io6 Heredity and Eugenics 



modify the action of Mendel's law in a manner similar to 

 that in which the physical laws holding good under theo- 

 retical conditions are modified under conditions existing 

 in nature. 



Granted, then, that Mendelianism is broad in scope, 

 could it have been of great value during the progress of 



FIG. 45. Inheritance of physical condition of endosperm in maize. Parents 

 and Fi generation shown. 



evolution? That it should have been of great value to 

 very primitive forms of life does not seem possible, and even 

 after the origin of sex its precise importance is somewhat 

 problematical. It has disposed of one of the main criticisms 

 against Darwin, at least, that of the swamping effects of 

 intercrossing upon newly arisen characters that are an advan- 

 tage to the species. Since characters are segregated as units 



