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Scientific Memoirs by

pudica is one of exceedingly unstable equilibrium dependent on the opposed
tendencies of different masses of tissue which tend in one case to establish the
nocturnal, in the other the diurnal, position of the various parts. The excessive
instability of the equilibrium is due, first, to the extreme fluid tension on which
it depends, and which is only maintained so long as there is a constant supply of
fresh fluid added to the tissues to make good the constant losses due to exces-
sive transudation, and, second, to the presence of structural differences in the
opposed tissues specially facilitating the occurrence of diminutions in fluid
tension in those which make for the diurnal position. The conditions are such
that very slight fluctuations in fluid tension are necessarily adapted to give
rise to extensive displacements of the various parts of the leaves, so that it
appears doubtful whether it be necessary in any case to assume the occurrence
of any active protoplasmic contraction in order to account for the motorial
phenomena.

       CALCUTTA;

   The 14th April 1887.