in a commercial sense, is a society of merchants, mechanics, or other traders, joined together in one common interest. The word is formed of the French *compagnie*, and that of *companie*, or *companier*, which Châtelot observes, are found in the Salique law, tit. 66. and are properly military words, understood of soldiers, who, according to the modern phrase, are comrades or mess-mates, i.e., lodge together, eat together, &c., of the Latin *cum* "with," and *panis* "bread." It may be added, that in some Greek authors, under the western empire, the word *κοινωνία* occurs in the sense of *society*; but it is more probable that the Greeks borrowed it from the French or Italians.

When there are only two or three joined in this manner, it is called a partnership; the term *company* being restrained to societies consisting of a considerable number of members, associated together by a charter obtained from the prince.

The mechanics of all corporations, or towns incorporated, are thus erected into companies, which have charters of privileges and large immunities.

We shall here give some account of the principal companies of merchants, some of which trade with joint stocks, and all of them enjoy by charter many exclusive privileges. For, however injurious these companies may, at this time of day, be reckoned to the nation in general, yet it is certain, that they were the original parents of all our foreign commerce; private traders upon their own bottom being discouraged from hazarding their fortunes in foreign countries, till the methods of traffic had been settled by joint-stock companies: and from this very principle it is, that we find several nations at present endeavouring to extend their trade by the same means. The most ancient trading company, in Britain, is the Hamburgh company, originally called *merchants of the staple*, and afterwards *merchant adventurers*: they were incorporated by king Edward IV., from which time they traded with success till the reign of queen Elizabeth, who, for a farther encouragement of their industry, not only confirmed, but enlarged their privileges. However, it ought to be observed, that this trade is now open to private merchants, upon paying a very small sum to the company. The company of this kind, next

The Eastland company, formerly called merchants of Elbin, were incorporated by queen Elizabeth, and by her greatly encouraged; but, like the former company, it is now become inconsiderable, the trade of Norway and Sweden being laid open by act of parliament.

The Turkey, or Levant company, was likewise incorporated by the same princes, and its charter confirmed and enlarged by king James I., who empowered them to trade to the Levant, or eastern parts of the Mediterranean; particularly to Smyrna, Aleppo, Alexandria, Grand-Cairo, and the other parts of the Turkish dominions. But this trade is now also laid open to private merchants, upon paying a small consideration.

The next in order is the East-India company, first incorporated in the year 1600, and empowered to trade to all countries lying eastward of the cape of Good Hope. Towards the end of king William's reign, an act of parliament passed, granting all private merchants, who should raise a certain sum for the supply of the government, the privilege of trading to these parts. Accordingly, a great many subscribed, and were called the New East-India company; which soon found it necessary to unite with the old one, and trade with one joint stock: since which time, they have been styled the united East-India company; and are at present in a flourishing condition, and in possession of many considerable forts and factories on the coast of Malabar, the Coromandel-coast, the bay of Bengal, &c.

The royal African company was first erected in the year 1661, with an exclusive privilege to trade from cape Blanc, on the coast of Africa, in 20° N. Lat. as far as the cape of Good Hope. But this trade is now laid open by act of parliament.

The Eastland company, the Greenland company, the Hudson's-bay company, the South-sea company, have likewise their several charters and privileges for trading to the places from which they take their denominations.

These are the principal trading companies belonging to the crown of Great Britain; and of a similar nature are the Dutch East and West India companies, the French East and West India companies, &c.

Concerning these companies, it may be proper to remark, that however necessary they might be in the infancy of trade, they are now looked upon by most men in the light of monopolies: hence it is, that their privileges have from time to time been lessened, in order to establish an absolutely free and general trade; and experience hath shewn, that the trade of the nation has advanced in proportion as monopolies have been laid aside. Indeed, to carry on trade with distant countries, where forces and forts are to be maintained, a company with a joint stock seems necessary; or, at least, certain duties ought to be paid by all who trade thither, towards defraying the said expenses: for not to speak of the East-India, Hudson's-bay, &c. companies, the expense of maintaining whole forts must be very considerable, even the Turky, Hamburg, Moicovy, and Eastland companies, which do not trade with a joint stock, are nevertheless obliged to be at considerable charges, in making presents to the grand signior and his ministers, maintaining consuls, &c. It would therefore be injustice that any should trade to the places within their charters, without paying the same duties toward's the company's charge, as the present adventurers pay; but then there appears to be no reason why any of the king's subjects should be barred from trading to those places, or forced to pay a great fine for admission, that are willing to pay the company's duties, and submit to their regulations and orders in other respects.

On the whole, as all restrictions of trade are found to be hurtful, nothing can be more evident than that no company whatsoever, whether they trade in a joint stock, or only under regulation, can be for the public good, except it may be easy for all or any of his majesty's subjects to be admitted into all or any of the said companies, at any time, and for a very inconsiderable fine.

military affairs, a small body of foot, commanded by a captain, who has under him a lieutenant and ensign.

The number of centinels or private soldiers in a company, may be from 50 to 80; and a battalion consists of 13 such companies, one of which is always grenadiers, and posted on the right; next them stand the eldest company, and on the left the second company; the youngest one being always posted in the centre. Companies not incorporated into regiments are called irregulars, or independent companies.

Artillery Company. See Artillery.

Company of Ships, a fleet of merchantmen, who make a charter party among themselves; the principal conditions whereof usually are, that certain vessels shall be acknowledged admiral, vice-admiral, and rear-admiral; that such and such signals shall be observed; that those which bear no guns, shall pay so much per cent. of their cargo; and in case they be attacked, that what damages are sustained, shall be reimbursed by the company in general. In the Mediterranean, such companies are called corsairs.

COMPARATIVE ANATOMY

Is that branch of anatomy which considers the secondary objects, or the bodies of other animals; serving for the more accurate distinctions of several parts, and supplying the defect of human subjects.

It is otherwise called the anatomy of beasts, and sometimes zootomy; and stands in contradiction to human anatomy, or that branch of the art which considers the human body, the primary object of anatomy. See Anatomy.

INTRODUCTION.

The principal advantages of comparative anatomy are the following: first, it furnishes us with a sufficient knowledge of the different parts of animals, to prevent our being imposed upon by those authors who have delineated and described several parts from brutes as belonging to the human body. Secondly, it helps us to understand several passages in the ancient writers in medicine, who have taken many of their descriptions from brutes and reasoned from them. The third and great use we reap from this science, is the light it casts on several functions in the human economy, about which there have been so many disputes among anatomists.

In this view it is altogether needless to insist on those parts whose use is easily understood when once their structure is unravelled; thus for instance, if we be acquainted with the action of the muscles in general, it will not be difficult to determine the use of any particular muscle, whose origin and insertion is known, if we at the same time consider the various connections of the bones to which it is fixed, and the different degree of mobility they have with respect to each other: in the same manner if we know the use of the nerves in general, we can easily assign the use of those nerves which are distributed to any particular part. There is then no occasion for a complete osteology, myology, &c. of the several animals we shall treat of, nor need we trouble ourselves about the structure of any of the parts, unless when it serves to illustrate some of the fore-mentioned purposes.

That the first use we propose from examining the structure of the parts in brutes is real and of consequence, is evident from looking into the works of some of the earliest and greatest masters of anatomy, who for want of human subjects have often borrowed their descriptions from other animals. The great Vesalius, although he justly reproves Galen for this fault, is guilty of the same himself, as is plain from his delineations of the kidneys, uterus, the muscles of the eye and some other parts. Nor is antiquity only to be charged with this, since in Willis's Anatomy Cerebri (the plates of which were revised by that accurate anatomist Dr Lower) there are several of the pictures taken from different brutes, especially the dog, besides those he owns to be such. We shall give several examples of the second use in the sequel of the work.

The animal kingdom, as well as the vegetable, contains the most surprising variety, and the descent in each is so gradual, that the little transitions and deviations are almost imperceptible. The bat and flying squirrel, though quadrupeds, have wings to buoy themselves up in the air. Some birds inhabit the waters, and there are fishes that have wings, and are not strangers to the airy regions; the amphibious animals blend the terrestrial and aquatic together.

As there is then such a vast variety, it is not only needless but impossible to consider all of them particularly. We shall take only some of the most remarkable genera, and hope from what will be said of them, In treating of quadrupeds, we shall divide them into the carnivorous, i.e., those that feed indifferently on animal and vegetable substances, and granivorous; as an instance of these last we shall take the ruminant kind. The fowls we shall also divide into those that feed on grain, and those that feed on flesh. The distinction we shall make in treating of fishes, shall be of those that have lungs, and those that have them not. The first indeed are with difficulty procured, and at the same time differ very little from quadrupeds. As the structure of insects is so very minute, and lends us but little assistance for the ends propoed, we purposely omit them.

In inquiring into the structure of different animals, we ought to be previously acquainted with the form of their body, manner of life, kind of food; or in short, with their natural history, which will lead us to account for the reason of their different structure, and thence explain the actions of the human body.

**Chap. I. Of Quadrupeds in general.**

All quadrupeds have a covering of hair, wool, &c. to defend them from the injuries of the weather, which varies in thickness according to the season of the year, and difference of the climate: thus in Russia and the northern countries, the furs are very thick and warm, while the little Spanish lap-dogs, and Barbary cows, have little or no hair at all.

The cutis and cuticula in quadrupeds, are disposed much in the same way as the human, only more elastic; immediately under this, there is a very thin cutaneous muscular substance called *panniculus carnosus*, which is common to all quadrupeds, the porcine kind excepted; this principally covers the trunk, serving to shrivel the skin, in order to drive off insects, their tails and heads not being sufficient for this purpose, while their extremities are employed in their support and progression.

It has probably been from observing some muscles of the human body, such as the platymina myoides, cremaster, and frontales, and the collapsed tunica cellulosa of emaciated subjects, to resemble this thin muscle, that some of the older anatomists reckoned such a panniculus among the common teguments of the human body. This Carolus Stephanus has well observed.

Most part of quadrupeds want clavicles, whereby their anterior extremities fall upon their chest, so as to make their thorax proportionally narrower than the human. This small distance of their anterior extremities is very necessary for their uniform progression: apes indeed and squirrels have clavicles to allow them a more full use of their extremities in climbing, but when they sit down on all-fours they walk but indifferently.

**Chap. II. The Anatomy of a Dog.**

We may first observe of this animal, as indeed of most quadrupeds, that its legs are much shorter in proportion to its trunk than in man, the length of whose steps depends entirely on the length of his inferior extremities; however, to balance this, the trunk of the animal is proportionally longer and smaller, his spine more flexible, by which he is able at each step to bring his posterior extremities nearer to his anterior. His common teguments are much akin to those of other quadrupeds, only they allow little or no passage for sweat, but when he is over-heated the superfluous matter finds an exit by the labial glands, for he lolls out his tongue and flavors plentifully.

The pyramidal muscles are wanting, to supply which the rectus is inserted fleshly into the os pubis.

The omentum reaches down to the os pubis, which considering the posture of the animal we will find to be a wise provision, since its use is to separate an oily liquor for lubricating the guts and facilitating their peristaltic motion; in our erect posture the natural gravity of the oil will determine it downward, but in the horizontal position of these creatures, if all the intestines were not covered, there would be no favourable derivation of the fluid to the guts lying in the posterior part of the abdomen, which is the highest; and besides, had the omentum reached much farther down in us, we had been in continual hazard of an epiplocele, which the dog is not subject to as his viscera do not press so much on the rings of the abdominal muscles. The inferior and anterior lamella of the omentum is fixed to the spleen, fundus of the stomach, pylorus, liver, &c. in the same way as the human, but the superior having no colon to pass over, goes directly to the back-bone. This serves to explain the formation of the small omentum in the human body, which is nothing but the large omentum, having lost its fat, passing over the stomach and colon, where it reassumes its pinguedo, so proceeds and is firmly attached to the liver, spine, &c. The trice of fat are pretty regularly disposed through it, accompanying the distribution of the blood-vessels to guard them from the pressure of the super-incumbent viscera.

This animal's stomach, though pretty much resembling the human in its shape, is somewhat differently situated. It lies more longitudinal, as indeed all the other viscera do to accommodate themselves to the shape of the cavity in which they are contained, that is, its inferior orifice is much farther down with respect to the superior than the human: by this means the gross food has an easier passage into the duodenum. Again, the fundus of the human stomach, when distended, stands almost directly forwards, which is occasioned by the little omentum tying it so close down to the back-bone, &c. at its two orifices, but it not being fixed in that manner in the dog, the fundus remains always posterior: this also answers very well the shape of the different cavities, the distance between the cardia and fundus being greater than that between the two sides. It seems to be much larger in proportion to the bulk of the animal than the human, that it might contain a greater quantity of food at once, which was very necessary, since this animal cannot at any time get its fulness as men do. The turbilion is not so large, nor is there any coaction forming the antrum Willii, as in the stomach of man. It is considerably thicker and more muscular than ours for breaking the cohesion of their food, which they swallow without sufficient chewing. Hence it is evident the force of the stomach is not so great as some have supposed, nor its contraction so violent; otherwise that of dogs would be undoubtedly wounded by the sharp bones, &c., they always take down; for the contraction here is still greater than in the human stomach, which is much thinner. The rugae of the tunica villosa are neither so large nor situated transversely as in the human, but go from one orifice to the other; the reason of which difference is, perhaps, that they might be in less danger of being hurt by the hard substances this creature frequently feeds upon; and for the same reason there is not the like coaction at their pylorus.

The intestines of this animal are proportionally much shorter than ours; for the food which these creatures mostly use, soon dissolves and then putrefies; on which account there was no occasion for a long tract of intestines, but on the contrary that it should be quickly thrown out of the body: the same is to be observed of all the carnivorous animals. The muscular coat of the intestines is also stronger than the human, to protrude the hard bones, lest they should stop somewhere in the canal.

The valvulae conniventes are less numerous, and in a longitudinal direction.

The duodenum differs considerably in its situation from the human; for in man it first mounts from the pylorus upwards, backwards, and to the right-side, then passes down by the gall-bladder, and marching over the right-kidney and superior part of the psoas muscles, makes a curvature upwards, and passes over the back-bone and vena cava inferior, to the left hypochondrium, where it gets through the omentum, mesentery and mesocolon to commence jejunum, being firmly tied down all the way, the biliary and pancreatic ducts entering at its most depending part; whereas in the dog the duodenum is fixed at the pylorus to the concave surface of the liver, and hangs loose and pendulous with the mesentery backwards into the cavity of the abdomen, then turning up again is fixed to the back-bone, where it ends in the jejunum; the bile and pancreatic juice are poured into it at the most depending part; therefore the same intention seems to have been had in view in the formation of this part in both, viz., the giving the chyle, after the liquors of the liver and pancreas are poured into it, a disadvantageous course, that so it might be the more intimately blended with the humours before its entry into the jejunum, where the lacteals are very numerous: and this by reason of their different posture, the same design (though by a very different order of the parts), is brought about in both.

The other small guts are much the same with ours, only shorter. The great guts are also shorter and less capacious than in the human body; and we take it for a general rule, that all animals that live on vegetable food, have not only their small guts considerably longer, but also their great guts more capacious than such creatures as feed on other animals. Hence man from this form of his intestines and that of the teeth, seems to have been originally designed for feeding on vegetables, and till the most of his food is of that class.

The reason of this difference seems to be, that as animal food is not only much more easily reduced into chyle, but also more prone to putrefaction, too long a remora of the juices might occasion the worst consequences. So it was necessary that their receptacles should not be too capacious, but on the contrary, being short and narrow, might conduce to the reasonable discharge of their contents. Whereas vegetable food being more difficulty dissolved and converted into an animal nature, there was a necessity for such creatures as fed on it to be provided with a long internal canal, that this food in its passage might be considerably retarded, and have time to change its indoles into one more agreeable to our nature. Besides which, there is another advantage which accrues to man in particular, from having his great guts very capacious; for as he is a rational being, and mostly employed in the functions of social life, it would have been very inconvenient, as well as unbecoming for him to be too frequently employed in such ignoble exercises, so that having this large reservoir for his faeces alvine, he can retain them for a considerable time without any trouble.

The appendix veriformis justly enough deserves the name of an intestine cecum in this subject, vermiciform though in the human body it does not, and it has probably been from the largeness of this part in other animals, that the oldest anatomists came to reckon that small appendicule in man as one of the great guts: on its internal surface we observe a great number of mucous glands.

The colon has no longitudinal ligaments, and consequently this gut is not parted up into different bags or cells as the human; nor does this intestine make any circular turn round the abdomen, but passes directly across it to the top of the os sacrum, where it gets the name of rectum.

At the extremity of the intestine rectum or verge of the anus, there are found two bags or pouches which contain a most abominable fetid mucus for which the use is not known, unless it serves to lubricate the strained extremity of the rectum, and defend it against the alperity of the faeces, or to separate some liquor that might otherwise prove hurtful to their bodies. There is nothing analogous to those faeces in the human subject, unless we reckon on the mucilaginous glands that are found most frequent and largest about the lower part of the rectum.

The mesentery is considerably longer than in the human body; for in man had the mesentery been very long, the guts would have fallen down on the stomach, &c., by reason of his erect position. The fat is here disposed in the same way, and for the same reason, as in the omentum. The interstices betwixt the fat are filled with a fine membrane. Instead of a great number of glandulae vagae to be found in the human mesentery, there is only one large gland to be observed in the middle of the mesentery of a dog, which from its imagined resemblance to the pancreas and the name of its discoverers, is called pancreas afelli. The reason why this in man is as it were subdivided into many smaller ones, may possibly be, that as the guts of a human body are proportionally much longer than those of this creature, it would have been inconvenient to have gathered all the lactea primi generis into one place, whereas by collecting a few of these vessels into a neighbouring gland the same effect is procured much more easily.

The pancreas in man lies close to the abdomen, tied down down by the peritoneum; but the capacity of this creature's abdomen not allowing of that situation, it is disposed more longitudinally, being tied to the duodenum which it accompanies for some way. Its duct enters the duodenum about half an inch below the others.

The spleen of this animal differs from ours very much, both in figure and situation. It is much more oblong and thin, and lies more according to the length of the abdomen, like the pancreas. Though the spleen of this creature is not firmly tied to the diaphragm, (which was necessary in our erect posture to hinder it from falling downwards), yet by the animal's prone position, its posterior parts being rather higher than the anterior, it comes to be always contiguous to this muscle, and is as effectually subjected to an alternate pressure from its action as the human spleen is.

The human liver has no fissures or divisions, unless we reckon that small one betwixt the two pylori, where the large vessels enter: whereas in a dog and all other creatures that have a large flexion in their spine, as lions, leopards, cats, &c., the liver and lungs are divided into a great many lobes by deep fissions, reaching the large blood-vessels, which in great motions of the back-bone may easily flounder over one another, and so are in much less danger of being torn or bruised than if they were formed of one entire piece, as we really see it is in horses, cows, and such creatures as have their back-bone stiff and immovable. There is here no ligamentum latum connecting the liver to the diaphragm, which in our situation was necessary to keep the viscus in its place; whereas in this creature it naturally gravitates forwards, and by the horizontal position of the animal is in no danger of prefling against the vena cava: the preventing of which is one use generally affixed to this ligament in man. Had the liver of the dog been thus connected to the diaphragm, the respiration must necessarily have suffered; for as we shall see afterwards, this muscle is here moveable at the centre, as well as at the sides: but in man the liver is fixed to the diaphragm, mostly at its tendinous part; that is, where the pericardium is fixed to it on the other side: so that it is in no danger of impeding the respiration, being suspended by the mediastinum and bones of the thorax. In consequence of this viscus being divided into so many lobes, it follows that the hepatic ducts cannot possibly join into one common trunk till they are quite out of the substance of the liver.

We come next, after having examined the chylopoietic viscera, to discourse of those organs that serve for the secretion and excretion of urine, and first of the kidneys, which in this animal are situated much in the same way as in the human subject, but have no fat on their inferior surface, where they face the abdomen, and are of a more globular form than the human. The reason of these differences will easily appear, if you compare their situation and posture in this animal with those in a man who walks erect. They are placed in this subject in the inferior part of the body, so are not subject to the pressure of the viscera, which seems to be the principal cause of the fatness of those organs in us; and perhaps may likewise be the cause of our being more subject to the stone than other animals. Hence there is no need of any cellular substance to ward off this pressure where there would necessarily be fat collected; but the superior part of their kidneys is pretty well covered with fat, lest they should suffer any compression from the action of the ribs and spine.

In the internal structure there is still a more considerable difference; for the papillae don't here send out single the several tubuli uriniferi, but being all united they hang down in form of a loose pendulous flap in the middle of the pelvis, and form a kind of septum medium; so that a dog has a pelvis formed within the substance of the kidney. The only thing that is properly analogous to a pelvis here, is that sac or dilatation of the ureters formed at the union of the ductula uriniferi. The reason of these particularities may probably be, that the liquors of this animal, as of all those of the carnivorous kind, being much more acid than those that live on vegetable food, its urine must incline much to an alcalicency; as indeed the smell and taste of that liquor in dogs, cats, leopards, &c., evidently shew, being fetid and pungent, and therefore not convenient to be long retained in the body. For this end it was proper, that the secreting organs should have as little impediment as possible by pressure, &c., in performing their functions; and for that design, the mechanism of their kidneys seems to be excellently adapted: we have most elegant pictures in Eustachius of the kidneys of brutes delineated, as such, with a view to shew Vesalius's error in painting and describing them for the human.

The glandule or capulce atrabiliariae, are thicker and rounder than the human, for the same reason as the trabiliariae kidneys.

The ureters are more muscular than the human, because of the favourable passage the urine has through them: they enter the bladder near its fundus.

The bladder of urine differs considerably from the Vesica urinaria; and first in its form, which is pretty much pyramidal or pyriform: this shape of the dog's bladder is likewise common to all quadrupeds, except the ape and those of an erect posture. In men it is by no means pyriform, but has a large sac at its posterior and inferior part: this form depends entirely on the urine gravitating in our erect posture to its bottom, which it will endeavour to protrude; but as it cannot yield before, being contiguous to the os pubis, it will naturally stretch out where there is the least resistance, that is, at the posterior and lateral parts; and were it not for this sac we could not come at the bladder to extract the stone either by the lesser or lateral operation of lithotomy. Most anatomists have delineated this wrong, so that scarce any have judg'd painted it, excepting Mr Cowper in his Myotomia, and Mr Rully.

It has certainly been from observing it in brutes, and young children, that they have been led into this mistake. The same cause, viz., the gravity of the urine, makes the bladder of a different form in brutes; in their horizontal position the cervix, from which the urethra is continued, is higher than its fundus, the urine must therefore distend and dilate the most depending part by its weight.

As to its connection, it is fastened to the abdominal muscles by a process of the peritoneum, and that mem- brane is extended quite over it; whereas in us its superior and posterior parts are only covered by it; hence in man alone the high operation of lithotomy can be performed without hazard of opening the cavity of the abdomen. Had the peritoneum been spread over the bladder in its whole extent, the weight of the viscera in our erect posture would have to bore upon it, that they would not have allowed any considerable quantity of urine to be collected there; but we must have been obliged to discharge its contents too frequently to be consistent with the functions of a social life. Whereas by means of the peritoneum the urine is now collected in sufficient quantity, the viscera not gravitating this way.

It may be taken for a general rule, that those creatures that feed upon animal food have their bladder more muscular and considerably stronger, and less capacious than those that live on vegetables, such as horses, cows, swine, &c., whose bladder of urine is perfectly membranous, and very large. This is wisely adapted to the nature of their food; for in these first, as all their juices are more acid, so in a particular manner their urine becomes exalted, which as its remora might be of very ill consequence must necessarily be quickly expelled. This is chiefly effected by its stimulating this viscus more strongly to contract, and so discharge its contents. That a stimulus is one of the principal causes of the excretion of urine, we learn from the common saline diuretic medicines that are given, which are dissolved into the serum of the blood, and carried down by the kidneys to the bladder: the same appears likewise from the application of cantharides, or without any of these, when the parts are made more sensible, as in an excoriation of the bladder, there is a frequent desire to make water. Accordingly we find these animals evacuate their urine much more frequently than man, or any other creature that lives on vegetable food. And if these creatures, whose fluids have already a tendency to putrefaction, are exposed to heat or hunger, the liquids must for a considerable time undergo the actions of the containing vessels, and frequently perform the course of the circulation without any new supplies of food; by which the fluids becoming more and more acid, the creature is apt to fall into feverish and putrid diseases. These causes have been thought insufficient to produce that fatal and melancholy distemper the rabies canina, vulpina, &c., in such animals; whereas those that feed on vegetable food seldom or never contract these diseases but by infection. That the causes commonly assigned for the rabies canina are insufficient to produce it in dogs and other animals of that kind, is denied in a dissertation on this disease by Dr Heysham. That heat is insufficient, he proves from the disease being totally unknown in South America, where the heat is much greater than in this country. Putrid aliment he also says is taken in great quantity by dogs without any inconvenience; and as it seems in this state to be most agreeable to them, the rabies canina cannot with any probability be ascribed to it. As to want of water, he observes that the disease often originates among dogs that are plentifully supplied with that element, while others long deprived of it have remained perfectly free. In short, Dr Heysham totally denies, not only the efficacy of the caules commonly assigned for the rabies canina, but the nature of the distemper itself; and conjectures that the cause of it is not a putrefaction but an acidity of the fluids. See (the Index subjoined to) MEDICINE.

The spermatic vessels are much the same way disposed as in us; they are contained within the cavity of the abdomen, as the guts are within the peritoneum, which is spread over them, and from which they have a membrane like a meniscus, to hang loose and pendulous in the abdomen; whereas in us they are contained in the cellular part of the peritoneum, which is tensely stretched over them. At their passage out of the lower belly, there appears a plain perforation or hole; and from observing this in quadrupeds has arisen the false notion of hernia or rupture among authors. This opening is of no disadvantage to them, but evidently would have been to us; for, from the weight of our viscera continually gravitating upon these holes, we must have perpetually laboured under enteroceles; thus they are in no hazard of, since in them this passage is at the highest part of their belly, and in their horizontal posture, the viscera cannot bear upon it: and to prevent even the smallest hazard, there is a loose pendulous seminal flap of fat which serves two uses, as it both hinders the intestines from getting into the passage, and also the course of the fluids from being stopped in the vessels, which is secured in us by the cellular substance and tense peritoneum.

The septum medium, or conjunction of the two tunics, is the same as in men. There is next a passage quite down into the cavity, where the testicles lie. Had the same structure obtained in man, by the constant drilling down of the liquor which is secreted for the lubricating of the guts, we should always have laboured under an hydrocele; but their posture secures them from any hazard of this kind: indeed your very fat lap-dogs, who consequently have an overgrown omentum, are sometimes troubled with an epiplocele.

The testes are shorter and not so pendulous as the human, this it has in common with all the dog kind that want the vesiculae seminales, who have it pretty close tucked up, that the seed at each copulation might the sooner be brought from the testes, thus in some measure supplying the place of the vesiculae seminales; for the course of the seed through the vasa deferentia is thus shortened by placing the secreting vessels nearer the excretory organs. This at the same time explains the reason why this creature is so tedious in copulation.

The structure of the testicles is much the same with the human; as are likewise the corpus pyramidale varicoform or pampiniforme, and the epididymis or excretory vessel of the testicle; the vasa deferentia enter the abdomen where the blood vessels come out, and passing along the upper part of the bladder, are inserted a little below the bulbous part of the urethra.

The prepuce has two muscles fixed to it; one that arises from the sphincter ani, and is inserted all along the penis, and this is called retractor preputii, but the other, whose office is directly contrary to this, is cutaneous, and seems to take its origin from the muscles of the abdomen, or rather to be a production of of their tunica carnosa. The corpora cavernosa rise much in the same way as the human; but these soon terminate, and the rest is supplied by a triangular bone, in the inferior part of which there is a groove excavated for lodging the urethra. There are upon the penis two protuberant bulbous fleshy substances, at the back of which are two veins, which by the erectores penis are compressed in the time of coition, and the circulation being stopped, the blood diffuses the large cavernous bodies: after the penis is thus swelled, the vagina, by its contraction, grips it closely, and to the male is kept in action some time contrary to his will; till time be given for bringing a quantity of seed sufficient to impregnate the female; and thus by that orgasmus veneris of the female organs, the want of the vesiculae seminales are in some measure supplied.

But as it would be a very uneasy posture for the dog to support himself solely upon his hinder feet, and for the bitch to support the weight of the dog for so long a time; therefore as soon the bulbous bodies are sufficiently filled, he gets off and turns away from her; had then the penis been pliable as in other animals, the urethra must of necessity have been compressed by this twisting, and consequently the course of the seed intercepted; but this is wisely provided against by the urethra's being formed in the hollow of the bone. After the emission of the seed, the parts turn flaccid, the circulation is restored, and the bulbous parts can be easily extended.

The prostrata seems here divided into two, which are proportionably larger than the human, and afford a greater quantity of that liquid.

The uterus of multifarious animals is little else but a continuation of their vagina, only separated from it by a small ring or valve. From the uterus two long canals mount upon the loins, in which the foetus's are lodged; these are divided into different sacs, which are strongly constricted between each foetus, yet these constrictions give way in the time of birth. From these go out the tubes Fallopian; so that the ovaria come to lodge pretty near the kidneys.

We ought next to examine the structure of the thorax and its contents; but first it may not be amiss to remark of the diaphragm in its natural situation, that it is in general more loose and free than the human, which is owing to its connection with the neighbouring parts in a different manner from ours; the human diaphragm is connected to the pericardium, which again by the intervention of the mediastinum is tied to the sternum, spine, &c., but here there is some distance between the diaphragm and pericardium. We observe further that its middle part is much more moveable, and the tendinous parts not so large. And indeed it was necessary their diaphragm should be somewhat loose, they making more use of it in difficult respiration than man. This we may observe by the strong heaving of the flanks of an horse or dog when out of breath; which corresponds to the rising of the ribs in us.

The disposition and situation of the mammae vary as they bear one or more young. Those of the uniparous kind have them placed between the posterior extremities, which in them is the highest part of their bodies, whereby their young get at them without the inconvenience of kneeling; nevertheless, when the creatures are of no great size, and their breast large, as in sheep, the young ones are to take this posture. In multifarious animals they must have a great number of nipples, that their several young ones may have room at the same time, and these distributed over both thorax and abdomen; and the creatures generally lie down when the young are to be suckled, that they may give them the most favourable situation. From this it does not appear to be from any particular fitness of the vessels at certain places, for giving a proper nourishment to the child, that the breasts are so placed in women, as we find them, but really from that situation being the most convenient, both for mother and infant.

The sternum is very narrow, and consists of a great number of small bones, moveable every way, which always happens in creatures that have a great mobility in their spine. The ribs are freer and by no means so convex as the human, whereby in respiration the motion forward will very little enlarge their thorax, which is compensated by the greater mobility of their diaphragm; so our thorax is principally enlarged according to its breadth and depth, and theirs according to its length. The want of clavicles, and the consequent falling in of the anterior extremities upon the chest, may contribute somewhat to the freer movement of the ribs.

The mediastinum in this creature is pretty broad, whereas the human being so narrow has occasioned a dispute whether there be such a thing or not. The pericardium is not here contiguous to the diaphragm, but there is an inch of distance between them, in which place the small lobe of the lungs lodges, and by this means the liver, &c., of this animal, though continually pressing upon the diaphragm, yet cannot disturb the heart's motion.

The heart is situated with its point almost directly downwards, according to the creature's posture, and is but very little inclined to the left side. Its point is much sharper, and its shape more conoidal than the human. Here the names of right and left ventricles are proper enough, though not so in the human, which ought rather to be called anterior and posterior, or superior and inferior. The animal has the vena cava of a considerable length within the thorax, having near the whole length of the heart to run over ere it gets at the sinus lowerianus dexter. In men, as soon as it pierces the diaphragm, so soon it enters the pericardium, which is firmly attached to it, and immediately gets into the sinus Lowerianus; which sinus in the human subject, by the oblique situation of the heart, is almost contiguous to the diaphragm, and by this we discover that several authors have taken their delineations of the human heart from brutes, which is easily detected by the shape and situation of the heart, and long vena cava within the thorax.

This situation of the heart of the creature agrees best with the shape of its thorax, which is lower than the abdomen.

The ceps of the large blood-vessels from the heart Aorta &c., is somewhat different from the human, for here the condens left subclavian comes off first, and then a large trunk runs some way upwards before it gives off the left carotid. carotid, and splits into the carotid and subclavian of the right side; so that neither here, properly speaking, is there an aorta ascendens, more than in the human; but this name has probably been imposed upon it from observing this in a cow, where indeed there is an ascending and descending aorta.

From this speciality of the distribution of the vessels of the right side, which happens, though not in so great a degree, in the human subject, we may perhaps in some measure account for the general greater strength, readinez or faculty of motion which is observable in the right arm. Upon measuring the sides of the vessels, the surface of the united trunk of the right subclavian and carotid is less than that of the left subclavian and carotid, as they are separated; if so, the resistance to the blood must be less in that common trunk than in the left subclavian and carotid; but if the resistance be smaller, the absolute force with which the blood is sent from the heart being equal, there must necessarily be a greater quantity of blood sent through them in a given time: and as the strength of the muscles is, ceteris paribus, as the quantity of blood sent into them in a given time, those of the right arm will be stronger than those of the left. Now, children being conscious of this superior strength, use the right upon all occasions; and thus from use comes that great difference which is so observable. That this is a sufficient cause seems evident from fact; for what a difference is there between the right and the left arm of one, who has played much at tennis? View but the arms of a blacksmith, and legs of a footman, and you'll soon be convinced of this effect arising from using them. But if by any accident the right arm is kept from action for some time, the other from being used gets the better; and those people are left-handed; for it is not to be imagined that the small odds in the original formation of the vessels should be sufficient to resist the effect of use and habit, (instances of the contrary occur every day); 'tis enough for our present argument, that where no means are used to oppose it, the odds are sufficient to determine the choice in favour of the right. Now because it is natural to begin with the leg corresponding to the hand we have most power of, this is what gives also a superiority to the right leg.

This difference is not peculiar to man, but is still more observable in those creatures, in whom the same mechanism does obtain in a greater degree. Do but observe a dog at a trot, how he bears forwards with his right side; or look at him when scraping up anything, and you will presently see that he uses his right much oftener than he does his left foot. Something analogous to this may be observed in horses.

The thymus of this creature is proportionally much larger than ours, whereas the glandula thyroidea is much less, and it is generally remarked that these two glands do thus always supply the place of each other: that is, in such animals as have a large thymus; the glandula thyroidea is smaller, and vice versa. Hence we are naturally led to ascribe the same use to both, viz.: the separation of a thin lymph for diluting the chyle in the thoracic duct, before it be poured into the blood; then if we consider the different formation of the thorax in both, we shall readily account for the variety in the bulk of these two glands. Respiration being chiefly performed in man by the widening of the chest, the lungs at every inspiration must press upon the thymus, and consequently diminish it; but the diaphragm yielding more in the dog's inspiration, this gland is not so much pressed by the lungs and so will be larger, and hence the glandula thyroidea will be proportionably less; again, from the posture of this creature, we shall see that it was much more convenient for a dog to have the most part of the diluting lymph supplied by the thymus, since the neck being frequently in a descending posture, the lymph of the thyroid gland would have a very disadvantageous course to get to the thoracic duct; whereas in the human body, the thymus is really below the lacteal canal, where it makes its curvature before it opens into the subclavian, and consequently there is a necessity of a considerable share of the diluting liquor being furnished by the thyroid gland, which is situated much higher, so that its lymph has the advantage of a perpendicular descent.

We may here observe that the thoracic duct in a dog has no curvature before it enters the subclavian thoracic vein. The horizontal position of this animal allowing a favourable enough course to the chyle, so as not to need that turn to force its passage into the blood. The lungs of this creature are divided into more numerous lobes and deeper than they are in man, for the same reason as the liver. The left side of the thorax in this animal bears a greater proportion to the right than in man, the one being nearly as three to two, the other as four to three.

We look on it as a general rule, that all quadrupeds, as having occasion to gather their food from the ground, are provided with longer necks than man; but as a long neck not only gives the advantage of too long a lever to the weight of the head, but also when the animal is gathering his food, makes the brain in danger of being oppressed with too great a quantity of blood, by the liquor in these arteries having the advantage of a descent, while that in the veins must remount a considerable way contrary to its own gravity; it was therefore necessary that a part of the length of the neck should be supplied by the length of the jaws. Thus we see horses, cows, &c., who have no occasion for opening their mouths very wide, yet have long jaws. Bull dogs indeed, and such animals as have occasion for very strong jaws, must of necessity have them short; because the longer they are, the resistance to be overcome acts with a longer lever. Another exception to this general rule, is, such animals as are furnished with something analogous to hands to convey their food to their mouths, as cats, apes, &c. The teeth of this creature plainly show it to be of the carnivorous kind, for there are none of them made for grinding their food, but only for tearing and dividing it. Even its posterior teeth are not formed with rough broad surfaces as ours are; but are made considerably sharper, and press over one another when the mouth is shut; that so they may take the firmer hold of whatever comes betwixt them.

The tongue in consequence of the length of the jaws, is much longer than ours; and as this creature feeds with his head in a depending posture, the bolus would... would always be in danger of falling out of the mouth, were it not for several prominences placed mostly at the root of the tongue, and crooked backwards in such a manner as to allow anything to press easily down to the jaws; but to hinder its return. In some animals who feed on living creatures, these under hooks are still more conspicuous; as in several large fishes, where they are almost as large as their teeth in the forepart of their mouth, and near as firm and strong.

When we open the mouth, we see the amygdals very prominent in the posterior part of it; so that it would appear at first view, that these were inconveniently placed, as being continually exposed to injuries from the hard substances this creature swallows; but upon a more narrow scrutiny we find this provided for by two membranous capsules, into which the amygdals, when pressed, can escape and remove themselves from such injuries.

The velum pendulum palati, is in this creature considerably longer than in man, to prevent the food from getting into his nose; which would happen more frequently in this animal than in man, because of its situation while feeding.

In this subject there is no uvula; but then the epiglottis, when pressed down, covers the whole rima entirely, and naturally continues so; there is therefore a ligament, or rather muscle, that comes from the os hyoides and root of the tongue, that is inserted into that part of the epiglottis where it is articulated with the cricoid cartilage, which serves to raise it from the rima, though not so strongly but that it may with a final force be clapped down again. If then in all such animals as have no uvula, the epiglottis is so ordered as to be capable of covering the rima entirely, and if in man the epiglottis cannot be so pressed backwards and downwards, as to shut up the glottis perfectly, but leaves a space that can be exactly filled up by the uvula, we may very reasonably conclude that the use of this part is to supply this deficiency in the epiglottis.

In the upper part of the pharynx, behind the cricoid cartilage, there is a pretty large gland to be found, which serves not only for the separation of a mucous liquor to lubricate the bolus as it passes this way, but also supplies the place of a valve, to hinder the food from regurgitating into the mouth, which it would be apt to do by reason of the descending situation of the creature's head.

The oesophagus is formed pretty much in the same way as the human; authors indeed generally alleged, that quadrupeds have their gullet composed of a double row of spiral fibres decussating one another; but this is proper to ruminating animals, who have occasion for such a decussation of fibres. The action of these may easily be observed in a cow chewing her cud.

The nose is generally longer than in man, and its external passage much narrower. The internal structure is also better adapted for an acute smelling, having a larger convoluted surface on which the membrana Scheideriana is spread, and this is to be observed in most quadrupeds, who have the os spongiosum commonly large, and these too divided into a great number of excessively fine thin lamellae. The elephant, which has a head pretty large in proportion to its body, has the greatest part of it taken up with the cavity of the nose and frontal sinuses, which last extend almost over their whole head, and leaves but a small cavity for their brains. A very nice sense of smelling was not so absolutely necessary for man, who has judgment and experience to direct him in the choice of his food; whereas brutes, who have only their senses, must have these of necessity acute, some having one sense in greater perfection than others, according to their different way of life. We not only conclude a priori from the large expanded membrana Scheideriana that their sense of smelling is very acute, but we find it so by cows, and horses, distinguishing readily between noxious and wholesome herbs, which they do principally by this sense.

The external ear in different quadrupeds is differently framed, but always calculated to the creature's manner of life: in shape it commonly resembles the oblique section of a cone from near the apex to the basis. Hares and such other animals as are daily exposed to insults from beasts of prey, have large ears directed backwards, their eyes warning them of any danger before; rapacious animals, on the other hand, have their ears placed directly forwards, as we see in the lion, cat, &c. The slow hounds and other animals that are designed to hear most distinctly the sounds coming from below, have their ears hanging downwards. Man again, who must equally hear sounds coming from all quarters, but especially such as are sent from about his own height, has his external ear placed in a vertical manner, somewhat turned forward. In short, wherever we see a peculiarity in the make of this organ in any creature, we shall with very little reflection discover this form to be more convenient for that creature than another. There are some differences to be observed in the structure of the internal ear, in different animals; but we know so very little of the use of the particular parts of that organ in the human subject, that it is altogether impossible to assign reasons for these variations in other creatures.

All quadrupeds have at the internal canthus of the Membrana nictitans, a strong firm membrane with a cartilaginous edge, which may be made to cover some part of their eye, and this is greater or less in different animals, as their eyes are more or less exposed to dangers in searching after their food: this membrana nictitans, as it is called, is not very large in this animal; cows and horses have it so large as to cover one half of the eye like a curtain, and at the same time is transparent enough to allow abundance of the rays of light to pass through it; fishes have a cuticle always over their eyes, as they are ever in danger in that inconstant element. In this then we may also observe a sort of gradation.

All quadrupeds have a seventh muscle belonging to Muculus the eye, called fulvus. It surrounds almost the whole optic nerve, and is fixed into the sclerotic coat just as the others are; its use is to sustain the weight of the globe of the eye, and prevent the optic nerve being too much stretched, without obliging the four straight muscles to be in a continual contraction, which would be inconvenient. At the same time this muscle may may be brought to assist any of the other four, by causing one particular portion of it to act at a time.

The next thing to be remarked, is the figure of the pupil, which is different in different animals, but always exactly accommodated to the creature's way of life. Man has it circular for obvious reasons; an ox has it transverse, to take in a larger view of his food; cats again have theirs somewhat perpendicular, (but can alter it pretty much) for a similar reason, and so of the rest; the pupil of different animals varies in wideness according as the internal organs of vision are more or less acute; thus cats and owls who seek their prey in the night, or in dark places (and consequently must have their eyes so formed as that a few rays of light may make a lively impression on the retina) have their pupils in day-time contracted into a very narrow space, as a great number of rays would oppress their nice organs, while in the night they dilate considerably. In the same way when the retina is inflamed, a great number of rays of light would occasion a painful sensation, therefore the pupil is contracted; on the contrary in dying people, or in a beginning amorous it is greatly dilated, as the eyes on such occasions are very difficultly affected, and as it were insensible.

The posterior part of the choroid coat, which is called tapetum, is of different colours in different creatures. Or oxen feeding mostly on grass have this membrane of a green colour, that it may reflect upon the retina all the rays of light which come from objects of that colour, while other rays are obscured; thus the animal sees its food better than other objects. Cats and owls have their tapetum of a whitish colour, and for the same reasons have the pupil very dilatable, and their organs of vision acute; and we shall find that all animals see more or less distinctly in the dark, according as their tapetum approaches nearer to a white or black colour. Thus dogs who have it of a greyish colour distinguish objects better in the night than man, whose tapetum is dark brown, and who we believe sees worst in the dark of any creature; it being originally designed that he should rest from all kinds of employments in the night-time. The difference then of the colour of the tapetum, as indeed the fabric of any other part in different creatures, always depends on some particular advantage accruing to the animal in its peculiar manner of life from this singularity.

We shall now proceed to the brain, which we remark in the first place is proportionally much smaller in all quadrupeds than the human. The reason of which may be, that as those creatures for the most part feed their food with their heads in a depending posture, this situation would make it very inconvenient for the brain itself to send its animal spirits, (or its influence and energy, let that be what it will) through the nerves, so that it was necessary they should be supplied from somewhere else; and consequently there was no reason for the brain itself being of a great bulk. As a confirmation of this theory, we find that the intercostal and eight pair of nerves, which serve the vital organs in the human body, take their origin from the encephalon, which in quadrupeds come mostly from the theca vertebrarum. Again there was no such occasion for so great a quantity of brains in those animals as in man; seeing in them all its energy is employed in their progression, while man has a great waste of spirits in the exercise of his reason and intellectual faculties. And besides all this, a great bulky brain would be inconvenient to these creatures, in so far as it would add considerably to the weight of the head, which having the advantage of a long lever to act with, would require a much greater force to support it, than now it does; for the heads of the greatest part of quadrupeds are not near so heavy as they would at first seem to be, from the sinus frontales being produced a great way upwards to enlarge the organs of smelling.

The pits in the anterior part of their skulls are much more conspicuous than in the human cranium, which may be occasioned by the depending posture of these creatures' heads, while they gather their food: the brain at this time gravitating much on the bones while they are as yet soft, will gradually make impressions upon them at these places where it rises into eminences. This is prevented in man mostly by his erect posture.

The falk is not near so large in quadrupeds as in man, as they have little occasion to be on either side; and the two hemispheres of the brain are in a great measure hindered from jutting against one another in violent motions, by the brain's infusing itself into the above-mentioned pits.

The second process of the dura mater, or tentorium cerebri superexpansum is considerably thicker and stronger in most quadrupeds than in man, especially in such of them as are very swift of foot, as hares and rabbits, and that most when they are old. This membrane is generally ossified, that it may the more effectually keep off the weight of the superincumbent brain from the cerebellum in its rapid motions, which otherwise would be of bad consequence.

The olfactory nerves are very large, and justly deserve the name of processus mammillaris. They are hollow, and consist of a medullary and cineritious substance; and at first sight appear to be anterior ventricles of the brain produced; but in man they are small, and without any discernible cavity. The reason of this is pretty evident, if we consider how this animal's head is situated; for the lymph continually gravitating upon the inferior part of the ventricles may thus elongate and produce them: but from this very inferior part the olfactory nerves rise, and are sent immediately through the os ethmoides into the nose. Hence the ancients thinking they were continued hollow into the nose, believed they were the emunctories of the brain. In the brain of sheep, which by its firm texture is the best subject of any for searching into the structure of this part, we evidently see, that the name of the sigmoid cavities was very properly applied by the ancients to the lateral ventricles of the brain, which are really of a greater extent than they are ordinarily painted by the anatomists, reaching farther backwards and forwards again under the substance of the brain.

The nates and testes deserve this name much better here than in the human body with respect to each other. They are here also of different colours, the nates being of the colour of the cortical, and the testes of the medullary substance of the brain: whereas in man they are both of one colour. The reason of these differences, differences, and others of the like nature to be met with, we shall not pretend to determine; for we have hitherto such an imperfect knowledge of the brain itself, that we are entirely ignorant of the various uses of its different parts; we may in general conclude, that the varying in one animal, from what it is in another, is fitted to the creature's particular way of living.

The rete mirabile Galeni, situated on each side of the sella turcica, about which there has been so much dispute, is more remarkable in quadrupeds than in the human subject, though it is certainly to be found there too; notwithstanding several anatomists have denied its existence. The use indeed which Galen attributes to it is frivolous, and not well grounded; for he will have this plexus of vessels serve for checking the impetuosity of the blood in the brain; but it is evident this cannot be the use of it: if indeed the whole carotid artery had split into such small vessels as compose this network, the motion of the blood would certainly have been retarded in it; but this is not the case, for it only sends off a few small twigs to compose the plexus at its entry into the cranium; and the branches going out from this same plexus, are distributed to the neighbouring nerves: among the rest it gives some twigs to the ophthalmic branch of the fifth pair. It is this distribution of these arteries makes it so difficult to determine whether there is a communication between the intercostal and that nerve; for if you dissect the parts in a recent subject, you would at first view affirm, that there is an anastomosis; but when the carotid artery is injected, and the plexus filled with the tubile liquor, these branches, which formerly seemed to be nerves, have now the appearance of arteries by the vessels of their coats being injected.

The structure of the brain differing but very little in all quadrupeds, it will be needless to examine it in any other.

**Chap. III. The Anatomy of a Cow.**

The next species of quadrupeds we proposed to consider was the ruminant kind, of which we have an example in a cow; and accordingly shall take the fetus of the animal in utero, that we may first remark some things that are peculiar to it in that state, and afterwards proceed to examine its viscera as a ruminant animal; first then as a fetus.

The form of a cow's uterus differs from the human, in having two pretty large cornua. This is common to it with other brutes; for a bitch has two long cornua uteri; but these again differ (as being multiparous and uniparous) in this, that in the bitch's cornua the foci are contained, whereas here there is only part of the secundines, being mostly the allantois with the included liquor. The muscular fibres of the uterus are more easily discovered; its internal surface has a great number of spongy, oblong, protuberant, glandular bodies fixed to it by a fine membrane: these are composed of the several large vessels of the uterus terminating here. These are very small, and sometimes not to be observed at all. In an impregnated uterus, we can easily press out of them a chylous mucilaginous liquor; they are composed of a great many processes or digituli, and deep caverns answering to as many processes and caverns of the placenta. Their resemblance has occasioned the name of Papilla to be given them; and hence it was that Hippocrates was induced to believe, that the fetus sucked in utero. It is not easy to determine, whether the uterus grows thicker or thinner in the time of gestation. The membranes it is plain (by the stretching of the parts) must be made thinner; but then it is as evident, that the vessels are at that time enlarged, upon which principally the thickness of any part depends; so there seems to be as much gained the one way, as lost the other. The os uteri is entirely shut up by a glutinous mucilaginous substance, that is common to the females of all creatures when with young; by this the external air is excluded, which would soon make the liquors corrupt, it also prevents the inflammation of the membranes, and the hazard of abortion. By this means also the lips of the womb are kept from growing together, which otherwise they would certainly at this time do. There are mucous glands placed here to screen this gluten, which on the breaking of the membranes with the contained waters make a sap that lubricates and waxes the parts, and makes them easily yield. The first of the proper involucra of the fetus is the chorion.

The chorion is a pretty strong firm membrane, on whose external surface are dispersed a great many red flecky bodies of the same number, size and structure with the papillae, with which they are mutually indented. They have been called Cotyledones from cotyledon cavity. This is greatly disputed by some as a name very improper, but without reason, since the surface that is connected to the papillae is concave, though when separated it appears rather convex. To shun all dispute, they may be called properly enough Placentulae, since they serve the same use as the placenta in women. The separation of these from the papillae without any dilaceration seems to prove beyond a reply, that there can be here no anastomoses betwixt the vessels; on their coats run a great number of vessels, that are sent to the several placentulae, on the external side next to the uterus; whereas in creatures that have but one placenta, as in the human subject, cats, dogs, &c., the adhesion is somewhat firmer: the placenta are likewise joined to the papillae in the cornua uteri. We shall next give the history of the allantois.

This is a fine transparent membrane contiguous to Allantois the former. It is not a general involucrum of the fetus in the mother; for it covers only a small part of the amnios: it is mostly lodged in the cornua uteri. In mares, bitches and cats, it surrounds the amnios, being everywhere interposed betwixt it and the chorion. In sheep and goats it is the same as in this animal; and in swine and rabbits it covers still less of the amnios. This sac is probably formed by the dilation of the urachus, which is connected at its other end to the fundus of the bladder, through which it receives its contents; and the membrane is doubled at the extremity of the canal to hinder the return of the urine back into the bladder. Its vessels are excessively fine and few, and we cannot force an injected liquor farther than the beginning of this coat. This membrane is so far analogous to the cuticle, as not to be liable to corruption, or easily irritated by acid liquors. The existence of this membrane in women has has been very warmly disputed on both sides: those who are against its existence deny they could ever find it, and allowing it were so, allege, that since the urachus is impervious, as appears by our not being able to throw liquids from the bladder into it, or vice versa, it cannot serve the use, that is agreed by all it does serve in beasts, and therefore in the human body there is no such thing; but if we consider on the other hand, that first there seems to be the same necessity for such a reservoir in man, as in other animals. Secondly, That we actually find urine contained in the bladder of the human fetus. Thirdly, That urine has been evacuated at the navel when the urethra was flopped, which urine without this conduit would have fallen into the cavity of the abdomen. Fourthly, That midwives do generally remark two different sorts of waters come away at the time of birth; and lastly, That Dr Littré and Dr Hale have given in this membrane of an human subject, with all the other peculiarities curiously prepared, the one to the Royal Academy at Paris, the other to the Royal Society at London, by which societies their respective accounts are attested; not to mention Verheyen, Heifter, Keil, &c. who affirm their having seen it; and Mr Albinius, that famous anatomist, professor at Leyden, is said to have shewn to his college every year a preparation of it. On all these accounts, it seems most probable, that there is such a membrane in the human body.

The third proper integument of the fetus is the amnios; it is thinner and firmer than the chorion; it has numerous ramifications of the umbilical vessels spread upon it, the lateral branches of which separate a liquor into its cavity. This is the proper liquor of the amnios, which at first is in a small quantity, afterwards increases for some months, then again decreases; and in a cow near her time, the quantity of this liquor is not above a pound. This membrane does not enter the cornua uteri in this creature.

There are here two venæ umbilicales, and but one in the human subject; because the extreme branches coming from the several placentulae could not unite, so soon, as they would have done, had they come all from one cake as in the human.

There is a small round fleshy body that swims in the urine of this creature, mares, &c. called cuticula, which is the hypomenes of the ancients. Several idle opinions and whims have been entertained as to its use; but that seems to be still unknown, or how it is generated or nourished; for it has no connection with the fetus or placentulae.

Having thus considered the several involucra of this animal in a fetus state, let us next observe the specialities in its internal structure peculiar to a fetus.

The umbilical vein joins the vena portarum in the caput glissonianum without sending off any branches as it does in the human subject. This vein soon after birth turns to a ligament, yet there are some instances where it has remained pervious for several years after birth, and occasioned an hemorrhage. We may next observe the duct called canalis venosus, going straight from the caput glissonianum to the vena cava; this turns also afterwards to a ligament. The umbilical arteries rise at acute angles from the internal iliacs, whatever some may say to the contrary: these also become impervious.

The pulmonary artery coming from the right ventricle of the heart divides into two, the smallest called canalis arteriosus opens into the descending aorta; the other divides into two, to serve the lung on each side. The foramen ovale is placed in the partition between the right and left auricles. At the edge of this hole ovale, is fixed a membrane, which when much stretched will cover it all over, but more easily yields to a force that acts from the right auricle to the left, than from the left to the right. After what has been said, we may easily understand how the circulation is performed in a fetus. The blood being brought from the placenta of the mother, is thrown into the caput glissonianum, from where it is intimately blended with the blood in the vena portarum: then part of this blood goes directly into the vena cava by the ductus venosus, the rest passes through the liver. First then the whole is sent from the vena cava into the right auricle, from whence part of it is sent by the foramen ovale into the left auricle; the rest passes into the right ventricle; then into the pulmonary artery; then the greatest share it receives is sent immediately into the descending aorta by the canalis arteriosus; and the remainder circulates through the lungs, and is sent back by the pulmonary veins into the left auricle; which, with the blood brought there by the foramen ovale is sent into the left ventricle, from whence it is driven by the aorta through the body. The great design of this mechanism is, that the whole mass of blood might not pass through the collapsed lungs of the fetus, but that part of it might pass through the foramen ovale and canalis arteriosus without circulating at all through the lungs.

This was the opinion that universally prevailed till Messrs Mery and Winiford examined their opinions of this subject. Mr Winiford endeavours to reconcile these two opinions, by saying the blood may pass either way, and that it is here as it were blended; his reason is, that on putting the heart in water, the foramen ovale transmits it any way. Mr Rohault, professor of anatomy at Turin, and formerly one of Mery's scholars, strongly defends his matter and criticizes Mr Winiford. What he principally builds on is the appearance this foramen has in some dried preparations: this Mr Winiford won't allow as a proof. After all, the common opinion seems most probable; and that for the following reasons: first the pulmonary artery being larger signifies nothing, since its coats are not only thinner, and will be more easily distended, but also the resistance to the blood in the pulmonary artery from the collapsed lungs is greater than the resistance to the blood in the aorta. Secondly, if we should allow any of these two uncommon opinions, we should have the right ventricle vastly more capacious than the left; for if we suppose the foramen ovale to be capable of transmitting one half of the whole mass of blood in any given time, and the arteriosus as much in the same time; then, according to Mr Mery's opinion, the whole mass of blood being driven from the right ventricle into the pulmonary artery, one third passes by the canalis arteriosus into the descending aorta; two thirds passing through the lungs and returning into the left auricle, one half of it, or one third of the whole mass passes by the foramen ovale into the right auricle, and the other or the last third will be sent into the left ventricle, and thence expelled into the aorta; which third, with that from the pulmonary artery by the canalis arteriosus, circulating through the body, are returned into the right auricle, where meeting with the other third from the foramen ovale, with it are sent into the right ventricle to undergo the same course. Thus the whole mass is expelled by the right ventricle, and only one third by the left. If this was the case, why is not the right ventricle three times as large and strong as the left? Then, if according to Mr Winiford's system, the foramen ovale transmits equal quantities from both auricles, this comes to the same, as if there was no foramen ovale at all; that is to say, the whole mass going from the right auricle into the right ventricle and pulmonary artery, one third of the whole mass passes into the aorta through the canalis arteriosus, the other two thirds passing through the lungs, return to the left ventricle and auricle, to be sent through the canalis arteriosus to the right ventricle to undergo the same fate; thus the right ventricle expels the whole mass, the left only one third; but if according to the common opinion we suppose the foramen ovale to convey the blood from the right to the left auricle; then one third passes this way into the left ventricle, the other two thirds are sent by the right ventricle into the pulmonary artery, from whence one third passes by the canalis arteriosus into the aorta descendens, the other third circulates through the lungs and is returned into the left ventricle, where meeting with that from the foramen ovale, is with it expelled into the aorta; and with the one third transmitted by the canalis arteriosus returns into the auricle to run the same race as before. Thus we conclude that two-thirds are expelled by each ventricle, and the whole circulates through the body; and hence they come to be of pretty equal dimensions. In all this calculation we have had no regard to the blood discharged from the umbilical vessels; but the greater quantity returned by the veins than sent out by the arteries still argues for the common opinion.

The kidneys in the fetus are composed of different lobes, which serves to give us an idea of the kidneys being a congeries of different glands; these lobes being kept contiguous by the external membrane are pressed by the other viscera till at length they unite.

We come now to consider the creature as a ruminant animal. There are no dentes incisores in the upper jaw, but the gums are pretty hard, their tongue rough; and they supply this defect by wrapping their tongue round a tuft of grass, so pressing it against the upper-jaw keep it stretched, and cut it with the teeth of the under-jaw; then, without chewing, throw it down into the oesophagus, which in these creatures consists of a double row of spiral fibres decussating one another. All animals which ruminate must have more ventricles than one; some have two, some three; our present subject has no less than four. The food is carried directly down into the first, which lies upon stomachs, the left-side and is the largest of all; it is called ventriculus, and xiphias by way of eminence. It is what is called by the general name of paunch by the names and vulgar. There are no rugae upon its internal surface; the food, by the force of its muscular coat, and the liquors poured in here, is sufficiently macerated, after which it is forced up hence by the oesophagus into the mouth, and there it is made very small by mastication; this is what is properly called chewing the cud, or rumination; after this it is sent down by the gullet into the second, for the oesophagus opens indifferently into both; however the creature has a power to direct it into which it will. Some tell us that the drink goes into the second; but that might be easily determined by making them drink before slaughter; the second stomach, which is the anterior and smallest, is called reticulum, the hornet or king's hood. It consists of a great number of cells on its internal surface of a regular pentagonal figure, like a honeycomb. Here the food is farther macerated, from which it is protruded into the third, called omasum or omastum, wedge the manyplies; because the internal surface rises up into a great many pieces or folds, and stratum super stratum, according to the length of this stomach. Some of these pieces are further produced into the stomach than others, i.e., first two long ones on each side, and within these, two shorter in the middle, &c. There are several glands in this stomach which is next to the xiphias in bigness, and from this it passes into the fourth, whose names are abomasum, abomasum, caillie, or the red, which is the name it commonly has because of its colour. Caillie signifies curdled; and hence the French have given that as a name to this fourth stomach; because any milk that is taken down by young calves from the long remora it makes here, turns acid; and by the remains of the milk before taken down, afflicting, it is curdled. It is this fourth stomach with the milk curdled in it, that is commonly taken for earning of milk; (as they call it), but after the bile and pancreatic juice enter, this coagulation is not to be found, which shows the use of these liquors. There are other creatures that use the same food, that have not such a mechanism in their digestive organs; horses also, &c., have but one stomach where grass is macerated, and a liquor for their nourishment extracted, and the remainder sent out by the anus very little altered. From this different structure of the stomach in these creatures, a ruminant animal will be served with one third less food than another of equal bulk; graziers are sufficiently acquainted with this. The reason is, that ruminating animals have many and strong digestive organs; all their food is fully prepared and almost converted into chyle; but a horse's stomach is not fitted for this, so that they require a much greater quantity of food to extract the same nourishment.

The guts of these creatures are of a considerable length in proportion to the bulk of the animal's body; and this confirms what we said formerly on the subject of the intestines of a dog, viz., that the length and capacity of the guts were different in different animals according to the nature of their food. The duodenum is formed here much the same way as in a dog, and the general intention kept in view, with regard to the mixture of the bile and pancreatic lymph. The great guts here hardly deserve that name, their diameter differing very little from that of the small ones; but to compensate this, they are much longer proportionally than a dog's are, being convoluted in the same way as the small guts are. The cæcum is very large.

The spleen differs not much either in figure or situation from that of a dog's; but it is a little more firmly fixed to the diaphragm, there not being here so much danger of this viscus being hurt in the flexions of the spine.

The liver is not split into so many lobes in this creature as either in a man or dog, which depends on the small motion this creature enjoys in its spine, which made such a division needless.

Their vesica urinaria is of a pyramidal shape, and has scarce any muscular fibres. It is very large and membranaceous; for the urine of these creatures not being so acid as that of carnivorous animals, there was no such occasion for expelling it so soon.

This creature is provided with a loose pendulous scrotum, and consequently with vesiculae feminales. The female organs differ from those of a bitch, mostly as to the form of the cornua uteri, which are here converted in form of a snail. In this and all uniparous animals they contain only part of the fecundines; but in bitches and other multiparous animals they run straight up in the abdomen, and contain the fetus themselves.

The situation of the heart is pretty much the same with that of a dog, only its point is rather sharper; in us the heart beating continually against the ribs, and both ventricles going equally far down to the constitution of the apex it is very obtuse; but here the apex is made up only of the left ventricle, so is more acute.

The aorta in this creature is justly divided into ascending and descending, though this division is ill founded either in a dog or man; and it has certainly been from this subject that the older anatomists took

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Dr Hunter hath lately made some curious discoveries relative to these internal receptacles of air in the bodies of birds. Some of them are lodged in the fleshy parts, and some in the hollow bones; but all of them communicate with the lungs. He informs us, that the air-cells which are found in the soft parts have no communication with the cellular membrane which is common to birds as well as other animals. Some of them communicate immediately with each other, but all of them by the intervention of the lungs as a common centre. Some of them are placed in cavities, as the abdomen; others in the interstices of parts, as about the breast. The bones which receive air are of two kinds; some of them divided into innumerable cells; others hollowed out into one large canal. They may be distinguished from such as do not receive air by having less specific gravity; by being less vascular; by containing little oil; by having no marrow nor blood in their cells; by having less hardness and firmness than others; and by the passage for the air being perceivable.

The mechanism by which the lungs are fitted for conveying air to these cavities is, their being attached to the diaphragm, and connected also to the ribs and sides of the vertebrae. The diaphragm is perforated in several places by pretty large holes, allowing a free passage of air into the abdomen. To each of these holes is attached a distinct membranous bag, thin and transparent. The lungs open at their anterior part into membranous cells, which lie upon the sides of the pericardium, and communicate with the cells of the sternum. The superior parts of the lungs open into cells of a loose net work, through which the trachea and oesophagus pass. When these cells are distended with air, it indicates passion, as in the case of the turkey-cock, pouting-pigeon, &c.

These cells communicate with others in the axilla, and under the large pectoral muscle; and those with the cavity of the os humeri, by means of small openings in the hollow surface near the head of that bone. Lastly, The posterior edges of the lungs have openings into the cells of the vertebrae, ribs, os sacrum, and other bones of the pelvis, from which the air finds a passage to the cavity of the thigh-bone.

Concerning the use of these cavities the doctor conjectures, that they are a kind of appendage to the lungs; and that like the bags continued through the bellies of amphibious animals, they serve as a kind of reservoirs of air. They assist birds during their flight, which must be apt to render frequent respiration difficult. He farther infers, that this construction of the organs of respiration may assist birds in singing; which, he thinks may be inferred from the long continuance of song between the breathings of a canary bird. On tying the trachea of a cock, the animal breathed through a canula introduced into his belly; another through the os humeri, when cut across; and a hawk through the os femoris. In all these cases the animals soon died. In the first, the doctor ascribes the death to an inflammation of the bowels; but in the last, he owns it was owing to difficult breathing. What took place, however, was sufficient to show that the animals really did breathe through the bone. their abdomen with air, and expanding their tail, they come to make the posterior part of their bodies considerably higher; and thus they fly with their bodies near in an horizontal situation. Hence we find, that if their necks are kept from being stretched out, or if you cut away their tails, they become incapable of flying any considerable way. The largeness of the wings in different fowls varies, according to the occasions of the creature. Thus birds of prey, who must fly a considerable way to provide their food, have large strong wings; whereas domestic birds, who find their nourishment almost everywhere, have very short and but small wings. The best account of the manner of progression of fowls, is given by Alfonso Borellus in his treatise De motu animalium; and in the "Religious Philosopher" we have Borelli's doctrine stript pretty much of its mathematical form. The posterior extremities are so situated as to make us at first think they would be in continual hazard of falling down forwards when they walk; but this is prevented by their holding up their heads and necks; and when they have occasion for climbing up a steep place, they stretch out their head and necks forwards. Thus we may observe a goose, entering a barn-door, where generally there is an ascending step, to stretch out its neck, which before was raised, and incline its body forwards; this is laughed at by the common people, who ascribe it to a piece of folly in the goose, as if afraid of knocking its head against the top of the door.

Carnivorous animals are provided with strong crooked claws for the catching their prey; water-fowls use them for swimming; and principally for this purpose have a strong firm membrane interposed betwixt the toes. There is a beautiful mechanism to be observed in the toes of fowls, which is of considerable use to them; for their toes are naturally drawn together or bended when the foot is bended; this perhaps proceeds from the tendons of the toes passing over in them what is analogous to our heels, and when the foot is bended must consequently be much stretched; and since they are inserted into the toes, must of necessity bend them when the foot is bended; and when the foot is extended, the flexors of the toes are again relaxed, and they therefore expanded. This is of great use to water-fowls; for had there been no such contrivance as this, they must have lost as much time when they pulled their legs in, as they had gained by the former stroke; but as the parts are now framed, whenever the creature draws in its foot, the toes are at the same time bended and contracted into less space; so that the resistance made against the water is not near so great as before; on the contrary, when they stretch their feet their toes are extended, the membrane betwixt them expanded, and consequently a greater resistance made to the water. Again, such fowls as live mostly in the air, or have occasion to sustain themselves on branches of trees in windy weather, and even in the night-time when asleep, while all their muscles are supposed to be in a state of relaxation; such have no more to do but lean down the weight of their bodies, and their toes continue bended without any muscles being in action; and whenever they would disentangle themselves, they raise up their bodies, by which their feet, and consequently their toes, are extended.

Carnivorous fowls have their beaks long, sharp and crooked; the domestic fowls, such as the hen kind, &c. have strong short beaks, commodiously fitted to dig up and break their food; the water-fowls again have long or very broad scoop-like beaks, which is most convenient for them. The sternum of fowls is much larger proportionally than the human, and has a ridge rising in its middle for the more commodious origin of the muscles that move the wings. It is also less moveable than ours; for had it been very moveable, a great deal of the force employed for moving the wings would at every contraction of the muscles have been lost, or else some other muscles must have come in play to keep firm the sternum; but this additional weight would have been inconvenient for their progression.

What other things are most remarkable in the structure of the several vifera, we shall consider in that common domestic animal, the cock or hen, and afterwards observe the difference of their vifera chylopoietica from a carnivorous fowl.

CHAP. V. The Anatomy of a Cock.

The oesophagus of this creature runs down its neck somewhat inclined to the right-side, and terminates in a pretty large membranous sac, which is the ingluvies or crop where the food is macerated and dissolved by a liquor, separated by the glands which are easily observed everywhere on the external surface of this bag. The effect of this maceration may be very well observed in pigeons, who are sometimes in danger of being suffocated by the peafe, &c. they feed upon, swelling to such an immense bulk in their ingluvies, that they can neither get upwards nor downwards. If it be a favourite fowl, it might be preserved by opening the sac, taking out the peafe and sewing up the wound.

The food getting out of this sac, goes down by the ventriculus remaining part of the oesophagus into the ventriculus succenturiatus or infundibulum peyeri, which is a continuation of the gullet with more numerous glands, which separate a liquor to dilute the food still more, which at length gets into the true stomach or gizzard, which consists of two very strong muscles covered externally with a tendonous aponeurosis, and lined on the inside by a very thick firm membrane, which we evidently discover to be a production of the cuticle. This might have been proved in some measure a priori, from taking notice that this membrane, which in chicks is only a thin slight pellicle, by degrees turns thicker and stronger, the more attrition it suffers; but there is no other animal substance, so far as we know, which grows more hard and thick by being subjected to attrition, excepting the cuticle. Hence may be drawn some kind of proof of what hath been affirmed concerning the tunica villosa of the stomach, and intestines in the human body, viz. that it was only a continuation of epidermis. Nay, all the hollow parts of the body, even arteries, veins, &c. seem to be lined with a production of this membrane or one analogous to it. The use of this internal coat of the stomach of fowls is to defend the more tender parts of that viscera from from the hard grains and little stones those creatures take down.

The digestion of these animals is performed, partly at least, by attrition, as is evinced by many experiments. We see them daily take down considerable numbers of the most solid rugged little flints they find, and these can serve for no other purpose than to help the trituration of their aliment. After these pebbles by becoming smooth are unfit for this office, they are thrown up by the mouth; hence fowls that are long confined, though never so well fed, turn lean for want of these stones to help their digestion; but this was put beyond all dispute by Mr. Tavernier, who gave a species of metal to an ostrich, convex on one side, and concave on the other, but carved on both; and opening the creature's body some time after, it was found that the carving on the convex side was all obliterated, while the engraved character remained the same as before on the concave side which was not subjected to the stomach's pressure; which could not have happened had digestion been performed by a menstruum, or any other way whatsoever; but may be easily solved by allowing a simple mechanical pressure to take place.

**Duodenum.**

The duodenum begins pretty near the same place, at which the oesophagus enters; yet notwithstanding the vicinity of these two tubes, the aliment are in no danger of getting out before they are perfectly digested, by reason of a protuberance or septum medium between the orifices; and in those creatures who have such a strong muscular stomach, it is a matter of great indifference, whether the entry of the oesophagus or pylorus be highest, provided that the entry of the oesophagus does not allow the food to regurgitate, since the force of the stomach can easily protrude it towards the duodenum. This gut is mostly in the right side, and hangs pendulous in their abdomen, having its two extremities fixed to the liver. The ductus communis choledochus enters near its termination, where it mounts up again to be fixed to the liver; and left, by the contraction of the intestine, the bile should pass over without being intimately blended with the chyle, that duct enters downwards contrary to the course of the food, and contrary to what is observed in any of the animals we have mentioned yet. But still the general intention is kept in view, in allowing these juices the fairest chance of being intimately blended with the food.

The small guts are proportionally larger than those of carnivorous birds, for the general cause already assigned. At the end of the ilium they have two large intestina ceca, one on each side, which serve as reservoirs to the feces; which after some remora there regurgitate into what soon becomes the rectum, which, together with the excretories of urine, and organs of generation, empties itself into the common cloaca.

The small intestines are connected by a long loose mesentery, which has little or no fat accompanying the blood vessels, there being no hazard of the blood's being stopped. There are no lacteal vessels, glandular veins or pancreas affilii to be observed here. The mefereae veins are proportionally very large, if you either compare them with the corresponding arteries, or consider them with respect to the guts themselves.

The want of lacteals, &c., is supplied by these veins. As a proof of these having a communication with the lacteal vessels, in larger fowls the guts can be distended by flesh, how blowing in at the mefereae vein; and from this difference of structure, the use of the glandula vagae, &c., can easily be assigned, viz., the chyle in these animals, that have lacteals, being to be mixed with the blood therein in a considerable quantity at a time, left its particles other animals should attract one another too strongly, and so hinder this mixture; it was therefore necessary it should be well diluted by the humores inquinii, which bear a very great proportion to the quantity of pure chyle; since the lymph from the inferior extremities, abdominal viscera, neck, &c., are poured into it. Here there was no hazard of any such inconvenience by the chyle being mixed with the blood in small proportion from the immense number of the small extremities of the mefereae veins.

The pancreas in the creature lies betwixt the two pancreatic folds of the duodenum, and sends two or three ducts into this gut pretty near the biliary.

The spleen is here of a round globular figure, situated between the liver and stomach, and betwixt these and the back-bone it enjoys the same properties as in other animals, viz., large blood-vessels, &c. All its blood is sent into the vena portarum, and has a perpetual conglutination. It has no excretory as far as we know. Their liver is divided into two equal lobes by a pellucid membrane, running according to the length of their body; and hence we may observe, that it is not proper to that bowel to lie on the right-side, which is still more confirmed by what we observe in fishes, where it almost lies in the left-side.

The shape of their gall-bladder is not much different from that of quadrupeds, but is thought to be longer in proportion to the size of the animal, and is farther removed from the liver; though in fishes it is still further removed, not being at all contiguous; and in them the ductus hepaticus and cysticus do not unite till just at the entry into the gut. In these animals, viz., fishes, there seems to be no way of the bile getting into the gall-bladder but by regurgitation.

The principal difference to be remarked in their heart, is the want of the valvula tricupidedes, and their place being supplied by one fleety flap.

The lungs are not loofe within the cavity of the Pulmones thorax, but fixed to the bone all the way; neither their structure are they divided into lobes, as in those animals that have a large motion in their spine. They are two red spongy bodies covered with a membrane that is pervious, and communicates with the large vesicles or air bags that are dispersed over their whole abdomen, which vesicles serve two very considerable uses; the one is to render their bodies specifically light, when they have a mind to ascend and buoy themselves up when flying, by diffusing their lungs with air, and also straighten their trachea arteria and to return the air.

Secondly, they supply the place of a muscular diaphragm and strong abdominal muscles; producing the same effects on the several contained viscera, as these muscles would have done without the inconvenience of their additional weight; and conducing as much to the exclusion of the egg and feces.

The trachea arteria, near where it divides, is very Trachea much much contracted, and their voice is principally owing to this coarction. If you listen attentively to a cock crowing, you will be sensible that the noise does not proceed from their throat, but deeper; nay this very pipe, when taken out of their body and cut off a little, after its division, and blown into, will make a squeaking noise, something like the voice of these creatures. On each side, a little higher than this contraction, there is a muscle arising from their sternum, which dilates the trachea. The cartilages of which the pipe is composed in this animal, go quite round it; whereas in men and quadrupeds, they are discontinued for about one-fourth on the back-part, and the intermediate space filled up by a membrane. Neither is the trachea so firmly attached to their vertebrae as in the other creatures we have examined. This structure we shall find of great service to them, if we consider, that had the same structure obtained in them as in us, their breath would have been in hazard of being stopped at every flexion or twisting of their neck, which they are frequently obliged to. This we may be sensible of by bending our necks considerably on one side, upon which we shall find a great straitness and difficulty of breathing; whereas their trachea is better fitted for following the flexions of the neck by its loose connection to the vertebrae: and as from the structure of the trachea it cannot yield to every cause distending the oesophagus as in us, it was proper they should be placed at a greater distance from each other, which we accordingly find they are.

In place of a muscular diaphragm, this creature has nothing but a thin membrane connected to the pericardium, which separates the thorax and abdomen. But besides this, the whole abdomen and thorax are divided by a longitudinal membrane or mediastinum connected to the lungs, pericardium, liver, stomach, and to the fat lying over their stomach and guts, which is analogous to an omentum, and supplies its place.

The kidneys lie in the hollow, excavated in the side of the back-bone, from which there is sent out a blueish coloured canal, running along by the side of the vas deferens, and terminates directly into the common cloaca. This is the ureter, which opens by a peculiar aperture of its own, and not at the penis. This creature having no vesica urinaria, it was thought by some they never passed any urine, but that it went to the nourishment of the feathers, but this is false; for that whitish substance that you see their greenish faeces covered with, and which turns afterwards chalky, is their urine. Let us next consider the organs of generation of both sexes, and first those of the male.

The testicles are situated one on each side of the back-bone, and are proportionally very large, to the creature's bulk. From these run out the vasa seminiferi, at first straight, but after they recede farther from the body of the testicle, they acquire an undulated or convoluted form, as the epididymis in man. These convolutions partly supply the want of vesicule seminales, their coition being at the same time very short; these terminate in the penis, of which this creature has two, one on each side of the common cloaca pointing directly outwards, and are very small and very short, hardly so big as a millet seed; whence they have escaped the notice of anatomists, who have often denied their existence. This is what is chiefly remarkable in the organs of the male.

The racemus vitellorum being analogous to the ovaria in the human subject, are attached by a proper membrane to the back-bone. This is very fine and thin, and continued down to the uterus. Its orifice is averse with respect to the ovaria, yet notwithstanding, by the force of the orgasmus veneris, it turns round and grasps the vitellus, which, in its passage through this duct called the infundibulum, receives a thick gelatinous liquor, secreted by certain glands. This, with what it receives in the uterus, compote the white of the egg. By this tube then it is carried into the uterus.

The uterus is a large bag, placed at the end of the infundibulum, full of wrinkles on its inside; here the egg is completed, receiving its last involucrum, and the shell is at last pushed out at an opening in the side of the common cloaca. From the testes in the male being so very large, in proportion to the body of the creature, there must necessarily be a great quantity of semen secreted; hence the animal is falacious, and becomes capable of impregnating so many females. The want of the vesicule seminales is in some measure supplied by the convolutions of the vasa deferentia, and by the small distance between the secreting and excretory organs. The two penes contribute also very much to their short coition, at which time the opening of the uterus into the cloaca is very much dilated, that the effect of the semen on the vitelli may be the greater.

A hen will of herself indeed lay eggs, but these are not impregnated, and yet appear entirely complete, except that the small black spot, which comes afterwards to be the rudiments of the chick, is not here to be observed. After having observed the contents of the abdomen and thorax, we next proceed to examine the parts about the neck and head.

These creatures, as was observed of fowls in general, have no teeth, which would have been needless, as they swallow their food entire; but their tongue is tough, its made pretty firm, lest it should be hurt by the sharp points of the grain they feed on. It is of a triangular figure and pointed before; and as by the depending posture, their meat is in hazard of falling out of their mouths, to prevent this, there are several small pointed papillae hanging out upon their tongue and palate, with their points inclined backwards, allowing an easy passage to the food, but hindering its return.

We have here no velum palatinum, uvula, or epiglottis, and in place of two large holes opening into the nose, there is only a long narrow rima supplied with pretty strong muscles, and such another supplies the place of a glottis. The creature has a power of shutting both at pleasure; and the nature of their food seems not only to exempt them from the hazard of its getting into the nose or trachea, but its sharp points would hurt an uvula or epiglottis, if they had any. Hence we see with what difficulty they swallow dough or other sort of food that can be easily moulded into any form.

Their cranium is more cellular and cavernous than ours, by this means their heads are light, yet strong enough to resist external injuries; for the enlarging the diameter of bones contributes to their strength. By this cavernous cranium the organ of smelling is considerably enlarged; and further, singing birds, as is observed by Mr Ray and Mr Derham, have this cavernous structure of the brain still more observable; and we are told that the cavity of the tympanum communicates with the cells; but this seems rather founded on theory than matter of fact. Their brain is covered with the common membranes, but its external surface is not formed into so many gyres or convolutions as ours. Its anterior part is quite solid, of a cineritious colour, and so far has a resemblance of the corpora striata, as to give rise to the olfactory nerves. The whole of it appears to us as imperfect, and we can scarce determine whether there be anything analogous to a third or fourth ventricle; neither the corpus callosum, fornix, nates, or testes, &c. can be observed here; which parts therefore cannot be imagined as absolutely necessary for the functions of life, since we find these creatures perform them sufficiently well. We may perhaps think these serve a particular use in man, who is a rational creature, but then quadrupeds enjoy them in common with man. These protuberances, &c. seem rather to depend on the different disposition of the several parts, being variously connected, and meeting in different directions in different places, than their being absolutely necessary for any particular use; and the uses that have been assigned to different parts of the brain by authors, seem to have no foundation but in the author's fancy.

Their organ of smelling is very large and well provided with nerves; hence they have this sensation very acute. Ravens and other birds of prey give a sure proof of this by their being able to find out their prey though concealed from their sight, and at a considerable distance.

Those birds that grope for their food in the waters, mud, &c. have large nerves which run quite to the end of their bills, by which they find out and distinguish their food.

The anterior part of their eyes (instead of having the sclerotic coat continued, so as to make near a sphere as in us) turns all of a sudden flat; so that here the sclerotic makes but half a sphere; and the cornea rises up afterwards, being a portion of a very small and distinct sphere; so that in these creatures there is a much greater difference betwixt the sclerotic and cornea than in us. Hence their eyes do not just out of their heads as in man and quadrupeds. As most of these creatures are continually employed in hedges and thickets, therefore that their eyes might be secured from these injuries, as well as from too much light when fling in the face of the sun, there is a very elegant mechanism in their eyes, which is a membrane rising from the internal canthus of the eye, which at pleasure, like a curtain, can be made to cover the whole eye, and this by means of a proper muscle that rises from the sclerotic coat and passing round the optic nerves runs through the musculus oculi attollens (by which however the optic nerves are not compressed) and palpebra to be inserted into the edge of this membrane. Whenever this muscle ceases to act, the membrane by its own elasticity again discovers the eye. This covering is neither pellucid nor opaque, both which would have been equally inconvenient, but being somewhat transparent, allows as many rays to enter as to make any object just visible, and is sufficient to direct them in their progression. By means of this membrane it is that the eagle is said to look at the sun. Quadrupeds, as we mentioned before, have a membranacilittans; but then it only can cover that part of the eye which is never covered by their eye-lids.

Besides, all fowls have another particularity, whose Bourfe noire is not so well understood; and that is a pretty long black triangular purse rising from the bottom of their eye just at the entry of the optic nerve, and stretched out into their vitreous humour, and one would imagine it gave some threads to the crystalline. To this the French (who probably were the first who took notice of it in their dissections before the Royal Academy) give the name of bourfe noire. This may possibly serve to subdue some of the rays of light, that they may see objects more distinctly without hurting their eyes. It has a connection with the vitreous, and seems to be joined also to the crystalline humour. If we suppose it to have a power of contraction, (which may be as well allowed as that of the iris) it may alter the position of the vitreous and crystalline humours, that the rays from any body may not fall perpendicularly upon the crystalline; and this seems to be necessary in them, since they cannot change the figure of the anterior part of their eye so much as we can do; and as this animal is exposed often to too great a number of rays of light, so they having no tapetum, have the bottom of their eye wholly black on the retina; and in consequence of this fowls see very ill in the dark.

They have no external ear, but in place thereof a tuft of very fine feathers covering the meatus audito-hearing, which easily allow the rays of sound to pass them, and likewise prevent dust, or any insect from getting in. An external ear would have been inconvenient in their passing through thickets and in flying, &c. A liquor is separated in the external part of the ear or meatus auditorius to lubricate the passage, and further prevent the entrance of any insects, &c. The membrana tympani is convex externally, and no muscles are fixed to the bones of their ear, which are rather of a cartilaginous consistence; any tremulous motions impressed on the air are communicated in these creatures, merely by the spring and elasticity of these bones; so probably the membrane is not to be offended as in the human ear, where this is done by muscles. The cochlea and semicircular canals are very distinct and easily prepared.

**Chap. VI. The Anatomy of a carnivorous Fowl.**

We come next to the birds of prey, and for an example shall take a stenhill. The principal difference to be observed in them, is in their chylopoietic vili-cera, which may be accounted for from their different way of life.

Immediately under their clavicles, you will observe ingluvies, the oesophagus expanded into their ingluvies, which is proportionally less than in the granivorous kind, since their food does not swell so much by maceration, and for the same reason there is a less quantity of a menstruum to be found here. They have also a ventriculus succenturiatus plentifully flored with glands, situated immediately above their stomack, which we see here is evidently membranous, otherwise than in the granivorous kind; and this difference, which is almost the only one we shall find betwixt the two different species of fowls, is easily accounted for from the nature of their food, which requires less attrition, being easier of digestion than that of the other kind; nevertheless it seems requisite it should be stronger than the human, to compensate the want of abdominal muscles, which are here very thin.

The same mechanism obtains in this creature's duodenum, that we have hitherto observed. As being a carnivorous animal, its guts are proportionally shorter than those of the granivorous kind, for the reason first given, viz. its food being more liable to corrupt, therefore not proper to be long detained in the body, and for that reason it has no intima ceca, of which the other species of fowls have a pair. The difference in their wings, backs, and claws are obvious, and have been already in some measure observed.

**Chap. VII. The Anatomy of Fishes.**

Aqueous animals are generally divided into such as have lungs, and such as want them. The first species differ very considerably from an ox or any other quadruped, and are not easily procured; so that all we have to say on fishes, shall be taken from that species, which is not provided with respiratory organs.

Of these we may first observe, that they have a very strong thick cuticle composed evidently of a great number of scales laid one on another like the tiles of houses; this among other arguments serves to prove the human epidermis to be of a squamous structure.

In the next place these creatures have neither anterior nor posterior extremities, as quadrupeds and fowls; for their progression is performed in a different way from either of these species of animals; for this purpose they are provided with machines properly consisting of a great number of elastic beams connected to one another by firm membranes, and with a tail of the same texture; their spine is very moveable towards the posterior part, and the strongest muscles of their bodies are inserted there. Their tails are so framed as to contract to a narrow space when drawn together to either side, and to expand again when drawn to a freight line with their bodies, by the assistance of this broad tail, and the fins on their sides, they make their progression much in the same way as a boat with oars on its sides and rudder at its stern. The perpendicular fins situated on the superior part of their body keep them in equilibrium, hindering the belly from turning uppermost, which it would readily do, because of the air bag in the abdomen rendering their belly specifically lighter than their back, but by the resistance these fins meet with when inclined to either side, they are kept with their backs always uppermost. The best account of this matter we have in the treatise before mentioned, viz. *Bellii de motu Animalium*, Part I. chap. 23.

It may be next observed, that these creatures have nothing that can be called a neck, seeing they seek their food in an horizontal way, and can move their bodies either upwards or downwards as they have occasion by the contraction or dilatation of their air bag; a long neck, as it would hinder their progression, would be very disadvantageous in the element they live in.

The abdomen is covered on the inferior part with a black-coloured thin membrane resembling our peritoneum. It is divided from the thorax by a thin membranous partition, which has no muscular appearance; so that we have now seen two different sorts of animals that have no muscular diaphragm.

These creatures are not provided with teeth proper for breaking their aliment into smaller morsels; as what made the food they use is generally small fishes or other animals that need no trituration in the mouth, but spontaneously corrupt, and gradually dissolve into a liquid chyle. Their teeth serve to grasp their prey and hinder the creatures they have once caught from escaping again. For the same purpose the internal cartilaginous basis of the bronchi, and the two round bodies situated in the posterior part of the jaws, have a great number of tenter-hooks fixed into them in such a manner, as that anything can easily get down, but is hindered to get backwards. The water that is necessarily taken in along with their food in too great quantities to be received into their jaws in deglutition, passes betwixt the interstices of the bronchi, and the flap that covers them. The compression of the water on the bronchi is of considerable use to the creature, as we shall explain by and by.

The oesophagus in these creatures is very short, and scarcely distinguished from their stomach, feeding their food lies almost equally in both. The stomach is of an oblong figure. There are commonly found small fishes in the stomach of large ones, still retaining their natural form, but when touched they melt down into a jelly. From this and the great quantity of liquors poured into their stomachs, we may conclude that digestion is solely brought about in them, by the dissolving power of a menstruum, and that no trituration happens here.

The guts in these animals are very short, making only three turns, the last of which ends in the common cloaca for the feces, urine and semen, situated about the middle of the inferior part of their bodies.

What we call the pancreas, is by some named the intestinali ceca. It consists of a very great number of small threads, like to many little worms, which all terminate at last in two larger canals, that open into the first gut, and pour into it a viscid liquor, much about the place where the biliary ducts enter. Their intestines are connected to the back-bone by a membrane analogous to a mesentery. No lacteals have been yet observed, and it is probable, their aliment is taken in by the mesenteric veins.

Their liver is very large, of a whitish colour, and lies almost in the left-side wholly, and contains a great deal of fat.

The gall-bladder is situated a considerable way from the liver, and sends out a canal, the cystic duct, bladder, which joins with the hepatic duct just at the entry into and then the gut; some fibres are stretched from the liver to the gall-bladder, but none have hitherto discovered any cavity in these cords; so that in this animal it should seem impossible that the bile can be carried into the gall-bladder in the ordinary way, and consequently must either be secreted on the sides of that sac, or regurgitate into it from the canalis choledochus.

The spleen is placed near the back-bone, and at a place where it is subjected to an alternate pressure from the contraction and dilatation of the air-bag, which is situated in the neighbourhood. Since in all animals, we find the spleen attached to somewhat that may give it a conglomeration, as in the human subject and quadrupeds, it is contiguous to the diaphragm; in fowls it is placed betwixt the back-bone, the liver and stomach; in fishes it lies on the fascia sterni; and since we find it so well served with blood-vessels, and all its blood returning into the liver, we must not conclude the spleen to be an innute pondus, only to serve as a balance to the animal pro equilibrio, but particularly designed for preparing the blood to the liver.

The only organs of generation in this animal are two menstrual bags situated in the abdomen uniting near the podex. These in the male are filled with a whitish firm substance called the milk, and in the female with an infinite number of little ova cluttered together, of a reddish yellow colour called the rose. Both these at spawning time we find very much distended; whereas, at another time, the male organs can scarce be distinguished from the female, nor is there any proper instrument in the male for throwing the seed into the organs of the female, as in other creatures. We shall not take upon us to determine the way whereby the female sperm is impregnated; but we find, that the spawn of frogs consists in the small specks wrapped up in a whitish glutinous liquor; these specks are the rudiments of the young frogs, which are nourished in that liquor, till they are able to go in search of their food. In the same way the ova of fishes are thrown out and deposited in the sand, the male being for the most part ready to impregnate them, and they are incubated by the heat of the sun. It is curious enough to remark with what care they seek for a proper place to deposit their ova, by swimming to the shallow, where they can better enjoy the sun's rays, and shun the large jaws of other fishes. The river fishes again spawn in some creek, free from the hazard of the impetuous stream. But whether this mixture be brought about in fishes, by a simple application of the genitals to each other; or if both of them throw out their liquors at the same time in one place, and thus bring about the desired mixture, is not easy to determine; the latter seems most probable. These creatures are so shy that we cannot possibly get to observe their way of copulation, and are consequently but little acquainted with their natural history.

After raising up the black peritoneum, there comes in view an oblong white membranous bag, in which there is nothing contained but air. This is the swimming-bladder: it lies close to the back-bone, and has a pretty strong muscular coat, whereby it can contract itself. By contracting this bag, they can make the muscles specifically heavier than water and to readily fall to the bottom; whereas the muscular fibres ceasing to act, they become specifically lighter than water and so swim above. According to the different degrees of contraction and dilatation of this bladder, they can keep higher or lower in the water at pleasure. Hence flounders, soles, raia, and such other fishes as want this sac, are found always grovelling at the bottom of the water: it is owing to this that dead fishes (unless this membrane has been previously broke) are found swimming a-top, the muscular fibres then ceasing to act, and that with their bellies uppermost; for the back-bone cannot yield, and the distended sac is protruded into the abdomen, and the back is consequently heavier at its upper part according to their posture. There is here placed a glandular substance containing a good quantity of red blood, and all the red in their body is contiguous to this air bag, excepting the guts. From the anterior part of the bag, go out two processes or appendices, which, according to the gentlemen of the French academy, terminate in their fauces: but there is great reason to suspect that many of their experiments were inaccurately made; and that there is here, as in some places of the human body, an ventriculus aer insitus.

At the superior part of this bag there are other red coloured bodies, of a glandular nature, which are connected with the kidneys. From them the ureters go down to their insertion in the vesica urinaria, which lies in the lower part of the abdomen, and the urethra is there produced, which terminates in the podex.

These last mentioned parts have not hitherto been observed in some species of fishes, whence authors too hastily denied them in all. These creatures have a membranous diaphragm which forms a sac, in which the heart is contained. It is very tense, and almost perpendicular to the vertebrae.

The heart is of a triangular form with its base downwards, and its apex uppermost, which situation it has because of the branchiae. It has but one auricle and one ventricle, because they want lungs; and one great artery. The size of the auricle and ventricle are much the same; the artery sends out numberless branches to the branchiae or gills.

The branchiae lie in two large slits at each side of their heads, and seem to be all they have that chokes bears any analogy to lungs. Their form is semi-circular; they have a vast number of red fibrils standing out on each side of them like a fringe, and very much resemble the vane of a feather. These branchiae are perpetually subjected to an alternate motion and pressure from the water; and we may here remark, that we have not found any red blood, but in places subjected to this alternate pressure; this observation will help us in explaining the action of the lungs upon the blood. Over these gills there is a large flap, allowing a communication externally, by which the water they are obliged to take into their mouths with their food finds an exit, without passing into their stomach; it is owing to these flaps coming so far down, that the heart is said commonly to be situated in their heads.

Their brains are formed pretty much in the same Cerebrum way as that of fowls, only we may observe that the posterior lobes bear a greater proportion to the anterior.

Their organ of smelling is large, and they have a Organ power of contracting and dilating the entry into their smell. nose as they have occasion. It seems to be mostly by their acute smell that they discover their food; for their tongue seems not to have been designed for a very nice sensation, being of a pretty firm cartilaginous substance; and common experiment evinces, that their sight is not of so much use to them as their smell in searching for their nourishment. If you throw a fresh worm into the water, a fish shall distinguish it at a considerable distance; and that this is not done by the eye, is plain from observing, that after the same worm has been a considerable time in the water and lost its smell, no fishes will come near it: but if you take out the bait and make several little incisions into it, so as to let out more of the odoriferous effluvia, it shall have the same effect as formerly. Now it is certain, had the creatures discovered this bait with their eyes, they would have come equally to it in both cases: in consequence of their smell being the principal means they have of discovering their food, we may frequently observe their allowing themselves to be carried down with the stream, that they may ascend again leisurely against the current of the water; thus the odorous particles swimming in that medium, being applied more forcibly to their smelling organs, produce a stronger sensation.

The optic nerves in these animals are not confounded with one another in their middle progress betwixt their origin and the orbit, but the one passes over the other without any communication; so that the nerve that comes from the left side of the brain goes distinctly to the right eye: and vice versa.

The lens crystallina is here a compleat sphere; whereas in men and all other terrestrial animals it consists of two portions of unequal spheres laid on one another: to account for this, it must be considered that these creatures have got no aqueous humour, as the rays that come to their eyes are conveyed through a medium of the same density with that humour in other animals, and consequently would have gone on in a straight line without any refraction till they came to the lens, although they had been provided with an aqueous humour; thus then the rays impinging upon their lens have hitherto suffered no refraction; that they might therefore be sufficiently refracted and meet in a point on the retina, it was necessary the lens should be made more convex than it is in other creatures who have the rays considerably refracted in their passage from the air through the aqueous humour.

As fishes are continually exposed to injuries in the uncertain element they live in, and as they are in perpetual danger of becoming a prey to the larger ones, it was necessary their eyes should never be flat, and in consequence of this they are not provided with palpebrae; but then, as in the current itself, the eye must be exposed to several injuries, there was a necessity it should be sufficiently defended, which in effect it is by a firm pellucid membrane that seems to be a continuation of the cuticle, being stretched over here. The epidermis is very proper for this purpose, as being inflexible and destitute of vessels, and consequently not liable to obstructions, or by that means of becoming opaque.

Whether fishes have a sense of hearing or not is very uncertain: all that has the appearance of an organ of hearing in these creatures is a bone, about the bulk of one half of a common bean, of a particular structure, being very brittle and composed of a great many different segments laid at one another's sides, and situated in a particular form at the side of the brain; is then the idea of sound communicated to them by means of this bone? or does their running away, at stamping hard on the ground or crying loud, depend upon some other kind of sensation? This may possibly be produced in them, by a tremulous motion communicated to their bodies by the circumambient water, which is put in agitation, from the like concussions happening in the air or neighbouring ground.

COMPARATIVE Degree, among grammarians, that between the positive and superlative degrees, expressing any particular quality above or beneath the level of another.