FERTILIZATION 





in one male nucleus than in the other, bo thai the two ma} appear quite 

 unlike during the later stages. Miss Welsford also in the male 



cytoplasm certain granules which she thinks may represent the vestig 

 of blepharoplasts. 



I 



<f 



r, 

 C 





/• 







F 



(V 



Fig. 123. — Fertilization in angiosperms. 

 A, end of pollen tube from basal portion of style of LUium auratum, showing two male 

 cells and tube nucleus. X 250. (After Welsford, 1914.) B, double fertilisation in / 

 canadense: male and female nuclei about to fuse in egg; second male and two polar nuclei 

 fusing at center of embryo sac; s, synergids, one degenerated; a, antipodalfl 

 C, fusion of sexual nuclei in egg of LUium philadelphicum. X 1000. I [ft* R 

 1918.) D, the second male and two polar nuclei in LUium Martagon. X ~ 

 Nothnagel, 1918.) E, vermiform male nucleus in contacl with egg nucleus in I 

 durum. X 600. (After Sax, 1918.) F, spireme stage of triple fusion nucleus 

 durum, showing distinctness of three chromatin contributions. X 750. 

 G, inclusion of cytoplasm in fusing sexual nuclei of Peperomia I 

 1910.) 



Fusion in Egg. — As already staled, one male nucleus passes into 

 the egg and fuses with the egg nucleus. So far as observations enable 

 one to say, only the male nucleus, and no cytoplasm, enters the egg, a 

 point of much importance in connection with the transmission of heredi- 

 tary characters from the male parent. It would be a matter of extreme 

 difficulty, however, to demonstrate conclusively thai in passing through 

 the egg membrane the male nucleus is absolutely freed of all adherii 

 cytoplasm or chondriosomes; and it must be admitted that such a 

 demonstration has not yet been given in any case. The fusion of the two 

 sexual nuclei probably occurs in most cases very soon after they come 

 in contact, though in certain forms the actual fusion is known to be 



