6 BOTANICAL GAZETTE [JANUARY 
itself is used up in the growth of the proembryo. The neck is 
composed of about 12 cells arranged in a single tier (usually). The 
nuclei lie at the larger peripheral end of the cells. In the pointed 
central end there is little cytoplasm. Often there appears to be 
a slight opening among the neck cells, as if in anticipation of the 
entrance of the sperm. 
The course of the pollen tube after reaching the female game- 
tophyte is not always direct. It frequently wanders along between 
the megaspore membrane and the gametophyte, eroding the latter 
more or less, before turning down into an archegonium. Arche- 
gonia that are apparently mature and ready for fertilization may 
be passed and the male cells delivered to archegonia some distance 
farther away from the point of entry of the pollen tube. Very 
commonly the archegonial chamber above each archegonium 
becomes overgrown, so that the tube must force its way down to 
the neck. Some cells are destroyed in its approach, but the way 
is more often prepared by the thrusting aside of the intruding cells 
and the consequent opening up of the previously existing passage. 
When the tube reaches the archegonium its tip is thrust down 
into the immediate neighborhood of the neck cells. The tip is 
then ruptured and the male cells crowd through the narrow passage 
of the neck. Sometimes both male cells enter and more frequently 
only one can be found. The archegonia are often so crowded with 
cytoplasm that the entrance of the male cell causes the extrusion 
of some of it through the neck (fig. 10). The entry appears to be 
violent, for the egg nucleus is commonly driven to the bottom of 
the archegonium and may even be driven through the bottom. 
_ The violent displacement of the egg nucleus shows very clearly 
that the male cells move with considerable force, while the extru- 
sion of the cytoplasm seems to prove that they are not forced in 
by the tube, as has been said to be the case in certain other gym- 
nosperms. It seems clear from the facts just stated that these 
male cells are actively motile, although it is almost certain that 
they have no cilia or other organs of locomotion. -Their large 
size._as well as their vigor of movement makes them conspicuous 
among Coniferales. Such size and movement are matched only 
among the cycads and Ginkgo. 
