THE LAMARCKIAN THEORY 239 



mained concealed in the jaw bones or they have disap- 

 peared without leaving any traces." 



Lamarck cites as illustrations the ant-eater, whose 

 teeth have disappeared, owing to its habit of swallow- 

 ing food without masticating it, and the baleen whale, 

 which was, for a long time, considered as absolutely 

 toothless, but in whose foetus teeth have been observed 

 to exist. 



"It is an essential part of the plan of organisation 

 of the vertebrates and of many other animals that 

 they should have eyes in the head. The mole, how- 

 ever, which on account of its habits hardly needs to 

 see plainly, has small, almost invisible eyes, because 

 it hardly ever uses those organs. The Aspalax which, 

 like the mole, lives underground and is probably even 

 less exposed to the light, has totally lost the power of 

 sight; consequently, it has only the rudiments of the 

 organs wherein it resides; and moreover, those rudi- 

 ments are absolutely concealed under the skin and 

 other parts which cover them, allowing no light to 

 reach them." The Proteus, which inhabits deep and 

 dark caves, presents the same peculiarities. "It is part 

 of the plan of organisation of reptiles as well as of 

 other vertebrates, that they have four legs attached to 

 their skeleton . . . but snakes acquired the habit 

 of gliding over the ground and concealing themselves 

 in the grass; owing to their repeated efforts to elon- 



