PTERIDOPHYTES 
I6 7 
a single layer of cells; while the inner cell develops 100-200 or more 
sperm mother cells. 
Polypodiaceae. In the Polypodiaceae the antheridium is derived 
from the outer cell following the periclinal division, as in the case of the 
leptosporangiate sporangium. In this cell there 
appears first the funnel wall, which cuts off the 
basal ring cell; then the dome wall appears, 
intersecting the funnel wall and outlining the 
central cell ; and finally the cap or cover cell is 
cut out of the dome cell, completing the ring 
cell (fig. 392). These divisions result in three 
peripheral cells investing a central one, the 
former producing the wall of the antheridium, 
the latter the sperm mother cells, usually thirty- 
two in number (sometimes sixty-four). There is 
thus a decrease in the output of sperms in passing 
from Marattiaceae to Polypodiaceae, just as in 
the case of the spores, but it is much less ex- 
tensive. The sperm is large and spirally coiled, 
consisting of a large body (chiefly nucleus) and 
a conspicuous cytoplasmic beak, from which 
forty to fifty long retrorse cilia arise. 
Archegonium. The archegonia appear late 
in the history of the gametophyte, being de- 
veloped on the ventral side in the region of the 
etophyte of fern bearing 
apical notch (fig. 391). Their development is antheridia; in the upper- 
very uniform, and follows the usual course most antheridium on the 
11 T> .... 11 .1 right side the funnel and 
among ptendophytes. By a penclmal wall the d l ewallshaveappeared; 
superficial initial is divided into the primary i n the three other com- 
neck cell and the inner cell ; and by another P lete antheridja the cover 
transverse division the latter becomes the central e '. ^ or 
pleting the three peripheral 
cell and the basal cell (fig. 393, a). This row of cells; the central cell has 
three cells primary neck cell, central ceil, and developed sperm mother 
basal cell is perhaps the most commonly ob- 
served stage in the development. The primary neck cell produces a 
neck of three or four tiers (fig. 393, b-d), with four cells in each tier. 
The central cell produces the axial row, the first division resulting in 
the primary neck canal cell and the primary ventral cell. Among the 
Marattiaceae the primary neck canal cell produces two neck canal cells; 
