A Study of Apogamy in Nephrodiutn hirtipes, Hk. 
BY 
W. N. STEIL, 
University of Wisconsin, Madison, Wisconsin , U.S.A. 
With Plates V-VII. 
Introduction. 
T HE first reported observation of a sporophyte tissue element in the cells 
of a fern gametophyte was made by Leszcyc-Suminski (1848), who 
found tracheides near the apical notch of the prothallium of Pteris sul- 
cata, L. 
Wigand (1849) described a cylindrical or conical process produced 
as an outgrowth from the apical notch of the fern prothallium, instances of 
this sort being found in several cultures. According to his description, the 
embryo begins its development on the ventral side of the prothallium and 
at the posterior portion of the process. Since there can be no certainty 
regarding the purity of his cultures, the peculiar developments described 
cannot be referred to any particular species. There can be no doubt, how- 
ever, from his descriptions (l.c., pp. 106, 107) and figures (Figs. 25-9) that 
he studied embryos of apogamous origin. 
Mercklin (1850) found cells in the prothallium of Pteris sulcata like 
those observed by Leszczyc-Suminski. Mercklin also figured (l.c., PI. VII, 
Fig. 6) a prothallium and a young embryo of Nothochlaena Eckloniana. 
Mercklin’s figure, although somewhat diagrammatic, suggests that the 
embryo had been apogamously produced. Over a half-century later 
Woronin (1907) found apogamy in the same species. 
Farlow (1874) discovered apogamy in Pteris cretica albo-lineata , and 
was first to recognize clearly the nature of an apogamous embryo as 
distinguished from one resulting from fertilization. He described the 
origin of the embryo as an asexual outgrowth from the prothallium. When 
the embryo is about to begin its development, the portion of the prothallium 
posterior to the apical notch becomes pale, and tracheides appear in the 
nearly colourless region. A process, similar to that described by Wigand, 
develops from the apical notch. The embryo is now produced on the 
ventral surface of the prothallium posterior to the apical region. The leaf 
[Annals of Botany, Vol. XXXIII. No. CXXIX. January, 1919.] 
