THE PLANT AS A WORKING MACHINE 17 
plant absorbs food material from the ovule. While the em- 
bryo plant is developing, food material is constantly being 
transported into the grain, or ovule, until finally a relatively 
large amount of food material is thus deposited (fig. 12). 
The ripened seed, or grain, consists of the old ovule wall, 
the stored food material, and the embryo corn plant. The 
scale-like bract, or chaff, which surrounded the young ovule, 
often adheres to the ripened grain. In many kinds of plants 
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Fic. 12. Grains of indian corn 
1, a grain with seed-covering partly torn away, showing the root tip (r) and the 
stem tip (s) of the embryo corn plant within the seed. B, a grain showing the 
percentage of different substances that compose it 
the ripened seed or seeds may be surrounded by one or more 
structures, the whole then composing the so-called fruit. 
14. Seed germination. Seeds may lie dormant for a very 
long time or may grow soon after being formed. Under 
favorable conditions the young plant within the seed bursts 
the seed coat and. continues its growth as a new plant. It 
pushes out its root, stem, and leaves and soon assumes the 
appearance of the kind of plant that formed it (figs. 13 and 
1+). In some kinds of plants, when the seed germinates, the 
seed coat remains underground and the stem and leaves grow 
