Page:Popular Science Monthly Volume 15.djvu/257

Rh and it is not too much to say that toward the side of the idea which advocates gradual modification and selection as the rule of life and nature, every unbiased student of natural science will by sheer force of circumstances be led to turn.

The whalebone whales have no teeth, although the sperm whale possesses teeth in the lower jaw; but thereby—that is, as regards the teeth of whales at large—hangs a tale of some importance, and to which our attention may be briefly directed. Among the paradoxes of living nature, no circumstances present more curious features than those relating to the so-called "rudimentary organs" of animals and plants; the subject of these organs, and the lessons they are well calculated to teach, having been recently treated at some length in these pages. Now, the whales furnish several notable examples of the anomalies which apparently beset the pathways of development in animals. The adult whalebone whale is toothless, as has just been remarked; and this fact becomes more than usually interesting when taken in connection with another, namely, that the young whale before birth possesses teeth, which are shed or absorbed, and in consequence disappear before it is born. These teeth never "cut the gum," and the upper jaw of the sperm whale presents us with a like phenomenon for consideration. Nor are the whales peculiar in this respect. The upper jaw of ruminant animals has no front teeth—as may be seen by looking at the mouth of a cow or sheep—yet the calf may possess rudimentary teeth in this situation, these teeth also disappearing before birth. Now, what meaning, it may be asked, are we to attach to such phases of development? Will any considerations regarding the necessity for preserving the "symmetry," or "type," of the animal form aid us here; or will the old and overstrained argument from design enable us to comprehend why nature should provide a whale or a calf with teeth for which there is no conceivable use? The only satisfying explanation which may be given of such anomalies may be couched in Darwin's own words. The embryonic teeth of the whales have a reference "to a former state of things." They have been retained by the power of inheritance. They are the ignoble remnants and descendants of teeth which once were powerful enough, and of organs with which the mighty tenants of the seas and oceans of the past may have waged war on their neighbors. Again, the laws and ideas of development stand out in bold relief as supplying the key to the enigma. Adopt the theory that "things are now just as they always were," and what can we say of rudimentary teeth, save that Nature is a blunderer at best, and that she exhibits a lavish waste of power in supplying animals with useless structures? But choose the hypothesis of development, and we may see in the embryo-teeth the representatives of teeth which in the ancestors of our whales served all the purposes of such organs. Admit that, through disuse, they have become abortive and useless; and we may then, with some