Page:Evolution of Life (Henry Cadwalader Chapman, 1873).djvu/184

134 exhibited in the embryo of man, is a permanent arrangement in the Sloth, Monotremata, Birds, and Reptiles. Finally, the development of the Skull and Extremities illustrates the same principle of the lower forms of life, representing the undeveloped stages of the higher. Has the Biologist any theory to offer as an explanation of these facts? One may reasonably ask, Why do the flipper of the seal, the foot of the turtle, the wing of the bird, the hoof of the horse, the claw of the lion, the hand of man, etc., develop from a bud? Why are these structures, used for such different purposes, constructed on essentially the same plan? Is there any explanation of the fact that man and the lower animals are undistinguishable in the early stages of their existence, and that the transitory phases through which man passes in the course of development are more or less permanently represented in the lower animals,—that is, that man is not absolutely at any time a Reptile or Dog, etc., but at a certain period exhibits an organization which is undistinguishable from that which later becomes a Turtle or Dog, etc.? It seems to us that the theory of the higher animals having descended from the lower explains perfectly all these facts. We will try to illustrate this view by noticing the effects supposed to be produced on the posterity of a family by their dispersion. After the lapse of ages, subjected to different conditions of soil, food, and climate, the races descending from this family would differ so greatly as regards their appearance, language, and customs that an Ethnologist might doubt if indeed they had come from one stock. If, however, he compared young individuals of these races, and found they resembled one another, and at an extremely early period of life were even undistinguishable, and, further, that sometimes individuals appeared that differed greatly from the race from which they descended, resembling rather a remote, often more barbarous, one; and, finally, that the individuals of a