LIFE HISTORY OF AN ANGIOSPERM 
57 
the synergids and fuses with the nucleus of the egg to form an 
oospore. By this time the tube nucleus has disintegrated. The 
oospore by repeated divisions develops into as many as four embryos 
or young sporophyte plants. Only one of these, however persists. 
The polar nuclei fuse to form the endosperm nucleus which soon 
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 FORM THE SEED AND OF THE OVARY 
TO FORM THE FRUIT 
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 capsule 
or fruit splits open to discharge them. They fall to t'he ground and 
lie 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 
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 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 
