THE SEED 319 
grows downward into the soil forming the primary root, and devel- 
ops upon itself secondary or lateral roots, all of which giverise to 
root-hairs just above their root caps. Additional lateral roots 
emerge above the scutellar region which ere long attain the size 
of the first or primary root. The caulicle, carrying upon its tip 
the plumule, elongates and forms the stem; the leaves of the 
plumule spread out and turn green to function as foliage leaves. 
The perforated cotyledonary sheath grows out surrounding both 
the root and the stem for a portion of their length. By this time 
Fic, 239.—Different ways in which seedlings emerge from the soil. A, garden 
pea; B, corn; C, Lima bean; g, ground level. (Motter.) 
all or nearly all of the nourishment stored in the endosperm has 
been absorbed and assimilated by the young seedling and the 
coat and scutellum, left behind, gradually decay and disappear. 
The root-hairs absorb nourishment from the soil, the green leaves 
build up carbohydrates, prop-roots make their appearance at the 
first node (joint) above ground, and the seedling grows larger. 
Gross STRUCTURE OF A DocoTyL SEED, PHAsEoLus LuNATUS 
(Lima Bean).—The Lima Bean Seed shows a flattened-ovate to 
somewhat reniform outline. Externally it exhibits a polished 
seed coat which is perforated on its basal side by a minute pore 
