STEIL: SOME NEW CASES OF APOGAMY IN FERNS 105 
5. Either root or leaf or both of these organs may develop on 
the dorsal side of the prothallium. As a rule, however, they are 
produced on the ventral side. 
6. While the embryo is produced as a rule posterior to the 
apical notch, it may be formed on a cylindrical or conical “ pro- 
cess’’ and in some instances on the lobes of the prothallium. 
7. Several apogamous embryos may be formed on a single 
prothallium. 
8. As in non-apogamous species, secondary prothallia are 
readily produced, and these form embryos like those of the ordi- 
nary prothallia. 
g. The “‘light’’ area present on the prothallium of some of the 
apogamous species is rendered more conspicuous in cultures main- 
tained in weak light. The conical or cylindrical “process’’ in- 
" creases considerably in length when the prothallia are grown under 
these conditions. As a result of weak illumination, the embryo is 
frequently produced as a direct outgrowth of the apical region of 
the prothallium. 
10. By growing the prothallia of Osmunda regalis in strong 
light and preventing fertilization for a year and a half, no embryos 
were produced apogamously. 
11. An investigation extending over a period of six years has 
resulted in the discovery of apogamy in a large number of ferns. 
The conclusion that apogamy is of frequent occurrence in the 
genera Pellaea, Pteris, and Aspidium, is justified on the basis of 
the many cases so far found in these genera. 
I wish to thank Professor C. E. Allen for suggestions and criti- 
cisms received during the progress of the foregoing investigation. 
UNIVERSITY OF WISCONSIN, 
MapIsoN, WISCONSIN 
LITERATURE CITED 
Allen, R. F. (1911). Studies in spermatogenesis and apogamy in 
ferns. Trans. Wisconsin Acad. 17: I-56. pl. I-6. 
Bary, A. de. (1878). Ueber apogame Farne und die Erscheinung 
der Apogamie im Allgemeinen. Bot. Zeit. 36: 449-487. pl. 14. 
Berggren, S. (1888). Ueber Apogamie des Prothalliums von Noto- 
chlaena. Bot. Centralblatt 35: 183-184. f. 1-3. 
