26 



Elementary Botany 



If we sow in some soil specimens of the following seeds — 

 Broad Bean, Acorn, Beech, Cress, Cabbage, Castor Oil, Pine, 

 Date, and Wheat— and watch the germination as it takes place, 



m 



Fig. 44. — Seeds of Pinus Pinea in dif- 

 ferent stages of germination. /,ripe 

 seed in longitudinal section : s, sper- 

 moderm ; f, endosperm ; w, radicle of 

 embryo ; c, the cotyledons ; jv, the mi- 

 cropyle end of seed, with the rootlet 

 directed towards it. //, germination 

 commencing: A^ spermodermj s, 

 ruptured, and rootlet, w, protruding; 

 7-, red membrane inside spermoderm ; 

 X, ruptured embryo sac : B, portion 

 of spermoderm removed ; 5, endo- 

 sperm : C, longitudinal section ; c, 

 cotyledons : ZJ, transverse section. 

 ///, germination complete, the coty- 

 ledons, c, unfolding, and the hypo- 

 cotyledonary part of stem, he, elon- 

 gated, the main root, 7w, developing 

 lateral rootlets, w' . (After Sachs.) 



Fig. 45.— Gemiination oi Phoenix doc- 

 iylifera. /, transverse section of seed 

 before germination. //, ///, IVy 

 different stages of germination. A^ 

 transverse section of seed at jc, jr, in 

 IV\ B, at xy ; C, at 23. The fol- 

 lowing letters refer to all the figures : 

 — c, endosperm ; j, sheath of cotyle- 

 don ; si, its stalk ; c, apex, forming 

 an organ of absorption by which the 

 endosperm is entirely removed, the 

 growing end occupying the place 

 of the absorbed endosperm ; w, pri- 

 mary root ; iv'j secondary root ; b', 

 y, leaves succeeding the cotyledon ; 

 b'\ the first foliage leaf; A, pileo- 

 rhiz?. In 5, C, the folded lamina is 

 seen cut across. (After Sachs.) 



we shall find that there is a great difference with regard to the 

 growth and development of the cotyledon during the process. 

 In exalbuminous seeds, where the cotyledons are thick and 



