92 Heredity and Eugenics 



a good reason for its truth. The mechanism of the heredi- 

 tary transmission of any character can only be demon- 

 strated when two "crossable" varieties differ in this 

 character. The characters most important to a species are 



FIG. 40. Starchiness in an extracted recessive. On either side normal 

 segregates, in center semi-starchy ear grown from non-starchy seed. 



characteristic of the species. No individual is without 

 them; and this being true, the method of their inheritance 

 must remain unknown. It is often impossible even to tell 

 whether there is a single or a complex set of factors con- 



