38 



INBREEDINa A^D OUTBREEDING 



are similar in all essential features, as may be seen in Fig. 

 9, the elimination of three out of four of the oocytes taking 



SPSRMATOOKNBSIS 



I 



$pj5.jto. 



Spermatocyte 



Secondary 

 — rwato- 

 cytes 



Spertnato 



imr 



Spera- 

 uosoa 



Multiplication 

 p*riod 



056EN£SIS 



i 



.^ 



(^ h. 



Odgonia 



•■ Growth period -* 



Pairing of Chrorsosomes 

 Reducing division J 



\ 



/ \ 



Primary oocyte 



Secondary oocyte 



(cvoft) and f iret 



polar body) 



Mature ovup ^, 

 and poiar bodies 



Mature ovin 



WUn* f) 1^^ 



. mmber cS 



Fio. 9. — Diagram of gametogenesis showing the parallel between maturation of the aperm 

 cell and maturation of the ovum. (After Guyer.) 



place in order that their store of nutritive materials may 

 go to make one large egg. 



Fertilization consists in the fusion of one egg with one 

 sperm, thus bringing back the double number of chromo- 



