4 8 
William J. Hodgetts. 
where the single connecting cell was attached; these scars were 
frequently seen on old stems, just above the insertion of the leaves. 
Any one of these thalloid protonemata can, of course, give rise 
to a leafy shoot on becoming detached from the parent stem. 
They attach themselves to the substratum by numerous brown 
rhizoids, which grow out from the narrow basal part. Secondary 
thalloid protonemata may arise as outgrowths from any part of the 
primary one; they usually arise, however, from the narrow basal 
end, growing out into the air as leafy expansions. We thus 
frequently find a tuft of green thalloid protonemata arising from a 
mass of brown rhizoids, which fix them to the soil. 
In Fig. 1, c and d show how the leafy stem arises from the 
protonema. In c a young bud has arisen at the base of a thalloid 
protonema; in d the bud has become elongated into a leafy axis. 
Leafy stems (and even stems with the terminal gemmiferous cup) 
can very frequently be found to be connected with thalloid proto¬ 
nemata at their base. Dixon 1 remarks that the “frondiform leaves'’ 
(i.e., thalloid protonemata or “protonemal leaves”) of T. pellucida 
“ disappear before the development of the stem ”; but a careful 
examination of almost any tuft of this moss will show some quite 
mature stems connected at their base with one or more “frondiform 
leaves.” They appear to nourish the young leafy axis, and may 
flourish for a considerable time after the stem has become well 
established. It is interesting to compare this with the other British 
species of Tetraphidaceae, namely Tetradontium Brownianum. This 
moss is almost stemless, its vegetative part consisting merely of a 
tuft of narrowly clavate “ frondiform leaves,” which may be some¬ 
what palmately branched at the apex, and amongst which the 
capsule is produced. 
Thus, besides the formation of numerous gemmae, by which the 
plant most frequently reproduces itself, T. pellucida has another, 
apparently uncommon, method of vegetative reproduction in the 
formation of leafy protonemata from the stem. It should be noticed, 
however, that plants which resort to this method of reproduction 
have been precluded from forming gemmae by the apex of their stem 
having been killed. Thalloid protonemata were never seen in the 
axils of the leaves of plants which had a terminal gemmiferous cup, 
nor of plants the stems of which had a living apex. 
Although in Fig. 1 a, the oldest thalloid protonema is drawn 
nearest the stem-apex, and the youngest nearest the base of the 
1 Dixon, “ Students’ Handbook of British Mosses,” 2nd Ed., p. 31. 
