ASPLENIUM EBENOIDES 489 
fertilize the archegonia on the archegonial section before that sec- 
tion could regenerate antheridia of its own. 
It is obvious that in seeking to discover the origin of A. eden- 
aides the removal of organs of A. platyneuron or C. rhizophyllus is 
only of use in so far as it may facilitate cross-fertilization, for A. 
ebenoides, while it combines characteristics of these two ferns and 
hence might be produced by their cross-fertilization, is so distinct 
from either that it could not possibly be produced by the cross- 
fertilization of either. For the same reason it could not be pro- 
duced by the asexual growth of either. Therefore if a plant of 
A. ebenoides should spring from prothalli of A. platyneuron and 
C. rhizophyllus that had been planted together and pure cultures 
had been insured, that plant must be considered proof that A. eben- 
oidestis a hybrid between A. platyneuron and C. rhizophyllus. 
SOLVY 
Fic, 2. 
In order to insure pure cultures, in my experiments the pro- 
thalli have been raised on sterilized earth in new flower-pots and 
kept under glass. Lack of success during several years in crossing 
A. platyneuron and C. rhizophyllus has not been caused by prothalli 
of these ferns failing to produce a hybrid when planted together, 
but by the difficulty in getting prothalli of both ferns in proper con- 
dition at the same time in order to plant them together. Almost 
4S soon as that was overcome results followed. 
; In the winter of IQOO—IQOI spores of these two ferns sown 
iN separate flower-pots developed prothalli in large numbers. 
During February and March archegonial sections were cut from 
the prothalli of C. rhizophyllus, planted in a third pot, and a whole 
Prothallus of 4. platyneuron planted close against each section. In 
4 fourth pot archegonial sections of A. platyneuron were planted 
