MATURATION OF THE GERM-CELLS 



171 



FIG. 40. Diagram showing the mode of reduction in the number of chromo- 

 somes during the development of germ-cells. The full number is assumed to 

 be four. (After Wilson. ) 



A, B, division of an oogoniumor of a spermogonium, showing the full number 

 of chromosomes. C, Origin of the double chromosomes in the primary 

 spermocyte. D, E, F, division of this cell into two secondary spcrmocytes, each 

 cont.iining two double chromosomes. G, division of the secondary spermo- 

 cytes to form four spermatids, H, each with two single chromosomes and a cen- 

 trosome. 



The mode of reduction is essentially the same in the maturation of an egg, 

 but of tlie four cells that result, the three polar bodies are much smaller than 

 the egg. 



