6 



PHYSIOLOGICAL GENETICS 



I Ine of the elementary conceptions of classic genetics is, of 

 • oursc, that one and the same phenotype may be hereditary or 



only a modification, and examples of this arc found in all lines 

 of genetic work. But very rarely has the question been raised 



Fig. 1. — (.Continued.) 



as to whether or not there is a physiological connection between 

 both phenomena, which might be attacked experimentally. 

 Some beginnings are found in the earlier work of Tower (1906), 

 who claimed that in Lcptinotarsa he could produce mutations or 



