PART II 

 Tne Period or Fertili2;ation 



The period of fertilization involves: 



(1) The transportation of the gametes to the site normal for the species where en- 

 vironmental conditions are suitable for gametic union (Chap. 4), and 



(2) Fertilization or the union of the gametes (Chap. 5). 



The union of the gametes may be divided into two phases, viz.: 



( 1 ) The primary phase which is terminated when the sperm has made intimate con- 

 tact with the egg's surface, and 



(2) The secondary phase or the fusion of the two gametes resulting in the initiation 

 of development. 



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