30 Brown: APOGAMY IN CAMPTOSORUS RHIZOPHYLLUS 
DIscUSSION 
Experimental data on induced apogamy would seem to indi- 
cate that bright light and insufficient moisture for fertilization 
were the controlling factors for the forms studied. In this partic- 
ular case an insufficient food supply seems of greater importance 
than these two factors for the following reasons. Apogamy was 
never observed in other cultures of this fern under the same light 
conditions where the nutrient solution was renewed frequently. 
The prothallium upon which the apogamous outgrowth occurred, 
while developing near the margin of the culture, was crowded by 
other prothallia and shaded by them. Sufficient moisture for 
fertilization was available, as the prothallia developed upon a liquid 
medium. Later, when the nutrient solution was renewed, thereby 
supplying sufficient nourishment, normal sporophytes developed 
in the culture, although conditions of light and moisture remained 
unchanged. The fact that the part of the apogamous outgrowth 
which was last to develop showed a reversion from a more or less 
complex structure several cells in thickness bearing tracheids to a 
simple prothallus-like one only one cell in thickness and branched 
indicates a lowered vitality of the outgrowth. Goebel considers a 
reversion to a juvenile form as being the result of unfavorable con- 
ditions. The unfavorable condition in this instance was doubtless 
an insufficient food supply. However, the effect of this factor in 
inducing apogamy will be discussed at a greater length in a future 
paper on induced apogamy in Phegopteris polypodioides Fée. 
Since only one case of apogamy was observed in the experi- 
mental cultures, it would seem that apogamy is of very rare occur- 
rence in Camptosorus and not easily induced. 
Explanation of plate 2 
Fic. 1. Prothallium showing apogamous outgrowth, X 120: P, prothallium; 
AO, apogamous outgrowth; Aj, Ag, archegonia; T, tracheids; Bi, Bo, branches; R, 
thizoids; L, lobe of prothallium. 
Fics. 2, 3. Surface view and median optical section view of the archegonium 
borne on the margin of the branch of the apogamous outgrowth, & 275: N, neck; 
C, canal; V, venter; E, egg; P, prothallium. 
