and of some allied Scrophulariaceae . 387 
Pedicularis palustris. 
Inasmuch as this plant lives in damp, even marshy, spots, 
it seemed probable that it would possess a water-excreting 
mechanism. Its much-lobed leaves have their margins re- 
curved downwards. On the lower face of the leaf very 
numerous dome-shaped glands lie in furrows ; over the fine 
nerves, especially near the margins, the glands are so numerous 
and large in some spots as to be in lateral contact to the 
exclusion of general epidermis. The vascular bundles of 
the leaf end in fine branches running close to the epidermis 
of the lower face, and therefore very near to dome-shaped 
glands. These fine nerves are separated from the upper 
epidermis by the well-developed palisade-parenchyma. The 
shortly-stalked capitate glands are exceedingly rare on the 
lower epidermis, but long-stalked hairs occur along the 
courses of the grosser nerves on that face. Numerous stomata 
are present on the lower face. Dome- shaped glands and 
stomata are absent from the upper face of the leaf ; but a few 
capitate hairs occur above the courses of the nerves. 
Excretion of water from the leaves. When water was 
forced up shoots under a pressure of 1 inch of mercury 
(in addition to the atmospheric pressure), it sufficed to cause 
an instantaneous excretion of water from the leaves. But 
when a pressure of several inches of mercury was applied, 
the water gushed out from the leaves with great rapidity. 
All the young leaves were dripping with moisture, and water 
was to be seen falling from the leaf- tips and running down 
the surface of the stem in swift little streams, also welling up, 
fountain-like, from the leaf-axils. The very violence of the 
outpour rendered it impossible to localize its exact source. 
Inverting an excreting branch served to demonstrate that the 
young leaves were mainly responsible for the excretion of 
water, and that in the first experiment the stem merely 
conducted the water down the hairy lines on its surface, 
and thus caused the overflow at the leaf-axils. 
Histology of the dome-shaped glands. The excessive number 
