252 МВ, В. S. ADAMSON ON THE COMPARATIVE ANATOMY 
Details of the Leaf-anatomy of the Species. 
GROUP А, 
The leaves are large and elongated. А constant feature in this group is 
that the central bundle ends in a hydathode ; at the tip of the leaf the 
vascular bundle ends in а mass of small-celled parenchyma beneath а water- 
stoma (fig. 5). The size оЁ the intereellular space behind the pore varies in 
different cases. 
Fic. 5. 
Longitudinal median section of leaf-tip of V. catarracte, showing the termination 
of the bundle ina hydathode. х 500, 
V. salicifolia, Forst. 
Leaves sessile, lanceolate-acuminate, З х 1 inches, with slightly ‘notched 
margins. 
Along the upper side of the margin and above and below the midrib are 
rows of stiff cuticularized hairs, each consisting of 2-3 cells. Stomata occur 
on both sides, numerous below but few above. Those of the upper side have 
a characteristic structure in section; the guard-cells are small and the 
adjacent epidermal cells are “scooped out” so that the guard-cell rests on 
them ; the guard-cells have small cuticular expansions. 
The mesophyll shows the usual differentiation into palisade and spongy 
tissues ; the latter consists of small rounded cells with small intercellular 
spaces between ; between the palisade and the upper epidermis is a single 
