5 
of Splachnum luteum . 
to that in the tissues of the vascular plants h This is rendered 
more striking by a comparison with the parenchyma of the 
lower surface in the same region, where the cells are much 
elongated in a direction parallel to the surface, and with very 
much larger intercellular spaces. The distal region of the apo- 
physis shows that the cells of both upper and lower surfaces 
have undergone a considerable lengthening in the direction 
parallel to the surfaces, but that the upper as compared with the 
lower has still a resemblance to palisade-tissue (Figs, ii, 12). 
The epidermis covering the apophysis is of a pale brown 
tint resembling most closely the epidermis of the leaf of 
a typical Phanerogam, the external wall of the cells being 
the thickest (Figs. 10, 12). On the upper surface of the part 
of the apophysis which is nearer the sporangium the epi- 
dermal cells are flattened ; as the periphery is approached 
they become cubical, and in young specimens are even 
columnar in form (Fig. 11). On the under surface the same 
state of things is found, the epidermal cells nearest the seta 
being very much flattened. There is distinct cuticularisation 
of the epidermal cell-walls, and a distinct cuticle is present 
on the external surface, as is shown by the action of Schulze’s 
solution. The outer walls of the epidermis are thicker on the 
upper side of the apophysis than on the under, and a cuticle 
is also present on the under surface of the apophysis. Cuti- 
cularisation does not extend completely through the walls of 
the epidermal cells ; the inner layers of cell-wall becoming 
bright blue with Schulze’s solution, thus showing that those 
layers consist of pure cellulose. A plate of cuticularised 
membrane extends down the middle of the radial cell-walls 
from the external cuticularised layer. As far as I could deter- 
mine, there were in the epidermal cells only a very few small 
chloroplastids present, in which starch is sometimes to be 
found, but only in small quantities. 
1 Haberlandt {Joe. cit .) also makes a comparison between the chlorophyll- 
containing tissue of the sporophyte of the Mosses and the palisade-tissue of true 
leaves ; but in none of the forms which he investigated is this structure as striking 
as it is in S. luteum. 
