214 Heredity and Eugenics 



progeny be modified in the same manner, there are two 

 possible explanations. The incident conditions may modify 

 both soma and germ independently, and they would be 

 similarly modified because both soma and germ represent 

 one and the same group of potentialities; or the observed 

 results can be explained by assuming that incident conditions 

 first modify the soma, and secondarily, through transmission, 

 the modification is incorporated into the germ cell; and 

 thus be interpreted as upholding the neo-Lamarckian idea 

 of the inheritance of acquired soma variations. It follows, 

 therefore, that the germ cells upon which experiments are to 

 be carried out must either be taken from the body of the 

 parent and placed in indifferent media before being experi- 

 mented upon, or they must be in organisms that can under- 

 go no further somatic modifications. In this there could, 

 of course, be no transmission of acquired variations, because 

 no variations are acquired. Moreover, for our purpose 

 any resulting change must be thoroughly tested by subse- 

 quent breeding for many generations. 



When these organisms attain sexual maturity, they have 

 attained all of the somatic modifications, save pathological 

 growths, which it is possible for them to achieve; the onto- 

 genetic development of variations has come to a standstill, 

 the whole activity of the organism is directed to reproducing 

 the species, and further development or divergence in any 

 of its attributes or qualities is forever inhibited. Whatever 

 changes occur, from sexual maturity onward, are pathological 

 or senescent. 



It is possible, therefore, to eliminate from these experi- 

 ments the neo-Lamarckian factor, because the conditions 

 of experiment were not applied until after the parents had 



