104 STEIL: SOME NEW CASES OF APOGAMY IN FERNS 
duced in large numbers as a result of fertilization, Hence it is 
certain that the cultural conditions which were maintained ren- 
dered fertilization impossible. The prothallia grown under favor- 
able conditions were smaller, but produced numerous sex organs 
and embryos only as a result of fertilization. 
Since the prothallia for the cultural work were found growing 
under plants of Osmunda regalis, and since no other osmundas 
were growing in the immediate vicinity, it could hardly be assumed 
that the prothallia could be referred to any other species. Never- 
theless, spores of O. regalis were collected and sown in the Wardian 
case, and in every respect the prothallia grown corresponded to 
those brought from the field. 
The experimental work with Osmunda regalis was of especial 
interest, since Leitgeb (1885) reported in this species the occa- 
sional occurrence of apogamy. No one, however, has confirmed 
the observation. Although Lang (1898), Yamanouchi (1908), 
Pace (1913), and Nagai (1914) believed that apogamy might be 
brought about by cultural conditions, Miss Black (1909) and 
Mottier (1915) were unable to produce a single apogamous embryo 
by cultural conditions. 
SUMMARY 
1. The prothallia of a number of species of ferns in which 
apogamy was discovered were grown under cultural conditions 
favorable for the development of sex-organs and embryos in non- 
apogamous species. 
2. The prothallia of all the apogamous ferns become heart- 
shaped before the formation of the embryo. Antheridia are pro- 
duced on the prothallia of all apogamous forms, but archegonia 
are formed on the prothallia of only a few forms. 
3. The embryo usually appears as a compact region of cells 
posterior to the apical notch and on the ventral side of the pro- 
thallium. In a number of species tracheids are visible among the 
prothallial cells in the pale portion of the gametophyte. 
4. First to make its appearance is the apical cell of the leaf, 
then that of the root, and later that of the stem. A foot has not, 
so far, been observed to develop in connection with the apogamous 
embryos. 
