DISTRIBUTION OF THE CHROMOSOMES 



145 





a 





a' 



• ••• •• ♦.•.^.^« 



.• - 'I ••#/•*/ 



• • • I % 

 ♦ . * . . • •. . • 



a • • • 



^ * * > « A • 



• •• • 





^' 



• « • • 









•% 



c 



• • • * • 



C 



Fig. 48. — Biston hirtaria; a, spermatogonia! chromosomes; a', primary 

 spermatocyte chromosomes (reduced number). Biston zonaria; 6, sper- 

 matogonia! chromosomes; 6', primary spermatocytes (reduced number). 

 Hybrid, out of zonaria femaie by hirtaria male; c, spermatogonia! chro- 

 mosomes; c', primary spermatocytes. (After Harrison and Doncaster.) 



10 



