than two or three days.—The wings are nearly of a length, and exactly similar to one another. They are composed of fine delicate nerves, regularly and elegantly disposed as in the figure, beautifully adorned with hairs, and lightly tinged with green. The body is of a fine green colour; and its eyes appear like two burnished beads of gold, whence it has obtained the name of golden eye. This insect lays its eggs on the leaves of the plum or the rose tree; the eggs are of a white colour, and each of them fixed to a little pedicle or foot-stalk, by which means they stand off a little from the leaf, appearing like the fructification of some of the mosses. The larva proceeding from these eggs resembles that of the coccinella or lady-cow, but is much more handsome. Like that, it feeds upon aphides or pucerons, sucking their blood, and forming itself a case with their dried bodies; in which it changes into the pupa state, from whence they afterwards emerge in the form of a fly.
Fig. E, F, I, represent the dust of a moth's wing magnified. This is of different figures in different moths. The natural size of these small plumes is represented at H.
Fig. 57. shows a part of the cornea of the libellula magnified. In some positions of the light, the sides of the hexagons appear of a fine gold colour, and divided by three parallel lines. The natural size of the part magnified is shown at b.
Fig. 58. shows the part c of a lobster's cornea magnified.
Fig. 59. shows one of the arms or horns of the lepas antifer, or barnacle, magnified; its natural size being represented at d. Each horn consists of several joints, and each joint is furnished on the concave side of the arm with long hairs. When viewed in the microscope, the arms appear rather opaque; but they may be rendered transparent, and become a most beautiful object, by extracting out of the interior cavity a bundle of longitudinal fibres, which runs the whole length of the arm. Mr Needham thinks that the motion and use of these arms may illustrate the nature of the rotatory motion in the wheel-animal. In the midst of the arms is an hollow trunk, consisting of a jointed hairy tube, which incloses a long round tongue that can be pushed occasionally out of the tube or sheath, and retracted occasionally. The mouth of the animal consists of six laminae, which go off with a bend, indented like a saw on the convex edge, and by their circular disposition are so ranged, that the teeth, in the alternate elevation and depression of each plate, act against whatever comes between them. The plates are placed together in such a manner, that to the naked eye they form an aperture not much unlike the mouth of a contracted purse.
Fig. 60. shows the apparatus of the Tabanus or Gaddy, Plate CCCV.
Microscope fly, by which it pierces the skin of horses and oxen, in
order to suck their blood. The whole is contained in a fleshy case, not expressed in the figure. The feelers aa are of a spongy texture and grey colour, covered with short hairs. They are united to the head by a small joint of the same substance. They defend the other parts of the apparatus, being laid upon it side by side whenever the animal stings, and thus preserve it from external injury. The wound is made by the two lancets bb and B, which are of a delicate structure, but very sharp, formed like the dissecting knife of an anatomist, growing gradually thicker to the back.—The two instruments cc and C, appear as if intended to enlarge the wound, by irritating the parts round it; for which they are jagged or toothed. They may also serve, from their hard and horny texture, to defend the tube e E, which is of a softer nature, and tubular, to admit the blood, and convey it to the stomach. This part is totally enclosed in a line d D, which entirely covers it. These parts are drawn separately at B, C, D, E. De Geer observes, that only the females suck the blood of animals; and Reaumur informs us, that having made one, that had sucked its fill, disgorge itself, the blood it threw up appeared to him to be more than the whole body of the insect could have contained. The natural size of this apparatus is shown at f.
Fig. 61. shows a bit of the skin of a lump-fish (Cyclopterus) magnified. When a good specimen of this can be procured, it forms a most beautiful object. The tubercles exhibited in the figure probably secrete an unctuous juice.
Fig. 62. shows the scale of a sea-perch found on the English coast; the natural size is exhibited at b.
Fig. 63. is the scale of an haddock magnified; its natural size as within the circle.
Fig. 64. the scale of a parrot fish from the West Indies magnified; l the natural size of it.
Fig. 65. the scale of a kind of perch in the West Indies magnified; l the natural size of the scale.
Fig. 66. part of the skin of a sole fish, as viewed through an opaque microscope; the magnified part, in its real size, shown at l.
The scales of fishes afford a great variety of beautiful objects for the microscope. Some are long; others round, square, &c. varying considerably not only in different fishes, but even in different parts of the same fish. Leeuwenhoek supposed them to consist of an infinite number of small scales or strata, of which those next to the body of the fish are the largest. When viewed by the microscope, we find some of them ornamented with a prodigious number of concentric flutings, too near each other, and too fine to be easily enumerated. These flutings are frequently traversed by others diverging from the centre of the scale, and generally proceeding from thence in a straight line to the circumference.
For a more full information concerning these and other microscopical objects, the reader may consult Mr Adams's Essays on the Microscope, who has made the most valuable collection that has yet appeared on the subject. See also the articles ANIMALCULE, CRYSTALLIZATION, POLYPE, PLANTS, and WOOD, in the present work.