330 Fish Stories 



the rock, lying there patiently in wait for minute crabs and 

 shrimps, and thoroughly protected from all of its. enemies. 



Its most curious trait is the fact that it is blind. The 

 young ones have small eyes, but with age they fail to de- 

 velop, and when the animal is full grown only the rudiments 

 are left, half covered by the skin. 



Because it does not move about, its fins have become degen- 

 erate, and it does not need eyes to see where to go. Because 

 it hides in dark crevices it has no use for eyes, and by the 

 same process which has caused the blind fishes of the Mam- 

 moth Cave to lose their eyes these little fishes have also 

 gone blind. 



But it is not yet very clear what this process is. We 

 know that without need for eyes, eyes do not develop. We 

 know that the young have eyes, and with the disuse of eyes 

 in the individual, the species also loses it. 



As to this there are two theories, and the final cause is 

 not yet known. It is urged by some that the results of dis- 

 use are inherited, and that because the old blind fish let 

 their eyes lapse, the young are born with eyes defective. 



According to the other theory, the whole matter is regu- 

 lated by the survival of the fittest. Where a fish lives in 

 the dark, the one which cannot see is the best fitted to sur- 

 vive. This theory applies to all cases of degeneration, and 

 on the whole it seems most tenable, as we have no certain 

 knowledge that results of use or disuse ever become heredi- 

 tary. It is often loosely said that my grandfather's environ- 

 ment is my heredity, but we have no certain knowledge that 

 such is ever the case, either with men or fishes. 



The blind goby is most abundant at Point Loma, but it 

 has been lately brought alive to Stanford University from 

 Dead Man's Island, near San Pedro. 



