THE DETERMINATION OF SEX 



93 



31 



29 



FIG. 40. Anasa tristis. Second spermatocyte division, during which the acces- 

 sory chromosome remains undivided and partakes itself to one of the daughter cells. 

 x, the accessory chromosome; 9, two groups of chromosomes; 19, single accessory 

 chromosomes, each from a cell in the stage of Nr. 18; 30, three daughter nuclei with 

 the accessory chromosome; 31, later stages of the same (each daughter cell forms a 

 spermatozoon). After Edith Pinney. 



