Steil. — Apogamy in Ncphrodium hirlipes , Hk. 113 
antheridia were produced in all cases except Trichomancs Kraussii , in 
which they aborted before reaching maturity. Woronin holds that the 
Pellaea and Nothochlaena species have become apogamous on account of 
the xerophytic conditions under which they live. It is assumed that 
such an environment, being unfavourable for fertilization, may have led to 
the development of apogamy. 
Yamanouchi (1908 c) reported the occurrence of apogamy in Nephro- 
dinm molle , Desv., the prothallia of which had been watered from below 
and kept in direct sunlight. He had shown that fertilization and sporo- 
genesis normally occur in this fern, and hence was certain that the apo- 
gamy which he observed had been induced by the cultural conditions. 
The apogamous sporophyte is described as having the gametophytic 
number of chromosomes, namely from sixty-four to sixty-six. It is to 
be regretted that none of the sporophytes thus produced were grown to 
maturity. A study of sporogenesis, if spores were formed at all, would 
be of especial interest. According to Yamanouchi, the apogamous sporo- 
phyte began its development in a comparatively short period after the 
prothallium assumed the heart-shaped form and when the archegonia are 
ordinarily produced. Hence a long period of time does not appear to 
be necessary to induce apogamy, as seemed to be the case in Lang’s 
experiments. 
Miss Black (1909) has duplicated so far as possible with the same 
species the cultural conditions used by Yamanouchi for inducing apogamy 
in N ephrodium molle. She also grew the prothallia of Dryopteris stipularis 
under the same conditions. Although the prothallia of both species were 
watered from below and kept in strong light, they developed to a large size 
and produced sex-organs. At no time were sporophytes produced in any 
of the cultures so treated. 
Mottier (1915) also attempted to show the effect of dry cultural 
conditions and strong light on the development of apogamous embryos. 
He grew the prothallia of both the species which Miss Black had used, 
as well as those of Onoclea Struthiopteris. Mottier also was unable 
to induce the appearance of a single apogamous sporophyte. On the basis 
of this work and of a study of the normally produced embryo of Nephro- 
dium molle , Mottier questions whether Yamanouchi was actually dealing 
with an apogamously produced embryo. 
Heilbronn (1910) found among the prothallia of a culture of Asplenium 
Ruta-muraria prothallia which he identified as those of Cystopteris fragilis . 
The latter were isolated, and their further development was studied. 
It was observed that in the stronger illumination of summer, embryos were 
produced apogamously as outgrowths both of the vegetative cells of the 
prothallium and of the sex-organs. Later in the season, when the illumina- 
tion was weaker, the projections like those which during the summer formed 
I 
