66 



GENETICS IN RELATION TO AGRICULTURE 



mosomes only are drawn in black to indicate that they are the ones pri- 

 marily concerned in the determination of sex. Similarly in 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 



FIQ. 32. Diagram to show chromosome relations in the inheritance of sex in Drosophila 



ampdophila. 



black. The reduction division in the female results in a 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, however, the separation of 



