a birth or production of a living being degenerating from the proper and usual disposition of parts in the species to which it belongs; as, when there are too many members, or too few, or some of them are extravagantly out of proportion, either on the side of excess or defect. The word comes from the Latin monstrum, a derivative of monstrando, showing; and hence also the box in which relics were anciently kept to be shown was called monstrum. Dugdale mentions an inventory of the church of York with this article, "Item unum monstrum cum ossibus sancti Petri in beryl, et crucifixo in summite." Aristotle defines a monster to be a defect of nature, when, acting towards an end, she cannot attain to it, from some of the principles being corrupted.

Monsters do not propagate their kind, for which reason some rank mules amongst the number of monsters, as also hermaphrodites. Females which bring forth twins are found most liable to produce monsters. The reason probably is, that although the twins are covered with one common chorion, yet they have each their separate amnios, which by their contiguity may chance to grow together, and so occasion a confusion or blending of the parts.

With respect to structure, monsters are of various kinds. Some have an excess or defect in certain parts, such as those which are called acephalous, or want the head; those which have two heads, two arms, two legs, and one body, or which have two bodies and one head, or which have three legs; and those which want the arms or the legs. Others err through an extraordinary and deformed conformation, through an unnatural union of certain parts or viscera, through a great derangement in one or more of their members, and through the extraordinary place which these often occupy in consequence of this derangement or transposition. The monster described by Dr Eller of the Academy of Berlin was of this kind. It was a fetus of nine months, twenty-eight inches long, with an enormous head and frightful countenance: and in the middle of a broad and vast forehead it had a reddish eye, without either eyebrows or eyelids, and sunk deep into a square hole. Immediately below this eye was an excrescence which strongly resembled a penis, with a glans, a prepuce, and an urethra; the part covered with hair was likewise below the nape of the neck. In other monsters we meet with the unnatural union of some parts which, from their destination and functions, ought always to be separate; and the separation of other parts which, for the same reasons, ought constantly to be united. The reader may see the different ways in which the formation of monsters takes place in four memoirs by M. Leméry, inserted in L'Histoire de l'Académie des Sciences, 1738 and 1739.

In the volume published by the Academy of Sciences in the year 1724, mention is made by M. Geoffroy of a monster born in Barres, 1722. This monstrous production consisted of two children without the inferior extremities, and joined together by a common navel. Each of them had a nurse, sucked, and eat pap; and the one sucked whilst the other slept. The reader may likewise consult the second part of Winslow's Memoirs on Monsters, inserted in the volume published by the Academy of Sciences in 1734, where he will find the history of the two very extraordinary twin monsters who exhibited during their lives a great difference in their moral and physical qualities. We are obliged to refer simply to these memoirs, as they are too long for abridgment.

It is observed by Haller, that in some monsters the natural structure has been changed by some shock or passion, whilst in others the structure, independently of any accident, appears to have been originally monstrous; such as when all the members are reversed from left to right, when the person has six fingers, and in many other instances. M. Renou, surgeon at Pommeraye, in Anjou, published an account of some families with six fingers, who were to be found in several parishes of the Lower Anjou, and which had existed there from time immemorial. This deformity was perpetuated in these families even when they intermarried with persons who were free from it. Whether the propagation of these supernumerary organs, which are not only useless, but inconvenient, and even disagreeable, be owing to the father or mother, the children of both sexes are subject to it indiscriminately. A father and mother with six fingers frequently have a part, and sometimes the whole of their children, free from this deformity; but it again makes its appearance, and in a very great degree, in the third generation. From this it appears that such a fault in the conformation is hereditary. (The reader may consult the Journal de Physique for November 1774, p. 372.) This variety of sexdigitary hands and feet is not comprehended in the Recherches sur quelques Conformations Monstrueuses des Doigts dans l'Homme, which is inserted in the Memoirs of the Academy of Sciences for 1771. In the Journal de Physique for August 1776, we find a description of a double uterus and vagina observed in a woman who died in childbirth, by Dr Purcell of Dublin; and in that for June 1788 we have an account, by Baron Dietrich, of a man with seven fingers on each hand. (See also the curious work of Dr Birkow, entitled Monstra Animalium per Anatomen indagata, ii., 4to, Leips., 1828-36.)

Three opinions have been advanced by physiologists as to the causes of monstrosity by excess:—1. Duverney, Winslow, and Haller ascribed excess of organs to the coalition of two perfect germens. 2. Wolf and Meckel considered it as owing to an original excess of productive power. 3. The celebrated Tiedemann ascribed it to abnormal vascular action, modified by pressure. The first opinion has been adopted by Treviranus, Otto, Burdach, Rudolfi, Mayer, and Müller; the second has been defended by Bär and Himly; while the third has been maintained by Serres and Geoffroi St Hilaire. (For further information on the subject, see Lectures on Medical Jurisprudence, by Dr Trail.)

Monsters are more common and more extraordinary in the vegetable than in the animal kingdom, because the different juices are more easily deranged and confounded together. Leaves are often seen, from the internal parts of which other leaves spring forth; and it is not uncommon to see flowers of the ranunculus from the middle of which issues a stalk bearing another flower. Bonnet informs us, that in certain warm and rainy years he has frequently met with monsters of this kind in rose trees. This observer saw a rose from the centre of which issued a square stalk of a whitish colour, tender and without prickles, which at its top bore two flower-buds opposite to each other, and totally destitute of a calyx; and a little above the buds issued a petal of a very irregular shape. Upon the prickly stalk which supported the rose, a leaf was observed which had the shape of a trefoil, together with a broad flat pedicel. In the Memoirs of the Academy of Sciences for 1707 mention is made of a rose from the centre of the leaves of which issued a rose branch two or three inches long, and furnished with leaves. In the Memoirs for 1775, a singular instance is mentioned of a monstrosity observed by Duhamel in an apple tree ingrained with clay. At the place of the insertion there appeared a bud which produced a stalk and some leaves; the stalk and the pedicle of the leaves were of a pulpy substance, and had the most perfect resemblance both in taste and smell to the pulp of a green apple. An extraordinary chamaemelum is mentioned in the Acta Helvetica. Bonnet, in his Recherches sur l'Usage des Feuilles, mentions likewise some monstrous productions which have been found in fruits with kernels, analogous in their nature to those which occur in the flowers of the ranunculus and of the rose tree. He observed a pear from the eye of which issued a tuft of thirteen or fourteen leaves, very well shaped, and many of them of the natural size. He noticed a second pear which gave rise to a ligneous and knotty stalk, on which grew another pear somewhat larger than the first. The stalk had probably flourished, and the fruit had formed. Reynier has mentioned some individuals monstrous with respect to the flower, in the Journal de Physique et d'Histoire Naturelle for November 1785.

These vegetable productions, which are so extraordinary and so contrary to the common course of things, do nevertheless present deviations subject to particular laws, and reducible to certain principles, by distinguishing such as are perpetuated either by seed or by transplanting from those which seem to be only accidental. Monstrosities which are perpetuated exist in the original organization of the seed of the plant, such as marked or curled leaves, &c. The word monster is more properly applied to these irregularities in plants which arise from frequent transplantation, and from a particular culture, such as double flowers; but those monstrosities which are not perpetuated, and which arise from accidental and transient causes deranging the primitive organization of the plant when it comes to be unfolded, being the effect of diseases, of heat or cold, of a superfluity or scarcity of juices, of a deprivation of the vessels contributing to nutrition, of the sting of insects, and of contusions and natural grafts, retain also the name of monsters. Of this kind are knobs or swellings, stunting, gall-nuts, certain streaks, the inoculation of branches, and other similar defects.