THE WALLFLOWER 141 



begin and new organic substances be formed. We 

 see, then, that in this plant the cotyledons have a 

 double function ; they serve at first as stores of ready- 

 made food for the seedling, and afterwards they act as- 

 assimilating leaves, and can manufacture new food on 

 their own account. 



In most of the points described the germination of 

 the Wallflower may be regarded as typical of that of 

 the Dicotyledons generally. For example, the exit of 

 the radicle through the micropyle is very constantly 

 the first stage in germination. The behaviour of the 

 cotyledons, however, differs much in different members, 

 of the Class. In some plants, such as the Broad Bean 

 (Vicia Faba), the cotyledons never rise above the 

 ground at all, but serve simply as storehouses of 

 food, the first assimilating leaves being those of the 

 plumule. In seeds, again, which when ripe contain 

 abundant endosperm, the first duty of the cotyledons 

 is to absorb the food which the endosperm contains, 

 and they do not emerge from the seed (if they do sa 

 at all) until this has been accomplished. 



