258 МК. В. Ss ADAMSON ON THE COMPARATIVE ANATOMY 
V. sp. (? Balfouriana, Hook. f.). 
This species was cultivated under the name V. chathamica, but it is quite 
different both in form and structure from the plants of that name in Cockayne's 
herbarium. Externally it is very like V. Traversi, but the leaves are 
slightly larger and not so thick. It seems nearest to Г. Dalfouriana *. 
Glandular and other hairs occur in the furrow over the midrib. The stomata 
are not so much protected as in V. Travers. The mesophyll consists of 
elongated palisade-like cells arranged in vertical rows with considerable inter- 
spaces. At the tip is a peculiar form of hydathode termed by Haberlandt 
a * Koópfehenhydatode" 1. At the tip of the leaf а narrow thin-walled cell 
projects beyond the level of cavities of the epidermal cells, reaching the outer 
Tissue of leaf-apex of V. sp.: under hydathode (4). x 180. 
surface of the general cuticle in a shallow basin-shaped hollow. Covering 
this hollow and connecting with the thin-walied cell mentioned is a large 
eushion-shaped cell which projects above the surface of the leaf. This 
cushion-shaped cell has protoplasmic content; its outer wall is slightly 
thickened and eutieularized. This hydathode differs from those described by 
Haberlandt in having a head consisting of only one cell. 
V. pimeleoides, Hook. f. 
The leaves are shorter and thicker, concave above. The outer epidermal 
walls are much thickened and the stomata оп both surfaces are sunk. The 
mesophyll is like that of the preceding species, but with the intercellular 
spaces much less developed. The midrib is embedded ; its bundle does not 
end in a hydathode. V. pimeleoides forms the connecting-link with the next 
group. 
Grove D. 
Externally the leaves of the species in this group are like those of Group C, 
but are thicker and much more xerophilous, usually concave above and often 
* Bot. Mag. t. 7556. + Haberlandt (1894) (1909). 
