MORPHOLOGY OF LEAVES AND FLOWERS 



.621 



Fig. 484 



Fig. 485 



Fig. 484. Embryo sac of Buttercup (.RanuncuVus multifldus). Near the center 

 Is the large endosperm nucleus. The egg is the Inner one of the three cells 

 at the upper end of the sac and lies between the inner ends of the two 

 synergids. The three antlpodals are shown closely crowded at the lower 

 end of sac. 



(After Coulter.) 



Fig. 485. Fertilization in the Fleabane (.Erigeron) ; pt, pollen tube with two 



densely staining bodies (x) ; a, male cell fusing with egg; b, male cell 

 fusing with endosperm nucleus. 



(After Land.) I 



cell. This process in wMeh the sperms or male nuclei fuse with 

 the nuclei of the ^g and endosperm cell is fertilization, and both 

 fusions are designated as double fertilization. 



THE DEVELOPMENT OF THE EMBRYO AND SEED. 



When the fertilized ^g^ germinates, a filament of cells, the 

 suspensor, is usually found. At the end of the suspensor the 

 embryo is developed which, when mature, is more or less sur- 

 rounded by nourishing endosperm which has resulted from the 

 growth and division of the endosperm nuclei. 



