THE ANGIOSPERMS 99 
the embryo-sac these are discharged into the sac, when one 
of them fertilizes the egg, thus producing an oospore. It 
is evident that the structure which grows from the pollen- 
grain, and which produces the male gametes, is even more 
inconspicuous and transient as are the structures which pro- 
duce the female gamete. An essential thing to remember 
is that the pollen-grain is an asexual spore and not the male 
gamete, but that it produces male gametes; and that one of 
these gametes fertilizes an egg which is formed within an 
embryo-sac entirely embedded within the ovule. 
The oospore germinates while within the embryo-sac 
and soon differentiates the root, stem, and leaf regions of 
the new sporophyte plant. At this time the wall of the 
ovule hardens, the embryo sporophyte stops growing, and 
the seed is completed. This may remain in a dormant con- 
dition for a long time, but when conditions become favor- 
able, the young plant within bursts the seed-coats and the 
new plant establishes itself and continues its growth under 
new conditions. 
If prepared sections can be had it will be found of inter- 
est to study the phenomena above described, though it will 
not be easy to make out all the different stages in the pro- 
cess. 
Compare this Angiosperm with the Gymnosperm studied 
with reference to the following points: 
Amount’ of chlorophyll work done. 
Protection given to chlorophyll tissue. 
Floral structures. 
Where ovules are borne and how fertilization is effected. 
Time required to ripen the seed. 
