and of some allied Scroph u lariaceae. 397 
one vegetative season, but have to endure the hardships 
of a winter, the dangers of saturation of the soil, and the 
percolative movements of the water in the soil. In con- 
firmation of this view the following facts appear in reference 
to Lathraea and the parasitic Scrophulariaceae previously 
described in this paper: — ( j) the dome-shaped glands are 
frequently confined to the recurved part of the leaf; (2) the 
glands are always very numerous in the strongly recurved 
types of leaves ; (3) considering any particular plant, the 
relative number of glands on the leaf-surface is proportionate 
to the curvature of the leaf ; (4) the curvature is strongest 
in the subterranean leaves. Even when the curvature is not 
more marked in the subterranean scales, chambers lined by 
glands are formed by the appropriate arrangement of the 
scales, at any rate in some plants ( Bartsia ). 
Additional functions of the scale-leaves of Lathraea. I can 
add nothing to the information given by previous observers 
with reference to the capitate hairs. The leaves excrete 
a certain amount of chalk. Their fleshy mesophyll contains 
a great quantity of large grains of starch. 
Conclusion . The pocket-like leaves of Lathraea are excre- 
tory organs and carbohydrate-reservoirs. Their concavity of 
form is assumed for the purpose of protecting the subter- 
ranean excretory mechanism ; their succulence is associated 
with the necessity for providing house-room for the rich 
stores of reserve starch. 
This research was conducted in the Botanical Laboratory 
of the University of Oxford. 
E e 2 
