CUKÎÎINGHAM ON FLUCTUA TI OK S IN TUEGESCEN'CE.
chamber the noctnmal position ^vns again resumed, and was once more replaced by tlie diurDal one or
reta™ to tlie chamber. Tho phenomena present iu this esperi.nont not only demonstrate tlie o.xtrenu
rapidity of traaspiratory loss and the acournoy of the balança whicli must be Maintained bet«-eeti
trauspiratory loss >md root-supply of water in order to the retention of a given position by the pinnulebut
also tl,at the nocturB.l positio.i ia one which coinoides with mi,>or decrees of tui'gsseei.ce in thè
motor organs, and not witli increased turgescence as afRrmed by Pfefîer.
The resvilts of sis experiments with regard to the actual amount of t:
under favourable eiroiimsLances were as follows
Exi-eh
twsuty-ioui
MENT II.—A plant with seven
hours.
ESI-eiumk:
3'-10 C.C. wate
EXI-eroie
EXPE.C1MEEx
i-IS II ime:
1-5 C.C. water
Tlie füUü-«
T I I L - A plant
• iu twenty-fiTs h
;t I V . - a plant •
T V . - A plant w
T Y I . - A plant i
iu four hours.
sperimcnt illustrates thi
itory loss taking place
^ and 222 pinnules yielded ¡2-31 C.C. of wnter iu
leaves and 579 pinnules and weigliiiig 4-32 grammes yielded
eighing 4-34 grammes yielded 6'40 C.C. water
ighing 2'03 grammes yielded 4-1 C.C. water ii
ith five leaves and 194 pinnules and weighinf
--- — results foUowi:
between trauspiratory loss and root-supply of water:—
ExptKiMDN-r "^11.—The protruding portions of the roots of ee
into tLe ground were cut off. In some of the plants the branches
a limited number of leaves; in others they were left intact. Thirty^i:
5 were in full diurnal position, whilst
Qediate between the
' diittnal
the position of the
mies i
8 the transpiratory surfaces had been ¡'educed coincidendy wiili
with intact branches the apparatus for absorption liad been
in forty-eight hours,
twontj'-four hours.
2 32 grammes yielded
disturbance of the normal balance
several pot-j'lants wiiich Ldd rooted
iro cut shoit, so as to leave only
hours later all the leaves on the
I the plants with intact brandies
id the nocturnal one. The only
the two sets of plauts is that in
plants with shortened br;
the planuses were iu a position iut
thing to account for the difference
tlie case of those with shortened bran,
the absorptive ones, whereas in those w
dimiuisheil, whilst that determining loss of wat
Tbe next experiment also illustrates the
supply and loss of water, only in it the abi
divided extremity of tlie axis in place oi' being
Exvekimekc YIU.—a detached shoot wi
• remained ^s before.
iffects attending disturbnnce of t t e equilibrium between
rptive surface wos an abn.irnial one, consisting of the
•adicular.
fixed upright, so that its lower extremity dipped into
inlight. At 11-23 A.M. the pinnules were all almost in
V carefully removed without in any way disturbing the
- - -- 'ess highly elevated. The wnter-vessel was now
a vessel of water and w.is exposed to diffused
full diurnal position- The wuter-vessel was n
shoot, and at 12-7 noon the pinnules were all
replaced and a freth absorptive surface provided by
and at 2-20 p.m. ilie pinnules had almost all regained
ibaquoous division of the lower end of the axis,
ll positio
The results in experiments like tlie two preceding ones are precisely parallel to those attend.n«.
exposure to Lot and dry air, but are induced, not by increased loss, but by diminished supplv of w.iter
Ju order to establish a tendency towards the assumption of the nocturnal position all that is nece«arv
13 that the pre-existent equilibrium between supply and loss of water should be disturbed in such a
Jashion as to cause the latter to undergo a rL-lative increase. Such relativ
> increase
the result of diminished supply or of inorea.sed loss, but in any case the
which it pioduces £
the same. In the case of normally rooted plants an excess of loss
oouseqnc
idifj- «ni l,niperatme ol the almo.pbere sucli a. fceqmiillj jmvails , t n H d , , , „ a d
the course noff ftlhlOe «offftttei-rnnnortoTn*, "''id h^ " ' " ..— .1--. . I . .
noctumal position frequenily i
activity. In the cftse of piaci
assumptiou of the nocturnal j.
of water even when conditioi
I n tho fcriuer cbs<
in tho latter it folli
I t is relative dimiuution in Iosa
undi imptio
" such ci rcu m stances
spite of the fullest solar stim.ilatiou
îxposed roots, or of detached shoots, a
of the
nilatory
diurnal
3 supply
niifests itself i
with partially
ition attt-nds i
isiderable di mit
D3 are unfavourable to the occurrence of excessive transpiratory loss,
if the normal diurnal pofition attends a diminution in transpiratory loss;
al of water-supply, conditions of transpiratory loss remaining unaltered,
in either case which determines the resumption of the normal diurnal
APPEKDICES. 129
position, and such diminution may be effected as the result eitl.er of absokta diminution in loss or of
absolute increase in supply. Hence norm ally.n.oted plants which have passed into tho nocturnal
condition dim-nally may be caused to resume the normal diurnal one by exposing them to conditions
implying either diminished transpimtion or increased root-supply: in other words, by exposing ihem to
a more humid atmosphere, or by adding water to the soil iu which they are rooted.
APPENDIX C.
THE IKFLCENCE OF VAEIATI0^^8 IN BEGBUiî OF ASSIMILATOHY ACTIVITY 0>' THK OCCUKKENCP
AND CHAlUOTEli OF THE M o m i E K T S OP THi) LEAVES UF mMOSA PUDICA.
a osmolic capacity
activity of assimilatory function comi
to undergo sudden movemeuts. Th.
excessive atmospheric ami telluric 1
1 the tissui
• play I
of the motor organs
they are exposed to full
atmosphere of a simjile
movements of the leave
is followed by the oc
determines the exii
the filtrat
nidity
IJie existence of turgescence, aud iu
e escape of liquid incident on the
propeity in the cell-sap must fi
ud contequently the occurrence of
hence factors, which are q
in osmotic
filtration, a
the tissue;
fluctuations
it has und
liquid from
Of tissue, I
is a factor i
nomally impl:
iolar stimulati
ilphurio-noid chamber is o
leaves, exposure ia a chamber
e occuirence of rapid piiinulur
^-hen it acts al
ncidence of oth
ence of sudden
)y fluctuations
3 degree of ossl
. eTident that any
effects modified nccording a
afiecting turgescence. The
cence which makes for the
0 play
oected with variations in the
intrinsic factors ailectiug the liability of tho leaves
'irritability'' of plants e.xpns.d to conditions implying
inspicuously much greater after sundi.wn than whilst
whilst the sudden exposure of a plant to the arid
ily attended by slow and gradually progressive
containing both sulphuric acid and chloroform
movements. Osmotic capacity in the cell-sap
• has constantly to contend witli
the extended ceJl-walls. Any fall
elastic
ar the occurrence and rapidity of processes of
3id fluctuations iu the degree of tmgescence of
ipable of giving rise to rapid and considerable
tnrgescence whilst osmotic capacity is high, may well become efficient to do so when
3ne considerable decrease. The effect produced by any factor favouring the escape of
r of the cell-cavitios, and consequently making for din
.rily be modified by the degree of osmotic capacity
nutic
n tiirgesceuco
ill-sap which
—O-— — m Ilio cen-sau
iking for local retention of liquid. Consequently depression of assirailatory octiviiy
the sudden i
to the occuri
determined 1
tions in the
and i
liy comes into play to _
modifyiag the
ill be capabl
ismotic cnpaoity,
ne, but has also an important
r factors making for decreased turgesceE
movements. The ordinary periodio mo^'ei
!n turgescence in the tissues of the mot'
lilatory activity incident on the presence ^
other factors of fluctuations in turgescence
or in oppositi
1 determines '
üts of the leaves
organs connected
2 to, the ifluen,
produce :
milatory
of the c
at Bundo'
oo-operat:
of sohir
enee of
peimanence of t'
case is cleaily di
milatory
e occurrence of a fall in tu
xl position, and if another factor making fo
is evident that the effect which the latter
uto play at a time when the conditions of
they
>moval <.f sokr stimulati
issumpticn of the nootun
. . simultaneously with it, it
ikely to be greater than when it comes
ictivity, in place of favouring the assumption of the nocturnal positic
umal one. Hence, other things being alike, " i r r i t a b i l i t y " tends
n owing to the fuct that, at this time, any factor making for dec
m with a coini-ident fall iu aisimilati.ry activity which makes for tho
stimulation, however, not merely favours the occurrence of rapid m
)ther factors reolsiug for losses in turgescence in the motor org
:e tho position which has been assumed under the influence of the latte
aonstrated by the results of e.xperiments such as the followini? one :
ow, progressive
ttenfc to which
oi giving rise
are manifestly
ith fluotuasence
of solar stimulation,
st be liable to have their
r the 1 aiatenj
its
ased turgescence acts in
ime thing. The absence
remeuts under the influís,
but also affects the
That this is the
without
I . - A shoot
any special pi
of 2Imc
•ution to
(I pudica, bear:
avoid disturba
ag five leaves, was detached from a plant at
ce of the leaves, all of which, os is usloI under