90 
larized layer, and is sparingly covered with large peltate hairs. The 
lateral walls are almost polygonal. An inner membrane is often 
seen to have separated from the inner walls of the cells of the 
epidermis giving an impression that we are here dealing with 
an inner mucilaginous wall (Fig. 7). But such a structure | 
have not been able to demonstrate with any certainty. In a 
few cases I further observed that a similar structure was found 
in connection with the ‚upper margin of the cells. It is possible 
that the spaces thereby formed contain a fluid which serves 
as a protection against the danger of 
L 
Es excessive transpiration. In some cases 
I observed starch — or properly 
speaking chlorophyll grains with starch 
— in the upper epidermal cells. The 
lower epidermis is strongly papillose, 
each cell-cavity terminating in a pa- 
Fig. 7. Rhododendron 
lapponicum. pilla. These papillæ have at their 
Mor; Membranes. 7Z Tumen. TR Dex a cuticleswhich is slightly aomen 
figure shews indications of the 
mucilaginous walls which occur in with prickles. The stomata are con- 
ts species (Greeniand). (-"*) Aned to the lower surface of the leaf, 
and, as is well-known from Warmine’s description (l. c. p. 112 
and Fig.8 in Om Gronlands Vegetation), they all occur 
beneath the peltate hairs with which the whole of the lower 
surface is thickly covered. Upon the inner side of the guard- 
cells and upon the nearest adjacent cells a cuticularized outer 
layer may be seen. 
The palisade-cells occur in 5 to 6 layers, and are small 
(at most about 50) and diminish in height towards the interior; 
they constitute about one-third the thickness of the leaf. The 
spongy parenchyma consists of non-branching cells, united into 
lamellae that stand at right angles to the longitudinal axis of 
the leaf. Very large intercellular spaces occur between the 
lamella. Below the vascular bundles may be seen indications 
of aqueous-tissue. 
