20 Brown: APOGAMY IN PHEGOPTERIS POLYPODIOIDES 
nutrient solutions. About six months later, cases of apogamy 
were observed in cultures on Prantl’s solution from which the 
NH.NO; had been omitted. In view of the small number of 
such cases, however, it was thought best to repeat the experi- 
ments, and also to make cultures from spores of the same species 
whose sporophytes had grown under normal environmental 
conditions. In this way it was hoped that it might be possible, 
by a comparison of the results obtained, to determine whether 
apogamy was characteristic of this species, and, if so, under what 
environmental conditions this condition was induced. 
For this purpose, during the following summer (1916), fresh 
spores were obtained from the same plant at Ithaca and also 
from wild plants at Brooklin, Maine (the latter through the 
courtesy of Dr. A. H. Graves). Cultures of these were started 
early in October on Prantl’s and Knop’s full nutrient solutions; 
on modifications of Prantl’s solution from which NH,NOs,, 
K.SQO,, NaCl, CaSO., MgSO,, NasPO,, and both NaCl and 
NasPO,, respectively, were omitted; and on Knop’s solution 
minus the Ca(NO,).. In preparing the cultures, about 25 cc. of 
the nutrient medium was poured into a small glass dish, a drop 
of a I per cent solution of ferric chloride added, and the spores 
sown upon the surface of the solution. The dishes were covered 
with loose-fitting glass tops. Two series of cultures were pre- 
pared from each of the two lots of spores, one of which was placed 
in the greenhouse in bright light, the other in the laboratory 
before an east window. The germinating prothallia, instead of 
being transferred at intervals to fresh solutions (as had been 
done the preceding year) were allowed to remain upon the origina] 
solution on which the spores were sown, and the increasingly 
unfavorable conditions of environment which thus resulted 
were further enhanced by a luxuriant growth of algae which 
developed in all the dishes. 
DEVELOPMENT OF THE PROTHALLIA 
Practically no difference was noted in the germination of 
the spores or in the early development of the prothallia from the 
two sources. Germination began in about one week after the 
spores were sown. The early growth and development of the 
prothallia was rapid in all the cultures, but later it varied accord- 
ing to the particular solution upon which they were growing. 
