280 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



a few more cases of a similar type relating to plants grown 

 in the plains or on the mountains. There also it was found 

 to take time, or rather to take the course of several genera- 

 tions, until what was required by the new conditions was 

 reached. Of course these cases are very very few compared 

 with those in which a sudden change of the adaptive character, 

 corresponding to the actual conditions, sets in ; but it is 

 enough that they do exist. 



Would it not be possible at least that adaptations 

 which last for thousands of generations or more might 

 in fact change the adaptive character into a congenital 

 one ? Then we not only should have inheritance of 

 acquired characters, but should have a sort of explanation 

 at the same time for the remarkable fact that certain 

 histological structures of a very adapted kind are formed 

 ontogenetically before any function exists, as is known 

 to be the case with the structures in the bones of 

 vertebrates, for instance. Experiments are going on at 

 Paris, and perhaps in other places of scientific research 

 also, which, it is hoped, will show that animals reared in 

 absolute darkness for many generations will lose their 

 perfectly formed eyes, and that animals from the dark with 

 very rudimentary eyes will be endowed with properly 

 functioning ones, after they have been reared in the light 

 for generations. Such a result indeed would account for 

 the many animals, of the most different groups, which live 

 in dark caves and possess only rudiments of eyes : functional 

 adaptation is no longer necessary, so-called atrophy by 

 inactivity sets in, and the results "acquired 5 by it are 

 inherited. 1 



1 Quite recently Kammerer (Arch. Entw. Mech. 25, 1907, p. 7) has pub- 





