182 BOTANICAL GAZETTE [SEPTEMBER 
7. The female gametophyte is formed by free cell division 
of the megaspore, the nuclei dividing by indirect division. 
These nuclei are confined to the apical portion of the spore. 
Several layers of nuclei are formed by repeated tangential and 
radial divisions so that there are six or seven in the apical region 
and one in the basal. Areas of cells are blocked off by proto- 
plasmic radiations passing from the apex outward and inward. 
The walls of the cells are produced by nuclear plates in the final 
division. There is no diaphragm, and at no stage of its develop- 
ment are there nuclei in the lower or the central portions of the 
gametophyte, which at first contains liquid, and finally a semi- 
solid mass of granular matter. 
8. A cushion of cells protrudes through the tripartite cleft 
in the exospore at the apex. From cells in the upper row of 
this cushion a limited number of archegonia develop. The cells 
of this region are markedly smaller than those in the other 
regions of the gametophyte. No part of the archegonium pro- 
trudes from the general level except the cover cells. 
g. The megaspores and gametophytes are nourished by 
matter secreted by the tapetum and passed through the spore 
mother cell membrane, which persists until the spores are nearly 
half grown. 
10. The microspores develop in a fashion analogous to the 
megaspore. A large percentage of the mother cells form 
tetrads, the largest proportion of which are aborted at this 
stage. 
11. The male gametophyte of S. apus consists of a single 
prothallial cell and an ovoid naked mass of potential sperm cells 
arranged in two groups. There is no antheridium, nor is there 
a wall which separates the prothallial from the sperm cells. 
12. The spermatozoid of S. apus is a spirally coiled body; 
that of S. rupestris is of similar shape but much smaller. The 
presence of cilia in either was not demonstrated. 
13. The megasporangia and microsporangia of both species 
open by definite lines of dehiscence. 
14. Fertilization in both species occurs while the spores are 
LS Sa 
