81 
more closely to the other cells, with perhaps less tendency to 
alobate form, but like them they consist of more or less irregular, 
rounded, paren- 
chymatous cells. 
The lobes men- 
tioned above cha- 
racterize more 
particularly the 
central and lower 
cells of the meso- 
phyll, and are 
seen most dis- 
tinctly in the 
transverse and 
longitudinal sec- 
tion; in surface 
section the cells 
of the mesophyll 
are irregular, but 
no lobes can be 
seen. In surface 
section the inter- 
cellular spaces, 
which never attain 
any considerable 
size, are sharply 
defined and shew 
transparent in 
contrast with the 
brownish colour 
(in spirit-material) 
of the cells of 
the mesophyll; 
they are smaller 
XXXVI. 
Fig. 1. Pirola grandiflora. 
1, Leaf in transverse section. 2, The epidermis of the lower surface. 
3, Hydathode. 2, The epidermis of the upper surface. 5, Stoma. 
6, Horizontal section through the mesophyll which answers to the 
palisade-layer. 7, Horizontal section through the lower cells of 
the mesophyll. The peculiar intercellular spaces should be noted. 
(Hab. several places in Greenland; Z is from Upernivik). (H.E. P.) 
The letters which accompany the figures indicate the same every- 
where: — Zp, epidermis; Zi, the epidermis of the lower surface: 
Es, the epidermis of the upper surface; Chl, chlorophyll grain; pa, 
palisade-tissue; Jnt, intercellular space. The upper and lower 
epidermis seen from the surface are drawn always with the same 
magnification in regard to each species. 
6 
