190 ORIGIN OF NON-SEXUAL CHARACTERS 



evidence of the influence of darkness in causing 

 degeneration of the eyes. He refers to experiments 

 by Uhlenhuth, who transplanted eyes of young 

 Salamanders into different parts of their bodies 

 where they were no longer connected with the optic 

 nerves. These eyes underwent a degeneration which 

 was followed by a complete regeneration. He 

 showed that this regeneration took place in complete 

 darkness, and that the transplanted eyes remained 

 normal when the Salamanders were kept in the dark 

 for fifteen months. Hence the development of the 

 eyes does not depend on the influence of light or on 

 the functional action of the organs. But it must be 

 obvious to any biologist who has thoroughly con- 

 sidered the problem, that this experiment has little 

 to do with the question of the cause of blindness in 

 cave animals. No one ever supposed that cave 

 fishes became blind in fifteen months, or in fifteen 

 years. The experiment cited merely proves that in 

 the individual the embryonic or young eye will 

 continue developing by heredity even after it is 

 transplanted and in the absence of light. But the 

 eye of the Mammal normally develops in the uterus 

 in the absence of light. 



In his remarks concerning Typhlogobkis, a blind 

 fish on the coast of southern California, Loeb seems 

 to be mistaken with regard to the facts. He states 

 that this fish lives ' in the open, in shallow water 

 under rocks, in holes occupied by shrimps.' Accord- 

 ing to Professor Eigenmann the same species of 

 shrimp is found all over the Bay of San Diego, and 

 is accompanied by other genera of goby, such as 

 Clevelandia and Gillichthys, which have eyes : but 

 these fishes live outside the holes, and only retreat 



