IC THE CAUSES OF FLUCTUATIOliS IK TUliGESCE^'CE
to the action of anicstlietics, and the next one shows that oxcossively low temperatures
procUico the same effect.
Expcnmcnt XL—A. largo leaf o£ Kalanchoe, weighing 28-75 grammes, was put into a
metal bos and buried in a mixture of pounded ico and salt. On being removed after
an interval of an hour and a quarter it was found to bo rigidly frozen, but without
visible exudation or cliange of colour. It was now sot in a hennotically closed chamber,
and very soon began to sweat -visibly. Oa the following day it had acquired a yellowish
tint and was quite flaccid and moist. The weight was now only 24'16 grammes, corresponding
to a loss of i-odc.c. of fluid, and on the following day was only 22-55
grammes, giving a total loss of 31-5 per cent, on the original weight. The only
difference presented by the phenomena in this case as compared with those occui-ring in
cases of anaesthesia was the primary absence of exudation ; but this is readily accounted
for if it be taken into account that any liquid entering the intercellular spaces in the
initial stages of the experiment must have been frozen as it approached the surface of
the leaf, and so have plugged the stomatic orifices.
It is not, however, merely anaasthetics and excessive elevation or depression of
temperature which produce such results, for essentially similar ones occur in cases where
the tissues are exposed to strong acid or alkaline vapours, to immersion in solutions of
corrosive sublimate, or to the influence of electrical currents or discharges.
I have not personally tried any experiments on the action of electrical currents on
vegetable tissues, but the accounts which are furnished by Becquerel* regarding the
results of his investigations of the subject leave no doubt that they also give rise to a
loss of turgescence. Ile found that, in the case of milky Euphorbias, treatment of the
shoots "with electrical discharges was followed by a suppression of the discharge of latex
on subsequent incision, a phenomenon which can only have been due to loss of turgescence
in the milk tubes. When leaves of Begonia discolor, which are red on one face
and green on the other, were subjected to electrical currents, the red face became
sensibly green and the green one red, due to escape of the red fluid from the interior
of the cells normally containing it and its diffusion throughout the intercellular spaces
of the tissue. He was at first inclined to explain the escapc of liquid from the cells
as due to rupture of the walls of the latter under the influence of the electricity; but,
finding that there was no microscopical evidence of rupture, he ultimately came to
the conclusion that the phenomenon was due to alterations in the nature of the
The following experiments illustrate the effects produced by exposure of the tissues
to poisonous vapours and solutions:—
Experiment XII.—A leaf of Kalanchoe, weighing 10'03 grammes, was sot in a carbonic
acid chamber. The first result which manifested itself was a certain amount of intensification
of the green colour of the tissue, but the surface gi-adually became moist, and
within a quarter of an hour actual exudation of drops of liquid had occurred. On tho
following day the leaf was of a dull, ochreous brown colour and weighed only 8-9
grammes. It was returned to the chamber, and twenty-four hours later was almost
" Des Foi'cc$ Phy si CO-Chimique 9." Paris, 1876.
17
loss of 19'6 per cent, on
IN THE MOTOR OflGAXS OP LEAVES.
completely flaccid and weighed 8'06 gi-ammes, equivalent to i
the original weight and to an exudation of l'97c.c. of liquid.
Experiinejit XIII.—A leaf of Kalanchoe, weighing 27'93 grammes, was set in a
carbonic acid chamber. Visible exudation began within tho course of an hour and
advanced rapidly, accompanied by collapse of the leaf. The reddish colouring along
the margins of the lobes was, primarily at all events, intensified, and the rest of the
surfaco gradually became yellowish. On the following day the loaf was moist, flaccid,
and weighed only 24-61 grammes, indicating a loss of 11-8 per cent.
Experiment XIV.—k leaf of Kalanchoe, weighing 13-64 grammes, was suspended
over water in a carbonic acid chamber. It remained in tho chamber for forty-eight
hours, and at the close of that period was flaccid, of a yellowish olive colour-, and
weighed only 11-54 grammes, indicating a loss of 15-3 per cent, of total weight.
Experiment XV.—A leaf of Kalanchoe, weighing 33"22 grammes, was set in a
hydrochloric acid chamber. Visible exudation and brightening of the red colour at the
margins of the lobes soon appeared. On the following day it was flaccid and of a dull
yellowish olive colour, and weighed only 28-51 grammes.
Experiment XVI.—A leaf of Kalanchoe, weighing 18'12 grammes, was set in a
hydrochloric acid chamber. Visible exudation was present within a quarter of an hour.
Twenty-four hours later it was very moist, quite flaccid, of a yellowish olive colom-, and
weighed only 15-02 gi-ammes.
Experiment XVII.—A leaf of Kalanchoe, weighing 14-62 grammes, was placed in
a nitric acid chamber. On the follo^'ing day it was of a yellowish olive colour with
the edges of the lobes strong pink. It was not so moist or flaccid as a leaf treated
at the same time in a hydrochloric acid chambcr, but showed a loss of 15-5 per cent,
in weight.
Experiment XVIII.—k leaf of Kalanchoe, weighing 13-08 grammes, was set in a
nitric acid chamber. Visible exudation occurrcd within two houi-s, and on the following
day it \\'as perfectly flaccid, of a dull olive with pinkish along the margins of the
lobes, and weighed only 10-23 grammes, having lost 21-7 per cent, in total weight.
- Experiment XIX.—A leaf of Kalanchoe, weighing 14-13 gi-ammes, was set in an
osinic acid chambcr. Blackening of the 'surface rapidly set in, and on the following day
It was coal-black and covered by large isolated drops of inky fluid. It was not,
however, flaccid, and only sliowed a loss of 7-2 per cent, in weight, whilst a leaf
which had been exposed simultaneously in a nitric acid chamber showed one of 21'7
per cent. Twenty-four hours later it was ^^till nearly rigid, but had discharged a
considerable additional amount of black liquid and only weighed 12-51 grammes.
Experiment XX.—A leaf of Kalan'Iioe, weighing 15-17 grammes, was set in an
osmic acid chamber. It began rapidly to blacken at the edges, and at the close of
two hours tho discolom'ation hnd spread inwards considerably, and one or two small
drops of black exudation had appeared on tlie surfaco of all the lobes save one. There
ANN. HOY. BOT. GAKD. CALC\;ITA Vor., V I.