BROWN: APOGAMY IN PHEGOPTERIS POLYPODIOIDES 27 
The first outgrowth, after forming an elongated flat structure 
several cells in thickness and width, broadened into a prothallium 
with a slight sinus. Tracheids formed in the thickened region 
at the center. The second outgrowth continued its develop- 
ment as an elongated, thick, club-shaped structure bearing 
tracheids near the base. The third outgrowth at a very early 
stage formed a slightly elongated prothallus-like structure, 
distinctly notched and bearing a series of very short tracheids 
in the elongated portion. 
On the very irregular prothallium shown in Fic. 11 a normal 
embryo was formed near the base of the archegonial cushion, 
while near the sinus an apogamous sporophyte developed. 
This appeared as a cellular mass surrounded by proliferations, 
from which the first leaf was formed. 
Of the apogamous outgrowths represented by Fics 12-20, 
those of Fics. 12, 16-18, and 20 originated as cellular masses 
on the archegonial cushion of the prothallia; those of Fics. 
I3-I5 originated as lobes from the margins of the prothallia 
and that of Fic. 19 as a lobe in the sinus. The cells in most of 
these marginal lobes were large. The prothallium shown in 
FIG. 13 was somewhat elongated and bore many lobes on the 
margin of its apex. One of these lobes, after elongating into a 
prothallus-like structure, several cells in width and one cell in 
thickness, formed a cellular mass. From this were given off 
three branches. The development of the apogamous outgrowth 
was continued by a reversion to a broad thick prothallium with 
a lobed apex. A series of tracheids were formed in the thickened 
region of this outgrowth. All the branches given off by the 
cellular mass were curled after the manner of a normal leaf, 
in the early stages of their development, and one resembled 
a normal leaf in shape. However, this was the extent of the 
similarity between these branches and normal sporophytic 
eaves. The branches were only one cell in thickness and no 
tracheids were present. 
The apogamous outgrowth shown by Fic. 14 occurred as a 
lobe on the margin of a very irregular and distinctly notched 
prothallium, in the region of the sinus. From only a few cells in 
wid:h the apogamous outgrowth developed into an elongated 
prothallus-like structure, thickened in the center and branched 
at its apex. One of these branches was narrow and several 
