458 PHARMACEUTICAL BOTANY 
CARPELLATE CoONE.—The carpellate cone arises on a short 
branch arising slightly from the end of the main stem of the female 
plant. It consists of a fleshy central axis bearing peltate mega- 
sporophylls. Each megasporophyll bears on the inner surface of 
its expanded outer portion two megasort or ovules. Each mega- 
sorus when mature consists of a megasporangium or nucellus sur- 
rounded by a single integument, the latter being perforated by a 
narrow tubular opening or micro- 
pyle leading to a small cavity or 
pollen chamber at the end of the 
nucellus. (See Fig. 348.) 
Within the nucellus is devel- 
oped one megaspore mother cell 
_ which by division gives rise to 4 
megaspores or embryo sacs. Only 
one of these persists, the other 
three perish. 
GAMETOPHYTES.—The male 
gametophyte begins to develop 
from the young pollen grain 
(microspore) while the latter is still 
within the microsporangium. The 
pollen grain divides to form 2 
Ais, RAO aging alae ce cells, a smaller one or prothallial 
Zamia. B, microsporophylls bearing cell and a larger cell. "The larger 
on their lower surfaces many micro- cell then divides to form a genera- 
sporangia. (From “‘A Textbook of Gen- ti 
@ C 
dali Buswr® bp nite Dadi 6 ell and a tube cell. There 
Moacidlles Co. Publiches results a 3-celled, undeveloped 
male gametophyte or mature pollen 
grain. ‘These are liberated by the bursting of the wall of the 
microsporangium of the now ripened male cone with its separated 
microsporophylls, and are carried by winds. Some are carried to 
the ripened carpellate cones of female Zamias. Some of the 
pollen grains sift between the megasporophylls and come to rest 
about the ovules. Some of them become caught in a mucilagi- 
nous fluid at the outer end of the micropyle and are sucked into 
the pollen chamber. Upon reaching the pollen chamber they 
resume their development. Each pollen grain germinates 
