296 Bower —Some Normal and Abnormal 
description of the mature gemmae correspond very closely to 
my own, but also those showing the development ; but whereas 
in Cramer’s specimens the gemmae appear to have been formed 
on mere filaments, in Tr. alatum they are rarely formed on 
filaments, and more commonly on the apex of flattened ex- 
pansions ; this is, however, an unimportant difference. It 
cannot be doubted that Mettenius’s figures 1 and those of 
Goebel 2 show early stages of development of similar gemmae. 
It may then be concluded that, though the formation of 
gemmae is not universally found in species of Trichomanes , 
it is at least a very general phenomenon. Referring to the 
process of oophytic budding generally, discoveries of recent 
years have shown that this mode of propagation is very widely 
spread among Ferns — a fact which tends further to establish 
the conclusion that the oophyte in Ferns is not merely a basis 
for insertion of the sexual organs, but is a generation leading 
an independent vegetative existence. 
Though the external form of the oophyte may be liable to 
considerable variation in different species of Trichomanes , the 
form of the sexual organs shows more decided uniformity, and 
on this account may be considered to supply more trustworthy 
ancestral characters. As figured by Mettenius, Cramer, and 
Goebel, the antheridia are stalked spherical bodies, which in the 
mature state consist of a peripheral layer of cells surrounding a 
mass of mother-cells of the spermatozoids (spermatocytes). In 
point of their mature structure a comparison may be drawn 
between these antheridia and those of some Liverworts, e.g. 
Radida or Trichocolea ; but the development of these, as de- 
scribed by Leitgeb, is dissimilar; there is also some similarity 
to the antheridium of Sphagnum. The study of the succession 
of the cell-divisions which lead to the mature condition presents 
some difficulties, owing partly to the density of the cell-contents 
in the young antheridium, partly to the fact that the antheridia 
of Tr. alatum are not fully developed in the normal manner. 
As above described, there are indications of an apical cell 
1 Taf. v. Figs. 8, 9. 
2 Taf, xii. Figs. 60, 61. 
