THE SEED 16.*) 



is the hilum. It occupies a third of the length of the bean 

 in Fig. 283. The hilum and micropyie are always present 

 in seeds, but they are not always close together. In many 

 cases it is difficult to identify the micropyie in the dormant 

 seed, but its location is at once shown by ^^^ -^ wt 

 the protruding caulicle as germination be- Ql 

 gins. Opposite the micropyie in the bean 

 (at the other end of the hilum) is an eleva- ExtemaPparts of 

 tion known as the raphe. This is formed bean - 



by a union of the funiculus or seed-stalk with the seed- 

 coats and through it food was transferred for the develop- 

 ment of the seed, but it is now functionless. 



.'i()S. Seeds differ wonderfully in size, shape, color, and 

 other characteristics. They also vary in longevity. These 

 characteristics are peculiar to the species or kind. Some 

 seeds maintain life only a few weeks or even days, whereas 

 others will "keep'' for ten or twenty years. In special 

 cases, seeds have retained vitality longer than this limit, 

 lmt the stories thai live seeds, several thousand years old, 

 have been taken from mummies are unfounded. 



309. GERMINATION. The embryo is not dead: it is 



only dormant. When supplied with moistun warmth, <ih<1 

 oxygen (air), it awakes and grows: this growth is germina- 

 tion. The embryo lives for a time on the stored food, 

 lint gradually the plantlel secures a foothold in the soil 



and gathers f 1 for itself. When tin plantlel is finally 



I'lih h> slnti for itself, germination is <<nni>l< /< . 



310. The germinating seed first absorbs water, and 

 sin Us. The si a reh y matters gradual I j become soluble. The 

 seed-coats are ruptured, the caulicle ami plumule emerge. 

 During this process the seed respires freely, throteing off 

 carbon dioxid (<'<>j). Pill a tin box <>r large necked bottle 

 with dry beans or peas, then add water; note how much 

 they swell. Secure two fruit-jars. Pill one of them a 

 third lull of beans ami keep them moist. Allow the 



