SEED. GERMINATION 



II 



having the same number and relation of parts as in the other examples. 

 But here the cotyledons are thin and papery, and the whole germ is 

 immersed in the nutritive endosperm. The chief store of food is thus 

 not in the germ itself, but m the surrounding endosperm. 



Fir.. 4. 



Castor oil {Ricin^is communis), i. ii. iii., seed from outside, in longitudinal and in 

 trans\'erse section, iv. v., seedling with seed-coat burst but cotyledons still enveloped 

 in endosperm, vi , the saiue cut longitudinally, vii., hypocotyl straightening, endo- 

 sperm still adhering to cotyledons viii., established seedling, with expanded 

 cotyledons and tirst plumular leaves. (-'; natural size.) 



The germination of the Castor-Oil seed corresponds in its external 

 features to that of the Charlock. But here the germ, lying in close con- 

 tact with the endosperm, extracts the food from it, and absorbs it into 

 itself, while the endosperm gradually shrivels. As the seed-coat 

 is thrown off, the cotyledons turn green and expand. The dry 

 remains of the endosperm may then be seen still for a time adhering 

 to their lower surfaces ; but ultimately it falls away. Here the 



