25 
and Helminthostachys zeylanica . 
distributed throughout the humus but were most numerous 
close to the rhizome of the Polypodinni , often being situated 
between its ramenta. The following account is based on the 
examination of this material. 
The first stages in the germination of the spore of this plant 
have been described by Campbell 1 . After a year and a half 
the largest prothalli consisted of but three cells and were still 
partially enclosed in the exospore. Chlorophyll had not been 
developed in them. 
The smallest prothalli found in nature, one of which is 
represented in PI. I, Fig. I, are, as the side view shows, 
narrow below and widen out rapidly above. The gently 
convex upper surface is smooth, while the sides are covered 
with short unicellular hairs. The basal region is light brown, 
the upper part white. Regarding the colour of the prothalli 
it may be said generally that the younger regions are white, 
the older parts being more or less discoloured. Viewed from 
above or below, the outline of the prothallus of this age is 
circular, and a comparison of the different aspects shows that 
it is radially symmetrical. This radial symmetry is retained 
in all the branches of the older prothalli. 
Sometimes the young prothallus continues its growth 
without branching, but as a rule branching occurs in prothalli 
which have reached the size of that just described. Usually 
two or three branches of equal size are developed (Figs. 2-4). 
These are connected by a region, which corresponds to the 
lower portion of the unbranched prothallus. The specimen in 
Fig. 2, in which the origin of two branches is visible, was 
attached to a fragment of tissue in the humus. That shown 
in Fig. 3 had evidently given rise to two branches, one of 
which has again branched. In Fig. 4 a prothallus with three 
branches is seen, and this is also the case in the older pro- 
thallus represented under a lower power in Fig. 5 - The first 
branches, as these figures show, have a slight upward direction. 
In larger prothalli the primary branches have in turn branched, 
sometimes in a horizontal, at other times in a vertical plane, 
1 Mosses and Ferns, p. 224. 
