390 Groom . — On the leaves of L at hr aea Squamaria 
by several layers of cells, the same peculiar system of cuti- 
cularized canals is often visible. When, however, the bundles 
dwindle to a line of tracheides separated from the dome- 
shaped glands by only one layer of parenchyma, I sometimes 
failed to detect cuticularization of the walls bounding the 
intercellular spaces. Near the margin of the leaf the tracheides 
are dilated and ampullate, and end against small parenchy- 
matous cells which connect them with the basal gland-cells. 
These parenchyma-cells are always separated by considerable 
intercellular spaces: so that these marginal glands are built 
on precisely the same physiological plan as those in Lathraea, 
though not in the same histological manner. 
Rhinanthus Crista-galli. 
As the excessively rapid discharge of water from the leaves 
of Pedicularis rendered it impossible to localize the exact 
source of the excretion of water, it seemed advisable to select 
a plant whose leaves possessed fewer dome-shaped glands. 
On this account I found Rhinanthus Crista-galli a suitable 
subject for investigation. 
Each leaf is thick with indented margins which are slightly - 
recurved towards the lower face. The nerves correspond 
with depressions on the upper face. The secondary nerves 
run from the midrib to the sinuses of the marginal indenta- 
tions. The dome-shaped glands are very much less numerous 
than in the two preceding plants ; they are limited to the 
lower face of the leaf, and only lie over the finest nerves, 
especially near the margin. The shortly-stalked capitate 
glands, distributed in the same manner, are very much more 
numerous, but they also occur in considerably smaller num- 
bers in the furrows denoting the nerves, on the upper face 
of the leaf. Acuminate hairs are present on both faces of 
the leaf and on the margins. The stomata are numerous 
on the lower face, and a few occur on the upper face of 
the leaf. 
Excretion of water by the Leaves . Plants rooted in grass- 
