22 



HOW A PLANT GETS OUT OF THE SEED. 



5. Maize. The embryo of corn is much more complex than the 

 pea, bean, apple or squash. In a previous paragraph I called at- 

 tention to the embryo with its single cotyledon, the large amount 

 of food found in the mealy part of the maize which the embryo 

 uses in its development. Maize kernels which have been placed 

 in sand and kept in a warm place may be examined in forty-eight 

 hours. The embryo is much larger than the dry grains because of 

 the water it has taken up. The seed-leaf never leaves the kernel, 

 but the plumule soon elongates in the presence of moisture and 

 heat. The radicle at the lower end also elongates. A maize ker- 

 nel three or four days in the soil shows a small projection. If 

 this is carefully laid out the student will be able to see that the 

 plumule consists of a succession of very small leaves in specimens 

 that are well out of the ground. The small leaves have flattened 

 out, the lower leaf is nothing but a scale, not green like the ex- 

 panded leaf. Let us now examine some of the plants with good 

 developed roots. Fig. 27. From the lower end of the 



Figure 27. 



Figure 28. 



Seed with weak s;erminat!on except, 

 pop corn on the right, s scutellum 

 underneath; '' plumule. 



root in the seed, numerous small fibrous 

 roots may be seen. These produce other 

 small rootlets. The root-cap may be seen 

 at the tip, and back of it the small root- 

 hairs which have fastened themselves to the soil particles, with 

 a kind of mucilage they have formed. Let us examine other 

 seedlings. You are sure to find some where roots come from 

 the seed near the plumule. 



In others, especially such as are germinated on moist paper, 



Germination of good seed. 

 r primary root in figure to 

 the right with root hairs. '' 

 secondary roots; / p'.umule 



