(Πρῶτον δ ̓ ἀρκτέον ἀπὸ τῶν ὀστρακοδέρμων, μετὰ δὲ ταῦτα περὶ τῶν μαλακοστράχων, καὶ τὰ ἄλλα δὲ τοῦτον τὸν τρόπον ἐφεξῆς· ἔστι δὲ τά τε μαλάκια καὶ τὰ ἔντομα, καὶ μετὰ ταῦτα τὸ τῶν ἰχθύων γένος, το τε ζωοτόκον καὶ τὸ ᾠοτόκον αὐτῶν, εἶτα τὸ τῶν ορνίθων. μετὰ δὲ ταῦτα περὶ τῶν πεζῶν λεκτέον, ὅσα σε ζωοτόκα καὶ ὅσα ᾠοτόκα δ ̓ ἐστὶ τῶν τετραπόδων ἔνια, καὶ ἄνθρωπος τῶν διπόδων μόνον. p. 112.) It is remarkable that, from the age of Aristotle to nearly that of Linnæus, no systematic classification of animals was attempted; none, at least, was generally adopted. Soon after the commencement of the last century Linnæus directed his attention to the subject; and distributed the whole animal kingdom into six classes, mammalia, birds, reptiles, fish, insects, and worms: in which distribution Lamarck observes that he improved on Aristotle, first, by using the more distinctive term mammalia, and placing the cetacea in that class; and, next, by making a distinct class of reptiles, and arranging them between birds and fish. If this alteration, which has been subsequently adopted by all other zoologists, be made, Aristotle's arrangement of vertebrated animals agrees with that of the present day. And in distributing all other animals into four classes, which Linnæus distributes into two only, Aristotle must be considered as having proceeded upon the more philosophical principle; because the species of these animals, taken collectively, are much more numerous, and much more diversified in their form and structure, than the species of vertebrated animals. Lamarck's objection to Aristotle's arrangement, on the ground of its commencing with animals of a more complicated instead of those of a more simple structure, is, for more than one reason, of little weight: for, in asserting that such an arrangement is contrary to the order of nature, he makes a peculiar hypothesis of his own the basis of that assertion; and, with the exception of Lamarck himself, almost if not all modern naturalists, including Cuvier, adopt the same principle of arrangement as that of Aristotle.

Lamarck objects with more justice to the terms έναιμα and άναιμα, as also to the supposed improvement of some modern naturalists by the substitution of the equivalent terms, red-blooded and white-blooded; because in the second of those two divisions some species are included, as worms, &c. which have red blood. On this ground Lamarck proposed to divide all animals into those which have, and those which have not, vertebræ; or into vertebral and invertebral animals.* And he extended the two invertebral classes of Linnæus to five, and subsequently to ten.†

With reference to the classification of Aristotle, as expressed in his first book, it has been occasionally observed by literary men, who were not familiar with the details of his history, that quadrupeds in general and reptiles are excluded. "The most comprehensive groups into which the greater number of animals may be †Ibid. p. 121, 122.

Philos. Zool. tom. i. p. 116, &c.

distributed," he 66 says, are these: one, of birds; one, of fish ; one, of whales and other cetaceous animals; all of which have blood. There is another group of the όστρακοδέρμα ; another, of the μαλακόσ τρακα ; another, of the μαλακια ; and another, of the έντομα; all of which are without blood. Of those animals which do not come within the foregoing arrangement, there are no comprehensive groups; for no individual type comprehends many species: and there is one type which is unique, affording only a single species, namely, man. Some types afford different species without a difference of specific denomination: thus there are red-blooded quadrupeds, of which some are "viviparous, and others oviparous."

(Γένη δὲ μέγιστα τῶν ζῴων, εἰς ἃ διήρηται τἆλλα ζῷα, τάδ' ἐστίν, ἓν μὲν ὄρνι θων, ἓν δ' ἰχθύων, ἄλλο δὲ κήτους. Ταῦτα μὲν οὖν πάντα ἔναιμά ἐστιν. άλλο δε γένος ἐστὶ τὸ τῶν ὀστρακοδέρμων—ἄλλο τὸ τῶν μαλακοστράκων—ἄλλο τὸ τῶν μαλακίων—ἕτερον τὸ τῶν ἐντόμων. Ταῦτα δε πάντα μέν ἐστιν ἄναιμα—Τῶν δὲ λοιπῶν ζῴων οὐκέτι τὰ γένη μεγάλα· οὐ γὰρ περιέχει πολλὰ εἴδη ἓν εἶδος, ἀλλὰ τὸ μέν ἐστιν ἁπλοῦν αὐτὸ οὐκ ἔχον διαφορὰν τὸ εἶδος, οἷον ἄνθρωπος, τὰ δ' ἔχει μεν, ἀλλ' ἀνώνυμα τὰ εἴδη. Ἔστι γὰρ τὰ τετράποδα καὶ μὴ πτερωτὰ ἔναιμα μεν πάντα, ἀλλὰ τὰ μεν ζωοτόκα τὰ δ ̓ ᾠοτόκα αὐτῶν. p. 10.)

And though there are many species of viviparous quadrupeds, yet they have no collective denomination; but each is distinguished, as in the case of the human species, by its proper name; as the lion, deer, horse, &c. on which account we cannot describe them collectively, but must consider the individual nature and character of

each."

(Τοῦ δε γένους τοῦ τῶν τετραπόδων ζῴων καὶ ζωοτόκων εἴδη μέν ἐστι πολλὰ, ἀνώνυμα δέ· ἀλλὰ καθ' εκαστον αὐτῶν ὡς εἰπεῖν, ὥσπερ ἄνθρωπος εἴρηται, λέων, ἔλαφος, ἵππος—Διὸ καὶ χωρὶς λαμβάνοντας ἀνάγκη θεωρεῖν εκάστου τὴν φύσιν αὐτῶν. p. 10.)

It is interesting to observe that even Cuvier occasionally experiences a similar difficulty in his classification; and expresses himself, with reference to the difficulty, in nearly the same terms as Aristotle. Thus, in introducing his third order of the mammalia, called carnivora, he says, "The forms of the different genera of this order are so various, that it is impossible to range them in the same series: they are therefore divided into several families.* And of one of these families, the marsupialia, to which the oppossum and kanguroo belong, he observes, that "the genera of that family might form a distinct order, so very peculiar is their structure.t And on another occasion he adds, with respect to this same family, that "although the various species so closely resemble each other in many points as for a long time to have been classed in one genus

• Les Carnassiers.-Leurs formes et les détails de leur organisation varient beaucoup-au point qu'il est impossible de ranger leurs genres sur une meme ligne, et que l'on est obligé d'en former plusieurs familles qui se lient diversement entre elles par des rapports multiplies. tom. i. p. 121.

+Les Marsupiaux-pourraient presque former un ordre à part, tant ils offrent de singularités dans leur économie." tom. i. p. 169.

only; they yet differ so widely in their feet, and teeth, and organs of digestion, that, considered with reference to those parts, they might be distributed, not into one but several orders;*-and might constitute even a separate and parallel class of mammalia.†

In addition to the natural groups, enumerated in the distribution above described, Aristotle refers to a few marine animals which principally belong to the zoophytes of Cuvier, without comprehending them under a distinct name. Of that extensive class of animals, called at the present day polypes, which are the fabricators and inhabitants of every variety of coral, he says nothing: and of that still more extensive class, if the term class be not too confined, the animalia infusoria, he was almost necessarily ignorant; most of the species being microscopic.

It appears, from a few scattered notices, that Aristotle had a faint idea that the specific characters and dispositions of animals might be altered, from the effect of food and other circumstances: (τῶν ζῴων τῶν τετραπόδων πολλὴν αἱ χωραι ποιοῦσι διαφορὰν οὐ μόνον πρὸς τὴν ἄλλην τοῦ σώματος εὐημερίαν ἄλλα καὶ πρὸς τὸ πλεονάκις οχεύεσθαι καὶ γεννᾶν. p. 122. Όσα μὲν οὖν μαλακὰς ἔχει τας τρίχας, εὐβοσία χρώμενα σκληροτέρας ἴσχει, ὅσα δε σκληρας, μαλακωτέρας καὶ ἐλάττους. Διαφέρουσι δε καὶ κατα τοὺς τόπους τοὺς θερμοτέρους καὶ ψυχροτέρους. p. 68.) Ενίοτε γίνεται των μονοχρέων ἐκ μελάνων τε καὶ μελαντέρων λευκα—ἐκ δε των λευκων γενων οὐκ ὤπται εἰς μετ λαν μεταβάλλον. p. 71.)

And he mentions particularly one instance of this kind, though his reasoning on the occasion is not admissible in the present state of physiological knowledge. In observing that, "as the actions of animals are determined by their natural affections and physical powers, so their moral habits, and even some of their physical characters, are capable of being altered by their actions;" he says, that "the common hen, if she have fought with and vanquished the cock, will begin to crow, and to imitate the cock in various ways; and her comb will increase, and her plumage alter to such a degree as to make it difficult to determine whether she be really a hen even spurs, though small, will sometimes grow on her legs.

(Ὥσπερ δε τας πράξεις κατα τα πάθη συμβαίνει ποιεῖσθαι πᾶσι τοῖς ζῴοις, οὕτω πάλιν καὶ τα ἤθη μεταβάλλουσι κατα τας πράξεις, πολλάκις δε καὶ των μορίων ἔνια, οἷον ἐπὶ τῶν ὀρνίθων συμβαίνει. Αἵ τε γὰρ ἀλεκτορίδες όταν νικήσωσι τοὺς ἄρρενας, κοκκύζουσί τε μιμούμεναι τοὺς ἄρρενας καὶ ὀχεύειν ἐπιχειροῦσι, καί τό τε κάλλαιον ἐξαίρεται αὐταῖς καὶ τὸ οὐροπύγιον, ὥστε μὴ ξαδίως ἂν ἐπιγνωναι ὅτι θήσ λειαί εἰσιν· ἐνίαις δὲ καὶ πλῆκτρά τινα μικρα ἐπανέστη. p. 302.)

The fact is nearly as Aristotle states it; and, to a certain ex

* Malgré une ressemblance générale de leurs espèces entre elles, tellement frappante, que l'on n'en a fait long-temps qu'un seul genre, elles différent si fort par les dents, par les organes de la digestion et par les pieds, que si l'on s'en tenait rigoureusement à ces caractères, il faudrait les répartir entre divers ordres. p. 170.

+On dirait, en un mot, que les marsupiaux forment une classe distincte, parallèle à celle des quadrupèdes ordinaires. p. 171.

tent, similar facts are observable in the human species as well as in other animals; namely, that the peculiar characters of the female are occasionally obscured, with respect both to the physical form and the moral habits. But, in reasoning on the phenomena, Aristotle mistakes the effect for the cause. The circumstance of having fought with the cock is not the determining cause of the change in the external form of the hen: but the alteration itself in the external form is dependent on, or at least coincident with an imperfect developement, or a subsequent alteration, of the internal structure; which imperfect developement or subsequent alteration determines that degree of masculine courage which prompts the hen to fight, and to imitate the male in other actions.

And so it sometimes happens that, in females of the human species, the feminine form is either never originally developed, or, by age or other causes, becomes so much altered as to lose its usual characters ; (γυνή δε τας ἐπὶ τῷ γενείῳ οὐ φύει τρίχας· πλὴν ἐνίαις γίγνονται ολίγαι, kav sa xataμhvia osй. p. 70.) and, correspondently with these exterior traces of virility, there is often in such cases a masculine temperament of the mind, which marks the character of the virago. And, on the other hand, from analogous causes analogous changes are found to take place in the male of our own species, or of any species nearly resembling our own: for, in such instances, the tone of the voice and the general form of the body acquire a feminine character; and that firmness and resolution, which belong naturally to the male, subside to a greater or less degree into a feminine gentleness.

Aristotle, then, had no philosophical notion of the laws which regulate the occasional variation in the specific form of animals; much less of the limits of that variation: for the accurate developement of which, the scientific world, and more than the scientific world, are deeply indebted to the skilful researches and correct reasonings of Cuvier; whose fame will rest securely on this natural and imperishable basis, when his own and all other artificial systems of classification, for artificial we can see them to be even in the present state of our knowledge, will probably have been overturned by the force of those new views of nature, which must necessarily result from the contemplation of the numerous and varied phenomena which are rapidly accumulating in this department of knowledge. The field, indeed, in which Cuvier has laboured, with such advantage to science as well as honour to himself, is the investigation of the conditions which accompany the developement of individual and specific form and the result of his labours has afforded a splendid instance of the wonderful effect which the powers of the human mind are capable of producing, in a subject apparently of the least intrinsic interest and of the most unpromising aspect. The explanation of his views which I shall now attempt to offer, while it may tend to make known the particular merits of

this philosopher to a class of readers, who at present are acquainted with little more of him than his great name, will certainly accord with the general object of this treatise.

In the preliminary discourse of his work entitled "Ossemens Fossiles," he states that the great principle in the study of comparative anatomy is this-that in every animal the several parts have such a mutual relation, both in form and function, that if any part were to undergo an alteration, in even a slight degree, it would be rendered incompatible with the rest; so that if any part were to be changed, all the other parts must undergo a corresponding change: and thus any part, taken separately, is an index of the character of all the rest. This law of the co-relation of parts is indeed so defined, that even a portion of a bone may often serve to verify the species of the animal to which it belonged. (p. xlv.)

We know how successfully Cuvier has applied the foregoing principle in establishing the true character of fossil species, of which the imperfect remains, or fragments of remains, are both few and of rare occurrence. The permanency however of specific character does not hold in every part of the organisation; and hence there is an occasional impediment to the application of the principle: but the variation never proceeds beyond certain limits; and therefore no more interferes, eventually, with the uniformity of the specific character of animals, than the periodical oscillations of the celestial bodies counteract the general regularity of their motions.

We are now therefore to consider the nature of the disturbing cause, if I may borrow that expression for a moment, which occasionally interferes with the uniformity of specific character. And, with respect to specific forms, it may be remarked, that, although it is to a certain extent true that all organised bodies have the power of producing beings resembling themselves, yet circumstances of temperature, and of quantity or quality of food, and other causes, have usually some influence in the developement of the body of each individual; thereby producing some corresponding variation in the form and, consequently, the resemblance between the parent and offspring is never perfect. But-and this is a fact of the highest importance-there is no ground for believing that such variations proceed beyond certain limits; no ground therefore for believing that any of the above-mentioned circumstances could have produced all the differences perceptible in organised bodies; could have advanced for instance, by a gradual alteration of structure, a lower to a higher species. Experience, on the contrary, founded on an examination of the records of remote antiquity, seems to show that the limits of variation were ever the same that they are now. It appears for instance from the mummies of Egypt, that the general form, and size, and proportions were the same three thousand years since, that they are at present; as well in various other animals as in

* Vid. Cuvier, Oss. Foss. i. Disc. Prelim. p. 75, 80.