SPERMATOPHYTES 215 
consisting usually of two (fig. 478) or three cells, but in Podocarpus 
it sometimes becomes a massive structure of about twenty-five cells. 
There is no well-defined archegonial jacket, and when it is remem- 
bered that there is no special digestive zone about the mother cell, 
it is evident that the nutritive mechanism is not differentiated in 
this group as it is in Ginkgo, or even in the cycads. In the division 
of the nucleus of the ventral cell, which precedes the formation of 
the egg, there is no separating wall formed, and hence no ventral 
canal cell. The ventral nucleus is its only representative, and in 
Torreya it is doubtful whether even this 
appears. The disappearance of the ven- 
tral canal cell and its nucleus is the last 
stage in the reduction of the axial row, 
which thereafter is represented only by the 
egg- 
Male gametophyte. In the development 
of the male gametophyte, the podocarps and 
taxads show a striking contrast. In the Fia 478 ._ Yo ung arche- 
podocarps two to six vegetative (prothallial) gonium of Torreya, showing the 
cells appear (fig. 480); while in the taxads two neck celk and the central 
cell. After COULTER and 
no vegetative cells have been discovered. L AND 
The division of the generative (primary 
spermatogenous) cell into the sterile stalk cell and the body cell is 
as described for the preceding groups (fig. 480); but a striking change 
appears in the fact that there are no blepharoplasts in the mother 
cell, which means that ciliated (hence swimming) sperms are not 
formed. The nucleus of the body cell divides, and this division may 
be accompanied by a separating wall, so that two sperm mother 
cells are formed (taxads); or the nuclear division may not be accom- 
panied by wall formation, so that there are only two mother cell nuclei 
in the general cytoplasm of the body cell (podocarps). In either case 
the division is unequal, so that only one cell or one nucleus functions 
(fig. 479). No sperms are formed, but the mother cell functions directly 
as a sperm, its nucleus being the structure essential in fertilization. It 
has become the habit to call these mother cells that do not form sperms 
internally and discharge them, but function themselves as sperms, 
simply male cells. 
Fertilization. In pollination (by the wind) the pollen grains come 
to rest on the tip of the nucellus, and in the absence of a pollen chamber 
