132 CUKXIXGIÎAM FLÜCIUATI0N3 TURGESCENCE.
The eTeiiiHg depression of almosplierio humidity and thi
rntory loss must, of course, tend to facilitate the occurvi
conneoted with fluctuations in turgescence, but at the nnme tin
able reduction in distal leterag'i, which must more or less eqr
with increased transfdrfttory loss, ao that on the whole the ot
he fairly credited to decreased retentive power
property in the cell-sap. That this is, at all evi
which normally presents itself in tHe evening is,
themselves dniing periods of prolonged and more
praotically saturated and transpiratory
LHSpie
it tends
[librate th.
the
s, the
nt increased facility for
diffusion of rapid movements
to give rise to n vory coiisideritahility
connected
i r r i t a b i l i t y " may
Limiuished osmotio
itabiJity"
increased i
Jilvinar tissues iQoident on
aain determinant of tiie rit
loreover, demonstrated by the phenomena wliioh present
,T less continuous rainfall, when both soil and air are
rily reduced to a minimum. Under suoh oirenmstances
R'ill be found that, whilst amputation of the tips of terminal pinnules during the day, and whilst the
leaves are iu maximal diurnal positiou, is followed only by vvry limited and imperfect movements of
piunular elevation, purely confined to the injured pinnii and unuccompanied by any movements of petiolnr
depression save in tlie case of leaves which are heavily loaded with adherent water, a similar injury in
the evening and when the leaves have already completely assumed the nocturnal position is constantly
followed by the deepest petiolar depression quite apart from tKo presence of any extrinsic distal loading.
'J'he effects of simple rQechani<>a! "stimulation" also vary very conspicuously in degree at different times
if day. The haves of seedling plants iu tlie morning and early f.;r
1 to influence of direct suushine and its attendant excess
trail spirato
id exceedingly irresponsive to mechanical impulses, whilst in the
, are in their maximal nocturnal position, the primary petioles
eadily undergo the deepest depression on contact,
i previous especiments we have been dealing with cases in which
elevated
and piuE
but very
I n Í
I long as they are not
ry loss, are very highly
ig, when tlie pinnules
n very highly elevated,
ave evidence of increase
• i r r i t a b i l i t y " a.incid.nt with decreased assimilatory activity connected with the removal of solar
stimulation ; but parallel phenomena present themselves in oases in which protoplasmic activity is depressed,
not by the'absence of normal stimuli, but in consequence of exposure to the iuilueuce of ana-sthetics.
I n order to the proper comprehension and interpretation of suoh phenomena it is necessary to have some
acquaintance with the eSects which follow exposure to simple desiccated atmospheres and simple exposure
to anxsthetic vapours, as the evidences of increased " i r r i t a b i l i t y " connected with the Utter manifest
themselves most clearly in oases of sudden exposure to a desiccated atmosphere containing -i'apour
of chloroform. The data -wliich follow are accordingly derived from tln-ee distinct ' sets of
experiments. In the first of these plants were exposed to the atmosphere of a hermetically sealed
chamber containing a vessel of pure sulphuric acid; in the second they wcie exposed to a humid
atmosphere containing chloroform vapour; in the third they were exposed to the desiccated atmosphere
of a eliamher containing both chloroform and pure sulphnrio acid.
ExrEHiMEST l Y . — A iiot-plant, in a pot which had been waxed and lufed as if for experiments on
transpirutury loss, was enclosed iu a hermetically sealed chamber contiiining a ves.'el of pure sulpliuiic
acid and esnosed to diffused sunlight. The leaves passed into tiie maximal diurnal position, but were
extremely "irritable," movements attending the slightest mechanical disturbance, and the momentary
appiicntion of flame to the tips of terminal pinnules being followed, not merely by complete movements
through.iut the injured leaf, but by propagation of movements to sevei'al other leaves. The soil in the
jrfaces was sufKcient, to permit
,ivo transpiratory luss; but tlie
rery readily induced under the
es of the motor organs, or any
e tissues incident on injury,
cally sealed chamber containing a
slowly and gi-adually assumed
itly moist, and the proportion of root-surfaces to foliar
inteuance of the maximal diurnal position in spite of very t
1 was a very unstable one, and consequently movements wer(
)f any factors either favouring increased filtration iti the tis
Lncrease in transpiratory loss, or abnormal escape of liquid from
?ERiMEST Y.—A pot-plaut was set within a common hermetic
loluding a plug of cotton-wool soaied iu chloroform. The leave
t less completely, and after some time death of the entire plant occurred,
of the nocturanl position was clearly simply owing to the action of the
of the n
equilibri!
influence
sudden i
Exi
vessel
lal position
sumptio
anfflsthetio in depressing assimilatory activity ; for the plant was througliout exposed to abundant
diffused sunlight, and the atmosphere of tho chamber must very soon have become more or less
saturated owing to transpiration i'rom the kaves and evaporation from the m-ist soil in the open pot.
"F
h
APPr.îînioE3.
bai=al and terminili portions of the solitar of I
mtial p.irtio s enclosed i ; the
small pot-plant wo
vapour of oldorofor
leaves of the cent
Expekimkkt YL—The
carefully protected and the c
A graiual assumption of the nocturnal positiou followed by death occurred i
exposed portion of the axis, wliich itself ultimately died and bccame brown, whilst ihe leaves on tlie basal
and distal protected portions mpiiily resumed tlie diurnal position, ti-om whicli they had departed iu connection
with the initial disturbance to which they had necessarily been subjected, and retained it unaltered
afrer the central portion of the axis and its leaves had been completely killed. On the following day,
and alter the central part of the axis had been dead for many hours, the leaves on the basal and distal
portions were in normol diurnal position, and the application of heat to tho base of the axis was
followed, not merely by movements in the lea
prnpngation of movements to those which were
Y I I . - A plant in a coi m open pot v
a vessel of strong sulphuric acid, so i
loss. After the expiry of half an hour,
of cotton-wool saturated with chlorofori
of the nootnmal position occurred wiihin
slc>w, progressive ch«racter.
ExrEBiMENT V I I I . - A plant in r
•atory los», and whilst tlie lei
s situated to that side of tho dead central area, but by
situated beyond it.
sed within a sealed chamber coofaining
I of itinuoup, active tro
. maximal diuriial positi(
;h timber. A com pi p to f
iadinc to it being of an
s to secure the o
ind when the leaves were i
1 was introduced into the
two hours, the movements I
ispiratory
n, . ri>.g
ssumption
insensibly
carefully waxed nnd luted pot, so as to secure m
ere in full diui-nnl position, was suddenly introduced .
chamber containing vessels of botli strong sulphuric b
inderwent sudden,
pinnules were one
lal
ral leí
I considerable interval had
the pinnai o£ all the leaves
ith its lea
from the chamber, ond, when all th(
introduced into the chamber. After
abruptly elevatfd througliout almost a
petiole occurred iu any case.
EsPEmHEKT IX.—A plant in a luted pot, and '
suddenly introduced into a chamber like that employed
of about half a minute, rapid spreading elevation
elevation was, however, incompletely carried out. N<
primary petioles.
Expekimrnt S . — a pot-plont, luted
introduced into a sealed chamber contai
whatever occurred; but merely very slow, i
remained within the chamber fcr a short
recovered their normal diurnal position,
chloroform and of pi
of pinnules, and,
id and chloroform. After a hi
•apid elevation. The pot was n
more in maximal diurnal position, was again
dapsed, numerous pinnules became
hut no depression of the primary
i in maximal diuvnal position, was
in the previous experiment. After an interval
Df the pinnules set in in many pinn®. The
depression whatever occurred in any of the
the usual fashion for experiments on transpiration, was
Ig vessels of chloroform and of water. No rapid action
msibly progressive elevation of the pinnules. After it had
ne it was removed and, after the pinnules hod completely
ntroduced into a sealed chamber containing vessels of
sulphuric ai^id. Bapid movements .of elevation presently occurred iu a number
n interval, the primary petiole of the uppermost leaf, the pinnules of which
condition of permanent elevation, underwent rapid
Expkrimf.nt X I , — a pot-plant, luted as usual and with
adlurent drops of rain, was introduced info a sealed chamber
of sulphuric acid. After an interval of fifty seconds some f
slowly and partially elevated, and after a further interval of two
of another leaf acted in a similar fashion. Elsewhere only slaw,
occurred.
The results of this
I.—Exposure
its leaves abundantly bedecked wi
containing vessels of ohlorofonn ni
innules in one loaf became rektive
minntes all the pinnules of one pirn
insensib'y progressive pinnular elevatii
ries of esperiments clearly demonstrate the following facts:—
the influence of anaasthetics under certain circumstances is attended by the
occurrence of movements of precisely the same character as those which are ordinorily
regarded as depending on stimulation and aoiive contraction of the protoplasts
of the motor organs.
II.—The rate at which movements occur under the influence of exposure to the vapour of
chloroform varies with the degree to which facilities for the rapid transpiratory
removal of water from the tissues are present.