12 



BEREDITY AND SEX 



be ahown in the figure (D) } it passes to one pole. Each 

 secondary spermatocyte produces, therefore, two cells — 

 one with six, the other with seven chromosomes. These 

 cells become Bpermatozoa (EE r ), the ones with seven 

 dm imoa .Hies are the female-producing spermatozoa, the 

 ones with six chromosomes are the male-producing 







Fig. 21. 



spermatozoa. These two classes of spermatozoa are 

 present in equal numbers. 



If we >tudy the body cells of the female protenor, we 

 find fourteen chromosomes (Fig. 22, A). Twelve of 

 these are the ordinary chromosomes, and two, larger 

 than the rest, are the sex chromosomes. At the synap- 

 sis stage all of the chromosomes unite in pairs, including 

 the two aex chromosomes. When the process is finished, 

 there are seven double chromosomes (Fig. 22, B). 



