204 DARWINISM AND THE PROBLEMS OF LIFE 



These peculiarities of the coat cannot be explained 

 by the Lamarckian principle. We will not speak of 

 the hairs and protuberances, as to which it is quite 

 unintelligible how such structures, which only act when 

 they are formed and have never been used, can be 

 strengthened by exercise. But let us take a simple 

 case. The Lamarckians would explain in the following 

 way the hard inner edge of the crab's pincers, which 

 grow in the above manner. The shell of the pincers 

 was thin at first. The crab then formed the habit of 

 seizing its prey with the pincers, and using them as a 

 weapon. By the continuous pressure of the claw-fingers 

 on the inner side in bringing them together, the shell 

 gradually hardened at the edges, in much the same way 

 as the fingers of seamstresses or violinists develop a 

 harder skin by pressure. Once the inner edge of the 

 crab's claws had become thicker by this continuous use, 

 and it came to have young ones, these would have a 

 thicker shell at the part in question from birth, owing 

 to heredity, and it would be increased in the course of 

 generations until the actual claws were formed. 



The comparison with the skin of the finger seems to 

 be helpful, but we have really to deal here with two 

 totally different facts. The human skin is alive, and the 

 living substance can certainly be strengthened by use, 

 as the muscles of the athlete's arm show. But the 

 crab's shell is dead ; and dead structures do not become 

 better, but, if anything, worse by use. They get used 

 up, like a steel spring that has been long in use. 



When the coat was still connected with the living 

 skin, when it was still in the process of being formed 



