ADAPTATION 205 



possessing in a measure the same characters. 

 Nevertheless, the transmission of individual en- 

 vironmental adaptations has been established. 



No cases of the transmission of functional 

 adaptations as unquestionable as those of envi- 

 ronmental adaptations are on record. 



It has seemed difficult indeed to devise experi- 

 ments which would prove that the small somatic 

 changes possible during a lifetime are transmit- 

 ted. We were not sanguine enough to suppose 

 that in one generation modifications could be 

 effected and transmitted that would surpass nat- 

 ural variability, and which could, therefore, be 

 recognized as transmitted characters. I have 

 long been convinced that the progressive degen- 

 eration of the eyes of cave vertebrates, coupled 

 with the differential degeneration of different 

 parts, is due and can be due to nothing but the 

 transmission of functional adaptation. I can 

 not altogether regret that this evidence does not 

 seem to have convinced many others. 



The possibility of the transmission of somatic 

 characters to the reproductive cells has been 

 shown by the transplantation of ovaries in chicks 

 by Guthrie. He found that a black hen con- 

 taining an ovary transplanted from a white hen, 

 mated with a white male, did not give white 

 chicks exclusively, as the non-transmissibility of 

 somatic characters would require, but that more 

 than half of the chicks were spotted with black. 

 Also that a white hen containing an ovary trans- 



