394 



SPOROPHYTE OF ANGIOSPERMS 



nuclei, thus forming the endosperm nucleus through a triple 

 fusion. While this process is probably in the nature of a rein- 

 forcement, enabling the endosperm nucleus to perform its work, 

 it is noteworthy that the qualities of the male parent are trans- 



FlG. 273. Section of the micropylar end of the megasporangium, show- 

 ing the process of fertilization. The tube, t, has passed through the micro- 

 pyle, entered the female gametophyte and ruptured, discharging the male 

 cells. One, d^, is shown fusing with the female gamete, 9, and the other 

 one, cT', is uniting with the two polar nuclei, thus making a triple fusion in 

 the formation of the endosperm nucleus; j, one of the synergids; i, integu- 

 ments. 



mitted to the endosperm cell just as though this fusion were a 

 sexual process. 



127, The Germination of the Gametospore.— After fertiliza- 

 tion the endosperm nucleus divides repeatedly, and usually the 

 resulting nuclei become arranged about the walls of the sac-like 

 gametophyte which may now be called the embryo sac (Fig. 

 274). Later the endosperm cells develop walls and by further 

 division completely fill the embryo sac with cells. This mass of 

 cells is called the endosperm and the method of its development 

 is exactly similar to that of the female gametophyte of the gym- 



