The Plantlet. 41 



since active protoplasm cannot exist without nourish- 

 ment (13). In the pea, bean, pumpkin and other seeds 

 of this class, the food supply, instead of being stored by 

 itself, as in the corn-grain, is contained within the plant- 

 let or embryo mainly in the fleshy cotyledons. When 

 the food supply of the seed is separate from the embryo, 

 as in corn and many other seeds, it is called the endosperm. 

 It is the food supply of seeds that makes them so val- 

 uable as food for animals. 



56. The Plumule (pi u' -mule). If we look between the 

 cotyledons of the bean plantlet (Fig. 9), at the point of 

 their union with the hypocotyl, we may see a pair of 

 tiny leaves, and by carefully separating these if need be, 

 with the point of a pin, we may discover a minute pro- 

 jection the growing point (67) of the stem between 

 them. These leaves, with the growing point, form the 

 plumule the terminal bud of the plantlet. These tiny 

 leaves become the first true leaves, and the growing 

 point between them develops into the stem and later 

 leaves. By close examination, we may make out the 

 plumule in Figs. 8, 10 and 11. In the pea and corn, it 

 has already made considerable growth. 



57. Thus we see that the plantlet or seedling consists 

 of three parts, viz., the hypocotyl, the cotyledons (in 

 some plants cotyledon) or seed-leaves, and the plumule 

 or terminal bud. 



58. Chlorophyll (chlo'-ro-phyll). Soon after the plant- 

 let emerges from the seed- case, a green color appears in 

 the parts most exposed to light. This is due to the for- 

 mation within the cells of chlorophyll the green color- 

 ing matter of plants. Chlorophyll forms only in light, and 



3 



