Developments of the Oophyte in Trichomanes . 279 
vidual alone. I take this opportunity of acknowledging my 
obligation to Prof. Dickson for handing over to me material for 
an investigation in which he had already interested himself. 
Work was begun on the Edinburgh plant, and the results 
acquired from it are briefly stated in the Annals of Botany, 
Vol. I. No. II. Since that note was written I have had the 
advantage of making comparison with the magnificent speci- 
mens growing in Kew, and it is found that not only do they 
show similar peculiarities to those of the Edinburgh plants, but 
even further abnormalities which will be described below. The 
conclusion to be drawn is, that, since in three different collec- 
tions plants of this species show similar peculiarities, these are 
to be regarded as frequent, or even constant characters. 
Aposporons Growths . — The sori of those specimens which 
I have examined frequently produce normal sporangia with 
mature spores ; but the great majority of the prothalli 
which I have observed were produced, not by germination of 
spores, but by peculiar aposporous growths, which arise in 
remarkable profusion from such old fronds as have fallen to 
the ground, or even from the tips of pinnae of fronds, which 
still retain their normal position. 
As to the mode of formation, point of origin, and structure 
of the prothalloid organs, which are produced by direct vege- 
tative outgrowth from the frond, there is great irregularity. 
It may be stated at once that the resulting prothalli differ 
from those of Tr.pyxidiferum in the fact that, though they are 
often protonemal in form, yet flattened expansions, one layer 
of cells in thickness, are of common occurrence (Fig. 25), while 
a succession of these may be connected by protonemal fila- 
ments so as to form a very complicated and irregular whole 
(Fig. 24). This may be compared with the description and 
figures given by Mettenius for Tr. incisum \ 
These irregular prothalli may originate directly from the 
frond in various ways : thus, single cells of the apex of the 
pinna (Fig. 26), or of its margin (Fig. 27), may grow out into 
1 1 . c. Taf. v. Fig. 1 and p. 492. 
