246 HEREDITY AND SEX 



warter, has attacked the problem (Fig. 120). His 

 material and his methods appear to have been superior 

 to those of his predecessors. His results, while stated 

 with caution and reserve, seem to put the whole 

 question on a safer basis. 



His main results are illustrated in the diagram 













>r||i;^ ^^^ ^^" ■^■• 



^-•* -.-. .»x t?^»:^> 





C'--.^ 



u 



0^^mm 



'iti .'*9«i.'^ 





Fig. 119. — Human spermatogenesis according to Guyer. The sex 



chromosomes are seen in 6-9. 



(Fig. 120). In the male he finds 47 chromosomes. 

 Of these 46 unite at reduction to give 23 double 

 chromosomes — one remains without a mate. At the 

 first reduction division the pairs separate, 23 going 

 to each pole, the unpaired chromosome into one cell 

 only. 



