456 



BOTANY 



a cell-wall, and ultimately elongates into a tube, the proembryo, 

 which divides transversely into one or more cells. 



Development and Structure of the Seed 



The embryo is developed, for the most part, from the lowest 

 cell of the proembryo derived from the fertilised egg (Fig. 390). It 



Fia. 389. — Funlcia ovata. Apex of nucellus, showing 

 part of embryo-sac and egg-apparatus.' A, Be- 

 fore, B, during fertilisation ; o, egg - cell ; s, 

 synergidffi ; (, pollen-tube; n, "nucellus. (x 600.) 



Fig. 390.— Stages in the development of the 

 embryo of Capsella bursa pastoris (A-D). 

 fc, Hypophysis ; e.t, suspensor ; c, coty- 

 ledons ; p, plumule. (After Hanstein, 

 magnified.) 



is represented at first by a multicellular sphere terminating the filiform 

 SUSPENSOR, and becomes differentiated, generally before the seed is 

 ripe, into a radicle, hypocotyl, and one or two cotyledons. There are 



