man; and in all physiological probability therefore were the same three thousand years before that period: so that we cannot refuse to admit, that certain forms have, without exceeding the limits above described, been perpetuated from the creation.

From various circumstances, however, as has been already stated, the offspring never exactly resembles the parent; and by the extension of those causes which occasion a difference of character, the variation from the common parent may possibly become so great, and so permanent in individuals of the same species, as to exceed in some respects the difference observable in individuals of different species. Such appears to be the fact, when, in the dog species, we compare the grayhound with the turnspit; or the Newfoundland dog with the Blenheim spaniel: and yet, even in such instances, which perhaps may be considered as comprising the extreme limits of variation, the specific character is never so far obscured, but that a child who had been accustomed to see a variety of dogs, and also of other animals, would recognise the character of the dog in each individual of that species.

It is true, indeed, that it would be difficult not only for a child, but even for the most experienced observer, to define those characters by which the specific resemblance is recognised upon a transient view of the animal. Yet, although not obvious on a superficial examination, nature has not left this point undefinable: for, in almost every instance, the form and number of the bones are so accurately preserved, that, however the colour, or the size and the general form of the body may be altered, we have satisfactory criteria of the species in the points just mentioned. But, of all the constituent parts of the body, this observation holds most eminently with respect to the teeth and in the case of quadrupeds, which principally constitute the highest class of the animal kingdom, and in which class alone any considerable degree of variation is likely to be observed, we have almost always a ready mode of judging of the identity of specific character by an examination of the teeth; for they in almost every instance have teeth, which are entirely wanting throughout the whole class of birds, and often in reptiles and in fish.

In investigating the remote causes of specific variation, we find that domestication is the most general and extensive; and that the effects are produced principally by the joint operation of the following means, namely, diet, general regimen, and the due selection of individuals for the purpose of breeding.*

* Burckhardt observes, in his notes on the Bedouins, p. 111, and 139, that in barren parts of the desert of Arabia, or in seasons of scarcity, camels and sheep do not multiply so extensively as in fertile plains and seasons. A similar observation would probably hold good with respect to the ratio of increase among the Tchutzki and other tribes of north-eastern Russia, and the inhabitants of New Holland or any other part of the world where the supply of food is scanty.

See, on this subject, a letter, published by Sir John Sebright in 1809, on the art of improving the breeds of domestic animals.

While animals exist in a state of nature, it does not appear that the circumstances in which they are placed give rise to much variation, even in their external and fugitive characters. A uniformity of size and colour is usually observable in the several individuals of the same species; as in the instances of the wild cat and rabbit. Nor is the character liable to be changed by intercourse among individuals of different species. Although, for instance, the hare and rabbit are so nearly allied in form and size and colour, we never meet with a hybrid or mule of those species.

In domesticated species a variation first in colour, and then in size, usually takes place, to an extent proportional to the degree of domestication. Cats, which are less subjugated to man than horses or dogs, vary little more than in colour; scarcely at all in size. And in horses, on the same principle, there is a less degree of variation than in dogs. In the dog, which is of all species the most domesticated, the variation extends to the production of an additional toe, and corresponding metatarsal bone in the hind foot.* And in the human species, in the individuals of which, from their varied intercourse and modes of living, the limits of variation may antecedently be expected to have the widest range, there are families having six fingers.

In concluding this part of the subject, I would observe that the principle, which we have just now been examining, is of very great importance as to the basis of a physiological argument with reference to the identity of the human species throughout the world. For, inasmuch as all the variations in colour, form, and size, of the different nations of mankind, come within the acknowledged limits of specific variation in the animal kingdom, we have hence satisfactory physiological proof that all the varieties of the human race may have proceeded from one common parent. Of the truth of the general position indeed, of which the human species is a particular instance, the work of Aristotle now under consideration is in itself a strong argument: for, notwithstanding the lapse of ages which has taken place since it was written, the description of many species is so accurate, as to leave no doubt of the identity of those described by Aristotle with those to which the description is applicable at the present day.†

* Ann. du Mus. tom. xviii. p. 342. pl. 19.

It can hardly escape observation, or fail to excite surprise, that in the work now under consideration, Aristotle usually contents himself with stating facts: he very rarely reasons on their final causes; thus omitting what Cuvier calls one of the most beautiful and useful points in natural history. The following are, I believe, the only instances in which he deviates from mere description. He observes, when speaking of fish, that a great proportion of the spawn of those animals is destroyed in various ways; and that if this were not the case the species would become too

numerous.

(Τὰ μεν πολλὰ ὡς οἱ ἄρρενες ανακάπτουσι, τα δ' ἀπολλυται ἐν τῷ ὑγρα οσα δ' ἂν εκτε κωσιν εις τους τοπους εις ους ἐκτικλουσι, ταυτα σωζεται ει γαρ παντα εσώζετο, παμπλη θες αν το γενος ην εκαστων. p. 169.)

On another occasion he observes, that though the spring is the general season for

SECTION IV.

On those Animal Forms called Monsters, or Lusus Naturæ.

THE subject of the present section is naturally connected with that of the latter part of the preceding: and, although the occasion neither requires nor would justify even a brief examination of the laws which regulate the formation of monsters, or lusus naturæ, as they are often called, especially as they have been lately illustrated by that ardent French physiologist Geoffroy St. Hilaire; it will not be perhaps considered impertinent to make a few observations on those remarkable productions, considered with respect to one of the probable final causes of their existence.

The term lusus naturæ is applied to those natural productions, which vary in any remarkable degree, with respect to form, colour, structure, size, &c. from the general character of the individuals of the same species. The term literally taken, implies a sportive effort of the creative power of nature; and for the purpose of general description there is no objection to this term, being, as it now is, familiarized by long continued use. But as we have no ground for supposing that nature, or, to use the more proper expression, that the providence of the Creator ever acts without some wise and beneficial purpose, we must consider the term in a philosophical point of view, as expressing an effect, of the natural cause of which we are ignorant.

What, then, is the real character of those unusual productions which are denominated lusus naturæ, or monsters; or, in other words, for what end has Providence ordained that such productions should be formed and subjected to our observation? And here, as has been observed in another part of this treatise, it will be found, upon even a cursory examination, that in a lusus nature the character of the species, however obscured, is never lost. There is no ground, in short, for supposing that nature has ever produced such an individual as a chimera or centaur. And Lucretius's scepticism in this point is justified on truly philosophical principles; on the difference namely of the physical constitution of the horse and of man: the horse at the end of his third year being full-grown, while man is yet almost an infant; and a horse being decrepit in his twenty-fifth or thirtieth year, when man is in his full vigour.*

propagation, yet occasionally the rule is set aside; where, for instance, the preservation of the offspring is the result.

(Ορμετικώτατα μεν ουν ως επι το παν είπειν προς την οχείαν την εκρινην ώραν εστιν ου μην τα πάντα γη ποιείται τον αυτον καιρον της οχείας, αλλά προς την εκτροφην των τεκνων εν τοις καθήκουσι καιροις. p. 181.)

Sed neque Centauri fuerunt, neque tempore in ullo

Esse queat duplici natura, et corpore bino

Ex alienigenis membris compacta potestas

Principio, circum tribus actis impiger annis

Floret equus, puer haudquaquam, &c.-Lib. V. 876-889.

In pursuing this investigation, it would be obvious to ask, what are the limits which separate a lusus naturæ from the ordinary individuals of the same species? and we shall soon find that these limits are, in the majority of instances, undefinable.

If, indeed, in comparing the several organs, agreement with respect to number be the criterion, the limits are for the most part fixed. Thus the human hand so very generally consists of five fingers, that an instance of an individual having more or less than five fingers would be justly esteemed an instance of a lusus naturæ. But even number is not always an acknowledged criterion; for, with respect to the teeth, though thirty-two is the usual number in the human subject, yet the instances of persons having only twenty-eight are so frequent, that we can scarcely class them as deviations from the common law.

But if size, or colour, or form be made the criterion, we evidently cannot then fix the limits; for in all these points there is an endless variety in individuals of the same species: so that it might perhaps be truly asserted, that out of the countless myriads of human beings that inhabit the earth, nay even out of all that have existed since the creation, no two individuals would be found to resemble each other exactly, in even any one of those points. And in this wonderful diversity the infinite power of the Deity is distinctly manifested: for, in the exercise of human skill, the most accomplished artist, as soon as he ceases to copy an actual individual, falls into that general similarity of outline by which we are enabled to ascertain his style upon the first view.

If, in the pursuit of our inquiry, we appeal to the distribution of the internal organs of the body, we shall find, that though with respect to many the position is determinable with considerable precision, yet with respect to others, the smaller veins and arteries, for instance, the variation is endless. But-and this most highly deserves our attention-if we consider the uses of the parts with reference to the precision of their position, we shall find, that the position of those is most constant, the uses of which are most important; while the distribution of those parts, the position of which may differ to a considerable extent without inconvenience to the individual, is found to be continually varying.

Now as this law of deviation from the usual structure does not seem at all to depend on the construction of the parts themselves; and as the result is necessarily connected with the well-being, and even the life, possibly, of the individual; we cannot consider this result as the effect of chance, or want of design: for, if chance could be admissible as the cause, why should one class of phenomena be so much more frequent than the other? And with equal or still greater force we may apply the argument to the existence of those productions emphatically called monsters. Probably then, or rather assuredly, these anomalous productions may, in addition to other ends, be con

sidered as proofs of a particular or constantly superintending Providence; and, like the storms which occasionally ravage the surface of the earth, may awfully recall to our minds the power of the Deity, while they at the same time convince us, by the rarity of their occurrence, of the merciful beneficence of his nature.

CHAPTER XI.

CONCLUSION.

IT has been the immediate object of the preceding treatise to demonstrate the adaptation of the external world to the physical condition of man: and, either in considering him merely as an individual, or as a component member of any stage of society, it may be freely admitted that every step in the investigation has tended to confirm this general conclusion, that-whether from chance, (if any philosophical mind acknowledge the existence of such an agent as chance,) or from deliberate design-a mutual harmony does really exist between the corporeal powers and intellectual faculties of man, and the properties of the various forms of matter which surround him; the material constituents of all nature being as evidently adapted to the supply of the wants of his body, as the contemplation of their causes and relations to the exercise of his mind.

We have seen that from the surrounding atmosphere he is constantly supplied with that respirable part of the air, which alone can support the breath of life; and which is demanded for that purpose during almost every moment of his existence. We have seen that from the same source are derived those universal and important agents, water and heat and light, which are equally though not so immediately necessary, as air, to the wants of man. We have seen again, that the mineral kingdom, though it does not directly contribute to the support of life, yet in the form of natural soils sustains the growth of every kind of vegetable; and that on the nutriment derived from this source all animal life essentially depends: we have seen that the same source also supplies those various metallic and earthy bodies, the uses of which are most extensive and important in promoting many of the arts of civilized society. And, lastly, that the advantages derivable from the vegetable and animal kingdoms are, eventually, neither of less extent and importance, nor their adaptation to the physical condition of man less obvious, than those of the mineral and atmospherical.

It would have been easy to demonstrate that an equally obvious