846 



PHYSIOLOGY. 



supporting units, the so-called columns of Sertoli. In regard to the 

 spermatogenic cells, we see an entirely different state of affairs. The 

 function of each spermatogenic cell is nothing else but to undergo 



Fig. 382. Schema to Indicate the Process of Maturation of the 



Spermatozoa. ( BOVERI. ) ( HOWELL. ) 

 1, Primary spermatocytes. 2, Secondary sperm at ocytes. 3, Spermatids. 4, Spermatozoa. 



Fig. 383. Diagram Showing Essential Facts in the Maturation 

 of the Egg. ( WILSON.) 



1, First polar body. 2, Division of tirst polar body. 3, Three polar bodies. 4, Female 



2, Division of tirst polar body, 

 pronucleus. 



karyokinesis and form two cells, called mother-cells. Each mother- 

 cell performs the similar function and gives rise to two other cells, 

 called daughter-cells; but these cells differ from their two consecu- 

 tive predecessors. They do not multiply further, but in the 



