38 



INBREEDING AND OUTBREEDING 



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

 9, th.e elimination of three out of four of the oocytes taJdng 



SPERMATOGENESIS 

 i 



Spermato- 0^ 



Moltiplicatien ^ 

 r pcnorf A 



fi 



Growth period -< 



Ob6EN£SIS 



i 





/ \ 



r ® ^ 



A 



Sp!?ffiS?yte \^j I P*i'"i''« "^ Chro™oson,e= J ^^^-j Primary oocyte 



f \ > deducing division J A 



Secondary /^ 

 spermato- \C^o 

 cyte 



,^-/ V ^J\ Secondary oocyte 

 yV # \ (ovum and f iret 

 ^ ' polar bodyj 



/' , Y Mature, ovum ,. 

 / j and polar bodies 



/ 

 /% 1 Mature ovum 



Zygote. of , l\ f\ fpU Jiomber of 

 fertilized [ ^ \ \ chromosomes 

 ovum witii V ° ^ / restored 



FiQ. 9. — Diagram of gametogeneeis 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 &^^. 



Fertilization consists in the fusion of one Q^'g with one 

 sperm, thus bringing back the double number of chromo- 



