286 HEREDITY AND ENVIRONMENT 



this character, as well as other quantitative dif- 

 ferences between parents which appear to 

 blend in the offspring, such as Castle's case of 

 ear length in rabbits, is not due to a single fac- 

 tor, as in the case of Mendel's tall and dwarf 

 peas, but to several factors. Consequently in 

 the formation of the germ cells there is not a 

 clean segregation of all the factors for tallness 



Fig. 63. Blending inheritance of size in rabbits; the skulls 

 of two parents are shown in 1 and 3, of their intermediate 

 offspring in 3. (From Castle.) 



