THE PHYSICAL BASIS OF MENDELISM 



411 



the male the three pairs of autosomes which are exactly like those in the 

 female are outlined, but the X-chromosome and the Y-chromosome are 

 drawn in black. The reduction division in the female results in a 



FIG. 75. Diagram to show chromosome relations in the inheritance of sex 

 in Drosophila ampelophila. (From Babcock and Clausen.) 



separation of the members of each pair of chromosomes, so that every 

 secondary germ cell (or egg) contains two large curved autosomes, 

 a small autosome, and an X-chromosome. Consequently as far as 

 chromosome content goes the eggs are all exactly alike. In the male, 



