fected by it. It was a surprise to me to find that, with good
specimens, the effect was manifested in the course of so short a time as
a minute or so.

#Effect of chloroform.#--In studying the effect of chemical reagents in
plants, the method is precisely similar to that employed with nerve;
that is to say, where vapour of chloroform is used, it is blown into the
plant chamber. In cases of liquid reagents, they are applied on the
points of contact A and B and their close neighbourhood. The mode of
experiment was (1) to obtain a series of normal responses to uniform
stimuli, applied at regular intervals of time, say one minute, the
record being taken the while on a photographic plate. (2) Without
interrupting this procedure, the anaesthetic agent, vapour of chloroform,
was blown into the closed chamber containing the plant. It will be seen
how rapidly chloroform produces depression of response (fig. 44), and
how the effect grows with time. In these experiments with plants, the
same curious shifting of the zero line is sometimes noticed as in nerve
when subjected similarly to the action of reagents. This is a point of
minor importance, the essential point to be noticed being that the
responses are rapidly reduced.

[Illustration: FIG. 44.--EFFECT OF CHLOROFORM ON RESPONSES OF CARROT
Stimuli of 25 deg. vibration at intervals of one minute.]

#Effects of chloral and formalin.#--I give below (figs. 45, 46) two sets
of records, one for the reagent chloral and the other for formalin. The
reagents were applied in the form of a solution on the tissue at the two
leading contacts, and the contiguous surface. The rhythmic fluctuation
in the normal response shown in fig. 45 is interesting. The abrupt
decline, within a minute of the application of chloral, is also
extremely well marked.

[Illustration: FIG. 45.--ACTION OF CHLORAL HYDRATE ON THE RESPONSES OF
LEAF-STALK OF CAULIFLOWER
Vibration of 25 deg. at intervals of one minute.]

[Illustration: FIG. 46.--ACTION OF FORMALIN (RADISH)]

#Response unaffected by variation of resistance.#--In order to bring out
clearly the main phenomena, I have postponed till now the consideration
of a point of some difficulty. To determine the influence of a reagent
in modifying the excitability of the tissue, we rely upon its effect in
exalting or depressing the responsive E.M. variation. We read this
effect by means of galvanometric deflections. And if the resistance of
the circuit remain