396 



SPOROPHYTE OF ANGIOSPERMS 



consists of a row of cells. The synergids, which are partly con- 

 sumed during the entrance of the tube cells and the process of 

 fertilization, usually become entirely disorganized and absorbed 

 during these early stages of germination. The embryo is formed 

 by the repeated divisions of the embryo cell of the pro-embryo. 



B A 



Fig. 275. Stages in the germination of the gametospore of Lepidium, 

 sectional view: A, micropylar end of embryo sac, showing the enlarging 

 gametospore provided with cell wall and attached to wall of sac. B, later 

 growth — s, suspensor; e, embryo cell; en, endosperm cells. C, pro-embryo 

 after first division of embryo cell. D, further divisions of embryo cell, show- 

 ing formation of an epidermis and a central stem region. E, later growth, 

 two growing regions, the cotyledons, appearing on the sides of the stem. F, 

 micropylar end of the embryo sac in which the embryo cell has formed a small 

 plant or embryo, consisting of two cotyledons, c; stem, st, which terminates 

 in the root, r; the endosperm cells, en, are being absorbed by the enlarging 

 embryo; s, suspensor. 



assisted to a varying extent by one or more of the adjoining cells 

 of the suspensor (Fig. 275, C-F). The remaining cells of the 

 suspensor are ultimately disorganized or they may increase 

 greatly in size and themselves become the principal means of 



