IIO 
Steil. — Apogamy in Nephr odium hirtipes, Hk. 
appears first, then the root, and later the stem. A foot is never formed. 
Between the cells of the gametophyte and those of the apogamous embryo 
there is no sharp line of distinction. The vascular system of the embryo is 
intimately connected with vessels in the prothallium. These characters 
described by Farlow for Pteris cretica have been found by other investigators 
in a number of apogamous ferns. In the same year Abbot (1874) reported 
apogamy in an unidentified fern. 
De Bary (1878) extended Farlow’s observations on Pteris cretica and 
also tested a large number of other species to determine the extent of 
apogamy in ferns. He found it to occur in Aspidium falcatum and 
A. Filix-mas var. cristata. The development of the embryo in both these 
species is similar to that described by Farlow for Pteris cretica. 
Sadebeck (1879) reported apogamy in Todea africana. Leitgeb 
(1885) reported it as occurring occasionally in Osmunda regalis and Cerato- 
pteris thalictroides. His observations on the two latter species have, 
however, never been confirmed. Stange (1887) discovered apogamy in 
Doodya caudata , Todea pellucid a, and T. rivularis. Berggren (-1888) de- 
scribed it in Nothochlaena distans. 
The development of the apogamously produced embryos of Doodya 
caudata was investigated by Heim (1896). Since archegonia and antheridia 
appear to develop to maturity in this species, Heim believed that fertilization 
may also occur. Archegonial and antheridial ‘projections’ are developed 
on the prothallia, and these projections produce the apogamous embryos. 
As many as thirty projections may be formed on a single prothallium, 
but only a few embryos produced will survive. 
Bower (1888) discovered apogamy in Trichomanes alatum. Although 
spores are ordinarily formed in this species, apospory commonly occurs. 
The prothallia thus developed give rise to the apogamous embryos. 
Lang (1898) induced apogamy in the following species of ferns, the 
prothallia of which were grown under special cultural conditions for a period 
of two and a half years : S colop endr him vulgare , Sw., vars. ramulossi- 
simum , Woll., and marginale , Nephrodium dilatatum , Desv., var. cristatum 
gracile , A! ephrodium Or copter is, Desv., var. coronans , Barnes, Aspidium 
aculeatum , Sw., var. midtijidum , Woll., A. angulare , Willd., vars. folio sum 
midtifiduni and acutifolium multifidum , A. frondosum , Lowe, A. thyrium , 
Mett., var. nipponicum and var. cristatum, A. Filix-foemiua , Bernh., vars. 
percristatum , Cousens, cruciato-cristatum and coronatum, Lowe, and Poly- 
podium vtdgare , L., var. grandiceps , Fox. By watering the cultures from 
below and keeping them in strong light, Lang believed that apogamy was 
induced. He was inclined to think that the high temperature under which 
the prothallia were grown may have been a factor in inducing the appear- 
ance of the sporophytic structures, although he believed that the prevention 
of fertilization was the most important condition. 
