and of some allied S crop hula riaceae. 389 
glands contains solid calcium carbonate in small quantities. 
The external walls of the gland are marked with straight 
striations, which descend from the cap-cells to the basal cell 
as far as the general epidermis or to the point of contact 
of a contiguous gland. The cuticle is thickest on the wall of 
the stalk-cell. The transverse walls bounding the stalk-cell 
are thin, and consist of pure cellulose. The basal cell has 
conspicuous elongated pits on its lateral walls where they 
impinge on the basal cell of an adjoining gland. The fine 
vascular bundles have well-developed tracheides, and run 
close beneath the dome-shaped glands. When the bundle 
still possesses phloem (which therefore lies between the 
tracheides from the glands), a unique histological provision 
exists apparently for the purpose of directing the flow of 
water from the tracheides to the neighbouring glands. The 
cells of the nerve-parenchyma-sheath lying on the side away 
from the glands are closely set together without intercellular 
spaces ; but tracing them up to the sides of the bundle towards 
the glands, they are continuous with series of thin- walled 
parenchymatous cells which end finally under the glands. 
Distinct intercellular spaces occur amongst these connecting 
cells. Where their walls connect them with their fellow-cells 
they consist of pure cellulose, but where the walls bound the 
intercellular spaces they are cuticularized. The result is that 
the nerve-parenchyma-cells in contact with the tracheides 
communicate with the basal cells of the glands by thin-walled 
cells whose intercellular spaces form a network completely 
lined with cuticle. This arrangement, I suggest, enables water 
to flow, even under pressure, from the tracheides to the distant 
glands without being forced into the intercellular spaces. 
Where the intercellular spaces reach the lower wall of a basal 
cell, the cuticularization spreads over that region of the basal 
wall. Hence the lower wall of a basal cell is cuticularized 
in patches which correspond to the intercellular spaces ; but 
consists of pure cellulose where it touches the subjacent 
parenchyma. Even when the vascular bundles have lost their 
phloem, the tracheides being still separated from the glands 
