38 



TEXT-BOOK OF EMBRYOLOGY. 



ozoon must enter, this being of the nature of a channel through the membrane 

 the micropyle. In some instances a little cone-shaped projection from the 



. **.*. e ;.: . i" ^ ; 



.: _.0 '. > **.! */ 



*.' :# 



FIG. 23. Fertilization of the ovum of Thalassema. Griffin, 

 j? , Male pronucleus, f, female pronucleus. 



surface of the egg, the attraction cone (Fig. 22, i), either precedes or imme- 

 diately follows the attachment of the spermatozoon to the egg. Instead of a 

 projection there may be a depression at the point of entrance. 



