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and growth; minerals enlarge by the juxtaposition of particles only.
Vitality, moreover, enables animals and vegetables to resist to a certain degree the influence of physical laws. This is very remarkable in individuals of the higher classes of the animal kingdom, which are able to retain their own temperature in every state of atmosphere, and in every change of season and climate.
Individuals have exposed themselves voluntarily to the air of ovens, at temperatures from two hundred and sixty degrees to three hundred and fifteen degrees of Fahrenheit's thermometer, without any very great inconvenience, while water was boiling and meat baking in the same atmosphere. Very lately the whole of two ships' crews wintered in about seventyfive degrees of north latitude in perfect safety, where the temperature of the air was, for many weeks together, almost constantly below-30°, and where they became so accustomed to severe cold, that the atmosphere, when at zero, felt mild and comfortable. These facts show a power of resisting the operation of external causes, which is possessed by no substances except such as are endowed with life, and is, probably, possessed in some degree by all that are. For, although vegetables and the lower orders of animals are not capable of resisting to the same extent the influence of heat and cold, yet they all show in some measure the existence of the same power.' p. 4.
Animate bodies have this farther distinction, that they all terminate their existence in death.' When the vital principle has departed, the materials which entered into their composition obey physical laws, and undergo changes and decomposition. Some parts, as the teeth and bones of animals, and the trunks and branches of trees, resist for a time, but all finally submit to the inevitable law of creation, that dust must return to dust. The line of demarkation is not so evident between animals. and vegetables, and most naturalists have failed in their attempts to point it out. Locomotion has been supposed by many to be a distinctive characteristic of the animal creation, but this is possessed by some marine plants, and is denied to the oyster and many other species of animals. A certain degree of motion is enjoyed by nearly the whole of the vegetable kingdom. The roots of most plants will change their direction in pursuit of water, the tendrils of some will attach themselves to objects that approximate without touching them, the leaves of all will turn to the light, and some, like
those of the Heliotrope, and even the common sunflower, perform nearly a diurnal revolution. Vegetables,' says Linnæus, 'grow and live; animals grow, live, and feel.' But what proof is there, that the sensibility of some plants, that of the sensitive, for example, is not as great as that of the corals, madrepores, and zoophytes generally? The plant certainly gives more indication of sensation than the animals referred to, and we know of no reason to induce us to believe, that they are actually endowed with any greater degree of sensibility. It has been well remarked by Smellie, that life, without some degree of sensation, is au incomprehensible idea.'
Real distinctions, however, between animals and vegetables do exist, and must be sought in their intimate structure and composition, in the nature of their food, in the manner of taking and the mode of digesting it. Animal substances contain all the elementary principles of which vegetables are composed, and azote or nitrogen is always found in them in addition. From this circumstance the odor emitted during combustion has been named as a test, by which the presence of animal or vegetable matter could be determined, and some stress is laid on it by Dr Ware. It is observed, however, by Mr Murray, in his System of Chemistry, that of all the products of the vegetable system, the juice of the Carica Papaya is the one which approaches most nearly to animal matter, and it might indeed be regarded as a variety of it, if its origin were not known.' The glutinous part of wheat, caoutchouc, or Indian rubber, and some other vegetable products give out, when burning, an odor very analogous to that from animal matter, under the same circumstances. It is doubtful, therefore, whether this can be regarded as affording a distinctive character between the productions of the two kingdoms, and we shall no doubt be disappointed if we expect to find any one circumstance, by which vegetables and animals may be distinguished from each other. Dr Ware very judiciously remarks, that
The distinction must be sought in the general structure, the general mode of existence, and the purposes of existence in the And in a few words we may say, that animals differ from plants in being furnished with internal organs for the purpose of digesting food, instead of absorbing it by roots from the earth; in being furnished with organs, which render them capable of moving
from place to place, or at least of moving one part of their bodies in some other part; in having powers of sensation, perception, and volition, by which they acquire a knowledge of the existence and qualities of other bodies besides themselves, and form some sort of relation or connexion with them; and in being obviously intended, by the possession of those organs and powers, to be conscious of and to enjoy existence.'
Of the various classifications of the animal kingdom, that of Linnæus is probably the best known, and was for a time universally adopted.* The greatest objection to it arises from the facts, that it brings together, in some instances, animals of very dissimilar properties and habits, that it does not sufficiently regard the various characters of the different objects of animal nature arising from difference of structure, and that it disregards, in fine, too much the study of compara tive anatomy, on which every distribution of animals should be founded.
The division proposed by Lamarck, a profound French naturalist, is hardly known in this country, and is not well calculated to answer the objects for which a classification should be formed.
A new and improved arrangement has been adopted within a few years, and seems likely to supersede all others. We are indebted for this to the greater attention, which is now bestowed on comparative anatomy, and without a thorough knowledge of which zoology cannot be advantageously studied. The classification to which we allude, and which is far more perfect than any that preceded it, though that of Linnæus may be considered as having furnished the basis of it, is contained in the new work of Cuvier, entitled 'Le Règne Animal,' and we are glad to perceive that Dr Ware has given the general outlines of it in the present edition of Smellie.
Many philosophers and naturalists have appeared willing at different times to degrade man by classing him with several animals of a lower order; and even Linnæus himself ranked him with bats, monkeys, and lemurs, merely because the number and arrangement of their incisor or cutting teeth in each jaw were similar to his. A thorough knowledge of
*He divided animals into six classes, viz. Mammalia, Aves, Amphibia, Pisces, Insecta, and Vermes.
comparative anatomy, however, has taught naturalists of the present day, that every classification, in order to be useful, must rest on the double basis of external and internal structure,' and that one or two unimportant coincidences are not a sufficient reason for placing animals, which differ in many essential particulars, in the same class or order. Comparative anatomy also teaches us, in spite of the speculations of some philosophers, that man differs essentially from all other animals in his physical, as well as in his intellectual faculties, that he is the only animal that naturally walks erect, and that, though some may surpass him in the delicacy of some one organ, as those of some of the senses, for example, yet on the whole the combination of his bodily powers is so wonderful, and capable of such astonishing effects, as to entitle him to the most elevated rank in the scale of living beings.
A minute examination of the structure, both internal and external, of apes, baboons, and monkeys, has satisfied naturalists, that they are separated by an immense interval from the most inferior variety of the human race, and the necessity therefore became obvious of adopting some classification, founded upon permanent and important characters, which should place man in the rank to which he was entitled from his great physical and moral superiority. All animals are, therefore, divided by Cuvier in the first place into two grand divisions, viz. into vertebral, embracing those that have a spine or vertebræ, and into invertebral, comprehending all those that are destitute of it. These are subdivided into the following classes.
1. VERTEBRAL ANIMALS.
1. Mammalia, or those which suckle their young,
The two first of the above classes are warm blooded, and the two last cold blooded.
II. INVERTEBRAL ANIMALS.
6. Crustacea, as the lobster and crab.
8. Vermes, or worms, as the leech and earth worm. 9. Zoophytes, as the star fish, sponges, corals and madrepores.
Each of these classes is subdivided into several orders, these into genera, and these last into species. As it is foreign to our purpose to give a complete view of the classification of animals, we shall confine our notice of it to the first class, which is, perhaps, the most interesting, and the subdivisions of which are different in many respects in the arrangement of Cuvier from that of Linnæus.*
The Mammalia are divided into the following orders; First, Bimana, or the two handed animals. Man is the only example of this order. Second, Quadrumana, or four handed animals, embracing apes, baboons and monkeys, all of which have hands, though imperfect ones in comparison with those of man, on all four extremities. Third, Carnivora, or carnivorous animals. This order comprehends four varieties. The first includes bats; the second the hedgehog and mole; the third the bear, polecat, wolf, dog, lion, tiger, &c; and the fourth the seal and some other amphibious animals. Fourth, Rodentia, or gnawers; the squirrel, rabbit, beaver, and jerboa, are examples of this order. Fifth, Edentata, or animals that are destitute of teeth, or provided only with the canine and grinding ones. In this order are placed the sloth, armadillo, and ant eaters. Sixth, Ruminantia, or ruminating animals. This is a very extensive and well marked order, having several important characters, but being distinguished especially by the one that gives it its name, that of bringing up the food, for the purpose of mastication, after it has been swallowed. The camel, dromedary, ox, sheep, &c, belong to this order. Seventh, Pachydermata, animals which possess, as the name implies, hard and tough skins. This order embraces all those animals with hoofs, which do not ruminate. To it belong the elephant, mammoth, taper, rhinoceros, horse, hog, &c. Eighth, Cetacea, or the whale tribe, which are often, though improperly, ranked with fishes, from which
* Linnæus divided the Mammalia into the following orders. First, Primates. Second, Bruta. Third, Feræ. Fourth, Glives. Fifth, Pecora. Sixth, Bellua. Seventh, Cete. The distinctive characters of these orders, with the exception of the last, depended on the kind, position, or number of the teeth, and thus animals of very different habits were brought together, from a resemiblance in one comparatively unimportant particular.