LIFE HISTORY OF AN ANGIOSPERM 
35 
RIPENING OF THE OVULE TO FORM THE SEED AND OF THE 
OVARY TO FORM THE FRUIT 
While 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 capsule 
or fruit splits open to discharge them. They fall to the ground and 
he dormant until the following spring when they germinate or com- 
mence 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 proto- 
plasm changes it into additional protoplasm and so the embryo in- 
creases in size, therefore, grows. The pressure of the swollen endo- 
sperm and growing embryo becomes so great that the seed coat 
bursts; the hypocotyl emerges first, dragging the cylindrical cotyle- 
don out of the seed coat and epicotyl with it. The hypocotyl elon- 
gates and extends itself into the soil where it develops a root near 
its tip. The tip enlarges through the storage of starch, manufac- 
tured 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. These runner bulbs the 
third year give origin to another set of runners similar to those 
formed during the second year which also develop runner bulbs at 
their tips. A foliage leaf is also formed by each. The following 
spring (spring of fourth year) one of these bulbs develops into a 
mature sporophyte plant bearing a single flower at the summit of 
its elongated scape. 
