10 ELEMENTS OF BOTANY. 



Malt, which is merely sprouted barley with its germination 

 permanently stopped at the desired point by the application 

 of heat, tastes much sweeter than the unsprouted grain, and 

 can be shown by chemical tests to have suffered a variety of 

 changes. 



Germinating kernels of corn undergo great alterations in 

 their structure (see Pig. 12). 



14. The Embryo and its Development. — The miniature 

 plant, as it exists ready-formed in the seed, is called the 

 embryo. In the seeds so far examined the entire contents of 

 the seed-coats consist of the embryo, but this is not the case 

 with the great majority of seeds. 



As soon as the young plants of squash, bean, and pea have 

 reached a height of three or four inches above the ground it is 

 easy to recognize important differences in the way in which 

 they set out in life. 



The cotyledons of the squash increase greatly in surface, 

 acquire a green color and a generally leaf-like appearance, 

 and, in fact, do the work of ordinary leaves. In such a case 

 as this the appropriateness of the name seed-leaf is evident 

 enough, — one recognizes at sight the fact that the cotyledons 

 are actually the plant's first leaves. In the bean the leaf-like 

 nature of the cotyledons is not so clear. They rise out of 

 the ground like the squash cotyledons, but then gradually 

 shrivel away, though they may first turn green and somewhat 

 leaf-like for a time. 



In the pea (as in the acorn, the horse-chestnut, and many 

 other seeds) we have quite another plan, the underground 

 type of germination. Here the thick cotyledons no longer 

 rise above ground at all, because they are so gorged with 

 nourishment that they could never become leaves ; but the 

 young stem pushes rapidly up from the surface of the soil. 



The development of the plumule seems to depend somewhat 

 on that of the cotyledons. The squash-seed has cotyledons 



