On Evil in Small Doses 
of cork on injured stems, and the great and unusual 
flow of resin whenever certain Coniferee are wounded, 
show a distinct effort of the plant which must surely be 
the result of a stimulation of its life-processes. When 
the balsam fir (Abies balsamea) is attacked by a rust- 
fungus, it also responds by increased resin flow and by 
forming a larger number of bud-scales than usual.” 
Nor is it only the flowering plants which show the 
power of dealing adequately with an emergency of this 
kind.* Polyporus and Coprinus, when their sclerotia 
are injured, are able to form a new brown protecting 
envelope. 
All these and many other instances show that evil in 
small doses is often a strong stimulus, which somehow 
calls into existence adequate remedies, 
It is only by its strange power of secreting some 
appropriate substance that vegetable protoplasm can 
deal with such situations, 
Of this power there are many remarkable instances. 
In the life of a palm leaf, for instance, there comes a 
time when the old and dead leaf is a nuisance rather 
than a help to the tree. Then one finds remarkable 
modifications going on near the base of the leaf-stalk. 
First a continuous group of cells, across its base and at 
an angle of 45 degrees to it, deposit cork in their walls ; 
then, beyond these, the walls of the neighbouring cells 
degenerate into some jelly-like modification of cellulose. 
When wet weather comes, this gelatinous material swells 
so that the cells become spherical, and in consequence 
the great leaf drops gently and softly away, leaving a 
well-corked scar by which no fungus can enter.” 
The whole of this complex procedure has been 
arranged simply by the secretion of cork and the change 
of cellulose into its gelatinous variety in one part of the 
stalk ! 
332 
