THE SPERMATOPHYTES — 477 
undergoes rapid division into a large number of nuclei scattered 
about through the protoplasm of the embryo sac. Later cell 
walls are laid down and endosperm is formed. ‘The endosperm 
cells soon become filled with abundant starch which is later to be 
utilized by the embryo during germination. | 
RIPENING OF THE OVULE TO ForRM THE SEED AND OF THE OVARY 
To Form THE FRuitT 
When the embryo and endosperm are being formed, the 
ovule enlarges and its integuments become modified to form a 
hard, horny, seed coat which encloses the endosperm surrounding 
the embryo. The ovary, containing the ovules, has by this time 
ripened to form a three-valved, loculicidal capsule enclosing the 
seeds. 
GERMINATION OF THE SEED AND DEVELOPMENT OF THE MATURE 
SPOROPHYTE 
The seeds are fully developed by June or July when the cap- 
sule or fruit splits open to discharge them. ‘They fall to the 
ground and lie dormant until the following spring when they 
germinate or commence to grow. Each seed absorbs water from 
the ground which stimulates the ferment amylase, contained in 
the endosperm cells, to break up the insoluble starch into soluble 
sugar which passes into solution and diffuses into the cells of 
the embryo, where the protoplasm changes it into additional 
protoplasm and so the embryo increases in size, therefore, grows. 
The pressure of the swollen endosperm and growing embryo 
becomes so great that the seed coat bursts; the hypocotyl emerges 
first, dragging the cylindrical cotyledon out of the seed coat and 
epicotyl with it. The hypocotyl elongates and extends itself 
- into the soil where it develops a root near its tip. ‘The tip 
enlarges through the storage of starch, manufactured by the 
green cotyledon and becomes a bulb. The bulb soon develops 
within it a plumule, the cotyledon withers, and the young 
plant (seedling) passes the following winter in this condition. 
During the next spring the plumule develops into a foliage 
leaf and the bulb gives rise from its base to several slender 
elongated runners, which, at their tips, develop runner bulbs. 
