quite close beneath the gland, the tentacle generally becomes
inflected. I tried this experiment repeatedly, as I was much surprised
at the fact, for all other parts of the pedicels are insensible to any
stimulus. These headless tentacles after a time re-expand; but I shall
return to this subject. On the other hand, I occasionally succeeded in
crushing a gland between a pair of pincers, but this caused no
inflection. In this latter case the tentacles seem paralysed, as
likewise follows from the action of too strong solutions of certain
salts, and by too great heat, whilst weaker solutions of the same salts
and a more gentle heat cause movement. We shall also see in future
chapters that various other fluids, some [page 37] vapours, and oxygen
(after the plant has been for some time excluded from its action), all
induce inflection, and this likewise results from an induced galvanic
current.*
* My son Francis, guided by the observations of Dr. Burdon Sanderson on
Dionaea, finds that if two needles are inserted into the blade of a
leaf of Drosera, the tentacles do not move; but that if similar needles
in connection with the secondary coil of a Du Bois inductive apparatus
are inserted, the tentacles curve inwards in the course of a few
minutes. My son hopes soon to publish an account of his observations.
[page 38]
CHAPTER III.
AGGREGATION OF THE PROTOPLASM WITHIN THE CELLS OF THE TENTACLES.
Nature of the contents of the cells before aggregation Various causes
which excite aggregation The process commences within the glands and
travels down the tentacles Description of the aggregated masses and of
their spontaneous movements Currents of protoplasm along the walls of
the cells Action of carbonate of ammonia The granules in the protoplasm
which flows along the walls coalesce with the central masses Minuteness
of the quantity of carbonate of ammonia causing aggregation Action of
other salts of ammonia Of other substances, organic fluids, &c. Of
water Of heat Redissolution of the aggregated masses Proximate causes
of the aggregation of the protoplasm Summary and concluding
33