^ ^ THE CAUSES OP F L A C T U A T I O N S IN T U R G E S C E N CE
ontù-cly unaffcctcd. That this is the cixso is shoM-n by the results of the following
expcrimeuts :—
Experiment I.—A leaf of Cassia suviairans Tx-as taken and its three distal pairs of
pinnai, together ivitli the corresponding portioQ of the rachis, wore securely lutod into a
test tube through a perforated and paraffined cork. The loaf was now set with the freshly
di-idcd lower extremity iu a vessel of M'ater, and llie entii-e apparatiis was introduced
into a large chloroform-chaiuber. Three hours later the parts of the leaf wHch were
exposed to the chloroform were quite flaccid, whilst the protected ones remained quite
green and turgid. The leaf was now removed fi-om the chloroform-chamber, and, the test
tube having been taken off, it was set in a simple moist chamber. On the following day
the portion which had been protected remained as before, with the racliis and
pinnae quite green and the latter in a state of full expansion, whilst the -whoh of
the rest of the leaf was of a brownisii olive colour and witli the pinnoe absolutely
flaccid.
Experiment JI.—A mature leaf of Cassia sumairam, with tho four distal pairs of
pinnaî and tlie corresponding jjortion of the rachis protected as in the previous
experiment, Avas set in a chloroform-chamber. At the close of three hours the exposed
portions were of a dull olive green colour and the pinnoe were very limp, whilst the
protected portions remained iu their original state. The loaf was now removed from
tho chamber, tho test tube being taken off, and was set in the open laboratory. On
the following day the portions which liad been exposed to the chloroform were of
a dull brownish olive, whilst all those which had been protected were quite fresh,
gi-ecn, and turgid. Iu a check lefif. which had been set iu the open laboratory witliout
water at the same time as the previous one, the piunoe were all dry and extremely
and rigidly depressed, so that it could not have been auy conditions of atmospheric
humidity which caused iho persistent greenness and turgidity of the protected portions
of the other. •
Experiment HI.—A leaf of Cassia sumatrana was taken, and the lower extremity
of the petiole was freshly divided subaqueously. Botli the basal and the distal portions
were now protected and the central portion was exposed to the action of chloroform for
some time. It was then removed and set in a moist chanibcr \yith the base of the
petiole luted into a bottle of water. On the following day the portion of tlie rachis
which ]jad been exposed to the ciiloroform was of a brownish colour and studded with
numerous drops of brown exudation, and the corresponding pinniB were brown, moist,
and flaccid; while the protected portions both basal and distal W&TQ quite green and
turgid and showed no traces of exudation.
Experiment IV.—A young green shoot of Cassia sumatrana bearing several leaves
was set in a bottle of water. The submerged end of tiie axis was now freshly cut,
so as to present a fresh absorptive surface, and the mouth of the bottle was carefully
luted. The apparatus was next set for a short time in a chloroform-chamber, and was
then removed and transferred to a common hermetically closed one. Visible exudation of
fluid presently occurred on the axis, rachiscs and petioles, and the pinnje first partially
assumed tho normal nocturnal position and then became quite flaccid ,and olive-brown
LIN T H E L I O T O E OLTÓAXS Ü F L E A V E S, I I
On the following day tho di-ops of fluid on the axis, rachises and petioles had assumed
a dark-brown coloui-, wiiich fact, as well as their entire absence from the sui-faces of
the pinnaj, showed that they were duo to exudation and not to sm-face-condensation.
Experiment V.—A shoot of Cassia sumatrana sot as in the previous experiment. In
a little over an hour visible exudation • had set in in the axis, rachises and petioles. At
this time there was no evidence of change of colour in the pinniü, bat they luid in great
part assumed their nocturnal positions of depression, convergence, and rotation according
to theii- respective ages, and that the plumomenon was not a simple one of general
flaccidity was shoAvn by the fact that in those leaves which, in mtroducing tho shoot
into the chamber, had been reversed, the pinnre, in place of being depressed below the
plane of the petiole, were elevated above it. Ultimately general fiaccidity and discolouration
occurrod, accompanied by COUSJDÍCUOUS exudation of drops of fluid on the axis and
rachises. Tho discolouration and exudation were sharply limited to those portions of
the specimen which had been directly exposed to the chloroform, the base of the axis
and the lower pai-t of the lowest petiole which had been protected by the luting remaining
quite gt-een, turgid, and devoid of any da-ops of fluid.
The phenomenon of free exudation on the surface of the axis in such experiments
presents itself only so long ns iho latter is yonng and has not yet become elothod by
any corky strata; in other words, so long as there aro stomatio orifices present permitting
oí the escape of fluid from the dense tissue beneath. So long as it does occar it is
of com-sc, simply a parallel to the general exadation occnmng from the loaves of 'plants
like Kdanehoe antler similar conditions. Tho fact of general loss of tm'ge.scence throngh".
out the leayos is, in the absence of soluble colouring materials and with the presence of
an erfensivo iuteroellalar area, indicated only by the flaccitUty and saturation of the
tissues; and the special value of this set of experiments lies in the demorrstration aflorded
by some of them that the capacities of the water-conducting system remain entirely
unaffected under conditions abolishing the turgescence of tissues in wliich the active
retention of fluid is dependent on the continuous exercise of protoplasmic function and
that the action of anajstherics like cHoroform is a .purely localised one, confincd solely to
the protoplasts which are directly exposed to it, and not leading to any propagation of
the depression or abolition of functional activity from the protoplasts so situated to
those which are protected from the direct action of tho ono3sthetic.
The phenomena attending tho action of aiiicsthetics on vegetable tissues are not
peculiar; but, save in certain exceptional case-s to bo presently alluded to, occur
whenever protoplasmic function is depressed or abolished in tissues whose turgosconce is
dependent on tlie presence of living protoplasm. This comes out very clearly from the
results of the following experiments:—
Experiment I.—A leaf of Kalanchoe, weighing 12-9 grannues, was immersod foiabout
one minute in water at a temperat\ire of 69°C., and tlien gently wiped dry and
placed in a hermetically closed chamber. It soon began to exude drops of liquid, which
within three hom-s had accumulated in large pools, the colour of tho leaf having at the
same time begun to show a yellowish tint. It now weighed 11 '2 grammes, corresponding
to a loss of l-lc.c. of fluid. Discharge continued to occur, and on the following mornin^
tho weight was only 104 grammes, indicating a loss of 2-bc.c. of fluid and 1S-.5 per
cent, of total weight.
ANN. ROY. BOT. GARD. CALCUTTA VÜI,. V I.