594 THE WONDER OF LIFE 



interest, and it sliould be repeated by some other investi- 

 gator on some other type. It shows us how much may 

 happen in an individual lifetime. It suggests that an 

 individual fish imprisoned in a perfectly dark cave would 

 become bhnd. In the next generation the atrophy of the 

 eye would probably be greater, since the offspring would 

 experience the darkness from birth while their parents 

 experienced it only from the date of imprisonment. It is 

 Ukely that the absence of light-stimulus would inhibit the 

 development of the eye. Thus blind fishes in caves might 

 be accounted for in terms of individual loss through disuse. 

 If the degeneration of the eye continued to increase after 

 the second generation, that would prove the hereditary 

 accimiulation of an acquired character. On another 

 theory, bhndness might arise in caves as a germinal 

 variation and, being possibly advantageous, become 

 a racial character. A constitutionally blind race would 

 not show any power of getting back its weU-developed 

 eyes on re-exposure to light, but a modificationaUy blind 

 race would. 



A drastic change in the surroundings often makes the 

 organism quiver in its inmost parts, and curious modifi- 

 cations, that we do not as yet know the meaning of, are 

 brought about. Thus OgnefE has shown that Axolotls 

 kept in darkness and starved at the same time become 

 blanched — an experiment which may throw some light 

 on the whiteness of some cave animals, such as the Proteus 

 of the Carinthian caves. In the Axolotls the black pig- 

 ment cells atrophied and were destroyed by the ever-ready 

 body-guard of phagocytes, which carried off the pigment. 

 This goes on not only in the skin, but in some of the internal 

 organs, which also lose their black pigment-cells. 



