IV ' EVOLUTION OF SNAKES 161 



toes afford an example of hereditary characters acquired 

 through disuse, of which I shall treat in the following chapter 

 under the title " Degenerated Organs," and, conversely, this 

 deterioration itself shows that strength and skill are really 

 inherited. This degeneration or deterioration must, however, 

 among us, as we wear boots, be somewhat greater than in the 

 barefooted Arabs, and therefore the latter must be from their 

 birth more fitted to use their toes than we. At the same 

 time it is known that our babies still make grasping move- 

 ments with their toes. 



Lamarck explains the origin of the elongated body in 

 snakes by the exertions they make in order to force them- 

 selves through narrow holes. It is evident from the preced- 

 ing that I should not hesitate in certain cases to allow that 

 such efforts on the part of an animal to elongate any organ 

 for a d-efinite purpose might result in a hereditary modifica- 

 tion. But Lamarck's views on the effects of use have been 

 so much neglected, for the very reason that here, as in other 

 cases, the examples brought forward by him are not con- 

 vincing. It seems to me inconceivable that the elongated 

 body of a snake could have been produced in such a 

 way. 



But the origin of the elongated bodies of creeping 

 vertebrates is really a great enigma. 



Not only snakes, but the Blind worm (Anguis fragilis) and 

 other animals have acquired, along with the degeneration of 

 the limbs and the development of a creeping habit, a worm- 

 like form of body. If this could be considered as due to con- 

 stantly repeated stretching out, as a rope or an india-rubber 

 tube can be at last made longer by continual stretching, 

 Lamarck's explanation could not be so flatly rejected. But 

 in all these cases the elong^ation is connected with an increase 

 in the number of vertebrae — in some a very great increase. 



M 



