10 



BOTANY OF THE LIVING PLANT 



and exposed to the light. They expand as green leaves, and help the 

 nutrition. Thus in the Charlock the seed-leaves serve first for storage, 

 and afterwards for carrying out nutrition. It is not an uncommon 

 thing in plants for a part to serve more than one purpose, sometimes 

 simultaneously, sometimes successively. 



Fig. 3. 



Charlock (Brassica Sinapis). i. ii., seed with and without seed-coat, iii.-vii., 

 successive stages of germination. Natural size. 



A third type of germination may be seen in the Castor-Oil plant 

 (Fig- 4)- The seeds are large, and covered by a mottled, brittle 

 seed-coat, which is easily removed, disclosing the semi-transparent 

 contents. These consist of a thin film covering the massive oily 

 endosperm, a nutritive store which is not represented in the previous 

 examples. It can easily be split down the middle in the plane in 

 which the seed is flattened (ii. vi.). The germ is then disclosed, 

 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 



