18 Brown: APOGAMY IN PHEGOPTERIS POLYPODIOIDES 
time stimulated the development of apogamous embryos in 
this species. 
Woronin (’07) believes dryness to have been the cause of 
apogamy in the cultures of Pellaea and Notholaena with which 
she worked. By growing the prothallia of Pellaea flavens in 
poor light or on poor soil she was able to secure modifications 
in apogamous outgrowths, which showed transitions between 
gametophytes and sporophytes as varied as those described by 
ang. 
Yamanouchi (’08), in his study of Nephrodium molle, found 
that when conditions for fertilization were supplied this species 
reproduced normally, but that if the cultures were placed in 
strong light and watered from below fertilization was prevented 
and apogamous outgrowths were formed instead. 
Outgrowths of an apogamous nature were described by Miss 
Pace (’10) as occurring on some unidentified prothallia which 
she kept well-watered in bright light. 
Heilbronn (’10), finding that dryness was not the cause of 
apogamy in the forms he studied, suggested that summer rather 
than winter cultures were more likely to become apogamous. 
But his investigations with different qualities and intensities of 
light, in moist cultures and at a high temperature, did not 
verify these conclusions. 
Schlumberger (’11) found that by decreasing the moisture 
for old prothallia of Woodsia ilvensis, whose vitality had become 
lowered by the growth of algae and fungi in the cultures, the 
production of apogamous outgrowths was induced. He believes 
the observed enlargement of the apices of these apogamous 
outgrowths to be analogous to that described for Anogramma 
chaerophylla by Goebel (’97), who considered their development 
to be an adjustment on the part of the plant to the unfavorable 
environmental conditions caused by dryness. 
Allen (’11) found apogamous sporophytes occurring on pro- 
thallia of Aspidium falcatum which had been grown in pots of 
red clay surrounded by sphagnum or moist sand, and kept either 
in a Wardian case or under bell Jars for five, six, and in one case 
eleven months. These prothallia were not watered from above, 
the water in the sphagnum or sand keeping the clay uniformly 
moist, 
