THE PHYSICAL BASIS OF MENDELISM 



571 



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. 100.— Diagram showing chromosome relations in the inheritance of sex 

 in Drosophila melanogaster. {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, 



