OF GERMINATION. 95 



and become root. The plumule is the young bud destii^ed 

 to expand upwards and become stem and leaves. The cotyle- 

 dons are two young leaves, thick and bulky, full of starchy 

 matter to feed the embryo when it shall awake and begin to 

 grow. 



192. In the Wheat-seed (Fig. 312) we find, besides the 

 embryo, a white, mealy mass (a), well known when ground 

 into flour. This mass is evidently intended to answer the 

 same purpose as the starchy cotyledons of the Bean — to 

 nourish the embryo. The radicle {r), the plumule (p), the 

 cotyledon {c), and the albumen (a), are clearly shown. Fig. 

 313 (seed of Four-o'clock) also shows albumen ; here the em- 

 bryo is foiled into a ring around the albumen. Thus we see 

 that the food of the young plantlet is laid up somewhere in 

 every seed, either in the bulky cotyledons of the embryo 

 itself, or in the albumen outside the embryo. 



193. We have, then, seeds albuminous, and seeds exalbu- 

 minous ; seeds two-cotyledoned, and seeds one-cotyledoned. 



LESSON XXV. 



THE SEED BECOMING A PLANT. 



191. We have seen that the ripened seed is a miniature 

 plant, living, but sleeping; packed and sealed up for trans- 

 portation. It may continue to sleep, perhaps, for years, if 



191. Describe the nature and destiny of the radicle; of the plumule; of 

 he cotyledons. 



1 1)2 . Of what does the Wheat-seed consist ? Wliat is the intention of the 

 albumen? the position of it in Wheat? in Four-o'clock? 



193. What seeds are albuminous? exalbuminous ? What seeds are two- 

 cotyledoned ? one-cotyledoned ? 



