On the Phenomena of Propagation of Movement in
Mimosa pudica.

BY

SURGEON-MAJOR D. D. CUNNINGHAM, M.B.,

SPECIAL ASSISTANT TO SANITARY COMMISSIONER WITH THE GOVT. OF INDIA.

     In one of the most recent English works on Vegetable Physiology¹the
author expresses himself as follows in regard to the question of the propagation
of movements inMimosa pudica and similar plants:—

     "It appears from these considerations that the theory which regards the transmission
of a stimulus as a mere propagation of a disturbance of hydrostatic equilibrium is not
satisfactorily established. The theory is altogether too purely mechanical to account for
so remarkable a phenomenon in a living organism, and we must endeavour to establish for
it some other explanation which, while borne out at least as fully by the facts, will be more
in harmony with our conceptions of the organisation of living beings."

     An attempt is next made to show that such an explanation is to be found
in the continuity of the protoplasm throughout masses of vegetable tissue
forming tracks for the propagation of irritation from one organ to another.

     The object of the following pages is to show that this theory is by no
means as fully borne out by the facts as that for which it is substituted, and
that there is a great mass of phenomena which, however they may conflict with
current conceptions regarding organisation, clearly indicate that fluctuations in
fluid tension, acting along with structural peculiarities of different masses of tissue,
are the principal, if not the sole, cause to which propagation of movement must
be ascribed. Details of such phenomena will be found in the tables showing
the results of a very extensive series of experiments on the movements in
Mimosa pudica, and they appear to me to justify the following theses:—

I. The degree to which propagation of movement occurs runs parallel with
the degree to which facilities for the extension of fluctuations in the
fluid tension of the tissues are present.

II. The direction in which propagation of movement occurs is in many
cases that in which the occurrence of fluctuations in the fluid
tension of the tissues can be shown to occur, whilst it cannot be
accounted for as the result of protoplasmic conduction.

III. The order of events in instances of propagation of movement is in

¹Lectures on the Physiology of Plants. By Sydney Howard Vines, M.A., D.Sc., F.R.S., Cambridge,
at the University Press, 1886.

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