212 Heredity and Eugenics 



of the process at the bottom of the observed changes. In 

 both, there are changes following altered conditions, and 

 there have resulted changes in the organism which are 

 known to occur in many instances, only in these experi- 

 ments some effort was made to test the permanency of 

 the variation and its behavior in subsequent crosses. In 

 both, the change seems to be a germinal one, as is indicated 

 by its behavior in inheritance. Whether the change is a di- 

 rect germinal or an indirect one, due to somatic influence or 

 transmission, the experiments cannot decide. 



Precisely similar are Sumner's experiments in sub- 

 jecting mice to high and low temperatures, where at the 

 end differences were found which were attributed to the 

 effect of the different conditions. Differences there were 

 at the end, but in mammals so variable as mice carefully 

 pedigreed strains free from biotypes should have been used, 

 and adequate parallel controls should have been main- 

 tained. In that controls of critical character were lack- 

 ing and the possibility of biotypes was not eliminated from 

 the stock used, the results obtained are easily attributed to 

 gradual selection of biot>pes or of actuation of latent 

 characters, as weU as to the effect of changed temperatures. 

 As for the question of somatic influence or direct germinal 

 effect, the experiments are not conducted so as to give proper 

 evidence thereon and are capable of any interpretation. 

 The experiments show, however, that changed conditions 

 changed the stock, which change may have resulted from • 

 any of the methods suggested, and the change is appar- 

 ently permanent although the series was too short to answer 

 this question adequately. 



In insects, I have obtained modifications in various 

 ways, some of which will be described in a later portion 



