2 PRACTICAL COURSE IN BOTANY 
Fies. 1-8. — The world’s three most important food grains (magnified): 1, sec- 
tion of arice grain; a, cuticle ; b, aleurone, or protein layer ; c, starch cells; d, germ ; 
2, section of a wheat grain; k, germ; s, starch; a, gluten; 1, ¢, t, layers of the seed 
coat; 3, section of a grain of corn; c, husk; e, aleurone layer containing proteins ; 
eg, yellowish, horny endosperm, containing proteins and starch; ew, lighter starchy 
endosperm : the darker part below is rich in oil and proteins, and contains the em- 
bryo, consisting of the absorbing organ, or cotyledon, sc; the rudimentary bud, s ; and 
the root, w. (1, from Circular 77, La. Exp. Station ; 2, from Francé ; 3, from Sachs.) 
2. Why food is stored in seeds.— The one purpose 
for which plants produce their seed is to give rise to a new 
generation and so carry on the life of the species. The 
seed is the nursery, so to speak, in which the germ destined 
to produce a new plant 
is sheltered until it is 
ready to begin an inde- 
pendent existence. But 
the young plant, like 
the young animal, is 
incapable of providing 
for itself at first, and 
would die unless it re- 
ceived nourishment from 
the mother plant until 
Fias. 4-7. —Sections of corn grains showing ; 
different qualities of food contents: 4, 5, small it has formed roots and 
germ and large proportion of horny part, show- leaves so that it can 
ing high protein; 6,7, large germ and smaller pro- 
portion of horny part, showing high oil content. manufacture food for 
fy 
