Charles Robert Darwin. 37 



be here, but if the tree of classification does not suggest a 

 corresponding tree of life to an intelligent mind, it must be 

 because none are so blind as those who will not see. 



Another argument for organic evolution is that furnished 

 us by the structural adaptations of plants and animals to 

 their environment. For example, take the whales and por- 

 poises. The theory of Darwin is that their progenitors 

 were terrestial quadrupeds who by some change in the con- 

 ditions of their life had to become aquatic. The least 

 strongly inherited structures, such as skin, claws, and teeth, 

 would first be affected. Gradually the whole outline of the 

 body would become more fish-like, with bones and muscles 

 better adapted for aquatic locomotion. We find the seals 

 in this condition. The hind legs are much shortened, and 

 directed backwards, so that they do not serve for walking 

 in the least degree, but help to taper off the body in a more 

 fish-like manner. In the whale the hind legs have re- 

 treated inside the skin. But, mind you, every change is of 

 a sort that adapts the structure more completely to its 

 aquatic life. " Thus the arm, which is used as a fin, still 

 retains the bones of the forearm, wrist, and fingers, though 

 they are all inclosed in a fin-like sack. On the other hand, 

 the bat, another mammal, has the fingers enormously elon- 

 gated and covered with a membranous web." The special- 

 creationist explains such things as these, — there are hun- 

 dreds and thousands of them, — by a theory of ideal types 

 to which the Creator is supposed to rigidly adhere. But 

 the adherence is only so far as the needs of the animal re- 

 quire, and the degree of divergence from the typical form 

 everywhere corresponds to the period of changed condi- 

 dions. The theory of adaptive modification accounts for 

 all the facts. The theory of ideal types accounts for noth- 

 ing but the unwillingness of men to give up an old opinion. 



Closely allied to these considerations of adaptive struc- 

 ture is the matter of rudimentary organs — organs, that is, 

 which no longer serve a useful purpose. Such are the 

 teeth of whales that never cut the gums, of birds also ; the 

 wings of insects who never open or use them ; the caudal 

 vertebrae in man, and that miserable appendix vermiform is 

 which so often causes death; the masculine breasts and 

 certain muscles of the scalp and ear, and other similar 

 things. The special-creationist again is ready for us 

 with his theory of ideal types. But it amounts to noth- 



