“After these observations it will easily be seen that similar conclusions may be drawn with respect to the hinder limbs of carnivorous animals, which require particular conformations to fit them for rapidity of motion in general; and that similar considerations must influence the forms and connections of the vertebræ and other bones constituting the trunk of the body, and to fit them for flexibility and readiness of motion in all directions. The bones, also, of the nose, of the orbit, and of the ears, require certain forms and structures to fit them for giving perfection to the senses of smell, sight, and hearing, so necessary to animals of prey. In short, the shape and structure of the teeth regulate the forms of the condyle, of the shoulder-blade, and the claws, in the same manner as the equation of a curve regulates all its other properties; and as, in regard to a particular curve, all its properties may be ascertained by assuming each separate property as the foundation of a particular equation, in the same manner a claw, a shoulder-blade, a condyle, a leg, an arm bone, or any other bone, separately considered, enables us to discover the description of teeth to which they have belonged; and so, also, reciprocally, we may determine the form of the other bones from the teeth. Thus commencing our investigations by a careful survey of any one bone by itself, a person who is sufficiently master of the laws of organic structure may, as it were, reconstruct the whole animal to which that bone had belonged.”
After applying the same principle to animals with hoofs, Cuvier comes to a conclusion even more surprising. “Hence,” says he, “any one who observes merely the print of a cloven hoof, may conclude that it has been left by a ruminant animal, and regard the conclusion as equally certain with any other in physics or in morals. Consequently this single footmark clearly indicates to the observer the forms of the teeth, of all the leg bones, thighs, shoulders, and of the trunk of the body of the animal which left the mark. It is much surer than all the marks of Zadig.
“By thus employing the method of observation, where theory is no longer able to direct our views, we procure astonishing, results. The smallest fragment of bone, even the most apparently insignificant apophysis, possesses a fixed and determinate character relative to the class, order, genus, and species of the animal to which it belonged; insomuch that when we find merely the extremity of a well-preserved bone, we are able, by a careful examination, assisted by analogy and exact comparison, to determine the species to which it once belonged, as certainly as if we had the entire animal before us. Before venturing to put entire confidence in this method of investigation, in regard to fossil bones, I have very frequently tried it with portions of bones belonging to well-known animals, and always with such complete success, that I now entertain no doubts with regard to the results which it affords.”
The remarkable correlation between the parts of existing animals having been thus proved by the most rigid and satisfactory tests, we shall inquire with interest for the result, when Cuvier applied the same principles to the fossil animals. If the laws of anatomical structure were the same when these extinct races lived as they now are, these principles will apply equally well to the bones found in the rocks; and though often only scattered fragments are brought to light, the anatomist will be able to reconstruct the whole animal, and present him to our view. Cuvier was the first who solved this problem. The quarries around Paris had furnished a vast number of bones of strange animals, and these were thrown promiscuously into the collections of that city. Well prepared by previous study, this distinguished anatomist went among them with the inquiry, Can these bones live? The spirit of scientific prophecy was upon him, and, as he uttered his inspirations, there was a noise, and behold a shaking, and the bones came together, bone to his bone. And the sinews and the flesh came upon them, and the skin covered them. “I found myself,” says he, “as if placed in a charnel-house, surrounded by mutilated fragments of many hundred skeletons of more than twenty kinds of animals, piled confusedly around me. The task assigned me was to restore them all to their original position. At the voice of comparative anatomy, every bone and fragment of a bone resumed its place. I cannot find words to express the pleasure I experienced in seeing, as I discovered one character, how all the consequences which I predicted from it were successively confirmed; the feet were found in accordance with the characters announced by the teeth; the teeth in harmony with those indicated beforehand by the feet; the bones of the legs and thighs, and every connecting portion of the extremities, were found set together precisely as I had arranged them, before my conjectures were verified by the discovery of the parts entire; in short, each species was, as it were, reconstructed from a single one of its component elements.”
It is hardly necessary to say that, since this first successful experiment, the same principles have been more thoroughly investigated and extended with the same success into every department of fossil organic nature. The results which have crowned the labors of such men as Agassiz, Ehrenberg, Kaup, Goldfuss, Bronn, Blainville, Brongniart, Deshayes, and D’Orbigny, on the continent of Europe, and of Conybeare, Buckland, Mantell, Lindley, and Hutton, and eminently of Owen, in Great Britain, although sustained by the most rigid principles of science, are nevertheless but little short of miraculous; and they demonstrate most clearly the identity of anatomical laws, in all ages, among animals and plants of every size and character, from the lofty lepidodendra and sigillaria to the humblest moss or sea-weed, and from the gigantic dinotherium, mastodon, megatherium, and iguanodon, to the infinitesimal infusoria.
In the sixth place, physiological laws have always been the same upon the globe.
That death has reigned in all past ages over all animated tribes, as it now reigns, so that in that war there has never been a discharge, I need not attempt formally to prove. For the preserved and petrified relics of all the former races, that now lie entombed in the rocks, furnish a silent but impressive demonstration of the former triumph of that great physiological law, which is stamped by the signet of Jehovah upon all existing organic natures—Dust thou art, and unto dust shalt thou return.
Scarcely more necessary is it to attempt to show that the same system of reproduction for filling the chasms which death occasions, and which is now universal in the animal and vegetable kingdoms, has always existed. Indeed, such a system is a necessary counterpart to a system of dissolution. And we find the same phases to this reproductive system in ancient and in modern periods. Organic remains clearly teach us that there have always been viviparous as well as oviparous creatures, and gemmiparous as well as fissiparous animals and plants. The second great physiological law of existing nature has, then, always been the same.
The character of the nourishment by which animals and plants have been sustained has never varied. The latter have ever been nourished by inorganic, and the former by organic, matter. Some animals have ever fed upon the flesh of other animals, as their petrified remains, enclosing the masticated and half-digested fragments of other animals, testify. Other tribes have fed only upon herbs or fruits; and some were omnivorous; just, in fact, as we find the habits of existing animals.
No less certain are we that the processes of digestion and assimilation have ever been unchanged. We find the same organs for these purposes as in existing animals, viz., the mouth, the stomach, the intestines, and the blood-vessels, as the coprolites and the cololites abundantly testify. We infer, therefore, with great confidence, the existence of gastric juice and bile for completing the transformation of the food into blood. Indeed, the discovery by a lady (Miss Mary Anning, of England) of that singular secretion from which the color called India ink is prepared, with the ink-bag of the sepia, or loligo, in a petrified state, shows that the process of secretion existed in these ancient animals; and when we find that in all respects their structure was like that of existing animals, although some of the softer vessels have not been preserved, we cannot doubt but the entire process of digestion, and the conversion of blood into bone, nerve, and muscle, was precisely the same as it now is.