THE PHYSICAL BASIS OF MENDELISM 



409 



and the other from the male with the chromosomes in full black, unite 

 to form the female zygote shown in the middle of the figure. The 

 combinations of maternal and paternal chromosomes which result in 

 the production of germ cells in such an individual are shown diagram- 



X X 



FIG. 74. Diagram showing consequences of independent segregation of 

 chromosomes in Drosophila ampclophila. (From Babcock and Clausen.) 



matically in the lower portion of the figure. There are eight different 

 ways in which the chromosomes may be grouped in the reduction 

 figures and on the basis of chance any one of these types is as likely 

 to occur as any other. As a result there are sixteen possible combi- 

 nations of chromosomes in the germ cells with respect to the original 



