DEVELOPMENT OF THE SPOROGONIUM IN THE MOSSES. 269 
mature seta every, or nearly every, cell of the parenchymatous 
sheath was connected with one or two of the cells of the cortex 
(fig. 28). 
Examination of the cell-walls with the ordinary reagents showed 
that the cuticle of the epidermis contains cutin, and is covered 
by a distinct cuticle, which is isolated, but is not dissolved, by 
strong chromic acid; the cortical sterome was altered in some 
undetermined way, since Schulze’s solution gave a slight purplish 
tint with only slight staining; neither aniline chloride, hydro- 
chloric acid, nor phloroglucin produced any coloration*; the 
parenchymatous cells of the cortex showed a more distinct blue 
coloration with Schulze’s solution. The cell-walls of the lepto- 
phloém were only coloured very slightly dull light blue by 
Schulze’s solution; aniline chloride, hydrochloric acid, and phlo- 
roglucin produced no coloration ; the cell-walls of the leptoxylem 
with Schulze’s solution stained a deep bright blue. 
The above holds good for the species of Polytrichum and 
Pogonatum which I have examined, and for the species of 
Mosses from other Orders which I have been able to examine, 
e. g. Funaria hygrometrica, Linn., Dicranum scoparium, Hedw., 
Mnium hornum, Linn., &c. 
PoLytTRIcHUM. . 
Several species of this genus have been used in this investi ga- 
tion, namely P. formosum, Hedw., P. juniperinum, Hedw., P. pili- 
ferum, Schreb., and P. commune, Linn. ; so that all that is stated 
below in regard to this genus holds good for all those species 
except where the contrary appears. Several species of the genus 
Pogonatum have also been examined, but they do not differ mate- 
rially from Atrichum and Polytrichum, being intermediate between 
these two genera. 
The colour of the seta in the species of Polytrichum is due to 
the presence of red and brown colouring-matter in the cell-walls. 
The structure of the seta in Polytrichum is fundamentally the 
same in this genus as in Atrichum. The variations from the 
type of Atrichum may be in part due to difference of size. The 
* Since writing the above, I have gone into the question of the constitution 
of the cell-walls in the Mosses more carefully, and, although the investigations 
are not yet complete, I am able to say that the cortical sterome is lignified and, 
Perhaps, corky. The investigation is rendered peculiarly difficult owing to the 
Presence of various colouring-matters in the cell-wall. 
