Page:Popular Science Monthly Volume 52.djvu/349

Rh of the consequences of the scientific method—consequences which we are pursuing and shall realize, in the moral as well as in the material order, and despite all opposition; and in this way will come the universal triumph of science to assure the highest degree of happiness and morality to men.—Translated for the Popular Science Monthly from the Author's Science et Morale.



N the great family of the backboned animals, to which we ourselves belong, many different kinds of feet and hands are to be found, their shape showing a very wonderful relation to the manner of life of their possessors.

We are not going here to describe the fins of fishes, although many people believe that our feet and hands were developed from fins; we shall only deal with the true feet and hands found in animals higher than the fishes.

When we try to picture the foot or hand of any animal, we naturally think of it as we see it, often covered with fur which to a great extent hides its real shape. In our own feet and hands the true shape is more evident because the skin has lost its hairy covering. To obtain a clear idea of the feet and hands of different animals it is therefore better to limit ourselves to the bones which give them their firmness.

However different feet and hands may be, there is a certain remarkable similarity of plan in them all. In all, as in our own, there is a cluster of bones forming an "ankle" or a "wrist," and then running out from this a certain number of what we may call "rays." In each foot and hand there were once five rays, as there now are in our own, but in many animals this original number has been reduced, as we shall see. Each ray consists of several joints; the first joints are the longest, and are bound together by skin and flesh to form the sole of the foot or the palm of the hand, while the other joints form the free toes and fingers, the skin at their tips carrying nails or claws.

We can all trace this general plan both in our own feet and in our own hands, although in outward form our feet do not resemble our hands, and the work they have to do for us is so very unlike that it may seem surprising they should be built upon the same plan.

The explanation of this similarity of plan is very simple. Once,