Steil. — Apogamy in N ep hr odium hirtipes , Hk. 1 1 7 
in detail, but, so far as I have observed, it seems normal in every respect. 
The antherozoids are actively motile. 
Secondary prothallia were readily induced, and these resembled in all 
essential respects the primary prothallia, producing, like them, apogamous 
sporophytes. I have also found that in some other apogamous species, 
including Pellaea atropurpurea , Pteris cretica albo-lineata , and Pteris sulcata , 
secondary prothallia produce apogamously sporophytes. 
Numerous attempts were made to induce apospory in Nephr odium 
hirtipes by methods which have been described by different investigators to 
bring about aposporous development of the gametophyte in other ferns, such 
as placing the leaves of young sporophytes in contact with the soil, attach- 
ing to the soil leaves and fronds of older plants, placing portions of leaves 
on moist soil or sphagnum, and growing prothallia-bearing young embryos 
in weak light. So far, only the last method has been successful to a very 
limited degree. Occasionally when prothallia with very young embryos 
were placed in subdued light, the apical region of the prothallium, frequently 
almost colourless grew forward into a long cylindrical or conical process, and 
on the new portion it was observed that after the primary leaf had begun 
its development as a direct outgrowth of the prothallium, its proximal 
portion, instead of forming a lamina typical in form and structure, became 
branched and gradually prothalloid. A root, so far as I could determine, 
was usually absent in such cases. Fig. 22, Plate V, represents a good 
specimen of this kind observed in the cultures. The petiole (p) was cylin- 
drical and contained a well-developed vascular bundle (v), shown only in 
part in the photograph. No stomata were found on any portion of the 
sporophytic growth. The cells (c) in the flattened portion of the structure 
next to the terminal part of the petiole were columnar and presented 
a regular arrangement. There was a gradual change in the form of these 
cells towards the apical region (a) which was already differentiated. A 
filamentous portion (/), consisting of a single row of cells, had been produced 
from the prothalloid part of the outgrowth. Later an embryo was observed 
to begin its development directly behind the apical region (a). Whether or 
not such a development of a gametophyte from a sporophyte of this nature 
is to be called apospory is a question of definition. 
The Sporophyte of N ephrodium hirtipes. 
Development of the Embryo. The embryo originates from cells posterior 
to the apical notch of the prothallium and on its ventral side. A light- 
coloured region frequently appears either in the notch or at some distance 
behind it (Figs. 4, 5, 6, 10, n, Pl. V). It is in this light-coloured region that 
the embryo is usually formed. The cells of this region usually contain 
numerous colourless plastids, but few chloroplasts as compared with the 
