138 BOTANICAL GAZETTE [FEBRUARY 
(1) The female gametophyte—In the liverworts the gametophyte 
is a green, independent plant. It is the conspicuous generation, 
the sporophyte being comparatively small and never entirely inde- 
pendent. Here the gametophyte generation, beginning with the 
spore mother-cell and extending to the fertilization of the egg, is a 
complex plant, of which the egg, the culmination of the gametophyte, 
constitutes only a very small part. In the mosses the disparity 
between the gametophytic and sporophytic generations is not so 
marked, but the gametophyte is still predominant and independent, 
while the sporophyte never becomes entirely independent. In the 
ferns the sporophyte has become the conspicuous, independent gen- 
eration, and the gametophyte is much reduced. In most cases the 
gametophyte is still a green independent plant, although it is so small 
that it is likely to be overlooked by the layman. . In the heterospor- 
ous forms the gametophyte is still smaller, develops little or no 
chlorophyll, and shows but little differentiation. Compared with 
the liverworts or mosses, or even with the homosporous ferns, the 
interval between the reduction of chromosomes and the fertilization 
of the egg has been immensely reduced. 
In the gymnosperms the gametophyte is entirely dependent, being 
parasitic in the sporophyte at all stages of its development. Although 
there is a more or less prolonged period of nuclear division before 
cell walls are formed, the ancestors of these gametophytes were doubt- 
less cellular from the beginning of their development. In Gnelum 
Gnemon, cell walls are formed only in the lower portion of the gamet- 
ophyte, in the upper portion the nuclei lying free in a common layer 
of cytoplasm. Any one of the free nuclei of the upper portion seems 
capable of functioning as an egg nucleus. In other species of the 
same genus no walls are formed even in the lower portion, all the 
nuclei lying free in the general cytoplasm. In the angiosperms, 
both the conditions shown by the genus Gnetum are found, but 
reduction has proceeded much farther. A considerable tissue 8 
formed in the lower portion of the gametophyte in Sparganium, 1D 
the grasses, and to a less extent in some Compositae and other forms; 
the tendency, however, is toward the free nuclear condition already 
reached by the latter type of Gnetum. The gametophyte of Peper 
mia, with its sixteen free nuclei, one of which functions as an €88 
