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 













<#' 





FIG. 120. Human spermatogenesis according to von Winiwarter. a, 

 spermatogonial cell with duplex number; b, 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 ; /, second spermatocyte with 23 chromo- 

 somes ; k, second spermatocyte with 24 chromosomes ; /, second spermato- 

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



