SPECIAL CASES OF SEX-INHERITANCE 



247 



At the next division all the chromosomes in the 23 

 group divide, likewise all in the 24 group divide. 

 There are produced two spermatozoa containing 24 





^ 



5/ 







4»V 



Xe 



F 



^fV* 



*l^> ' 







Fig. 120. — Human spermatogenesis according to von Winiwarter, a, 

 spermatogonia! cell with duplex number; h, synapsis ; c, d, e,f, first spermato- 

 cytes with haploid number of chromosomes ; g, first spermatocyte division, 

 sex chromosomes (below) in advance of others ; h, two polar plates of later 

 stage ; i, first division completed ; j, second spermatocyte with 23 chromo- 

 somes ; k, second spermatocyte ^ath 24 chromosomes ; I, second spermato- 

 cyte division ; m, two polar plates of later stage. 



