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 
\ 
i 
ZA 
/ 
ase 
NN 
| REDUCTION 
Fig. 32.—Diagram to show chromosome relations in the inheritance of sex in Drosophila 
ampelophila. 
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 
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