138 CÜKNINGHAM ON FLUCTUATIONS IN XUKGE3CJÍNCE.
necopted tlieory cf the iiidaition of suddenly executed movements wo\ild apparently domaiid, th.it
the vapour of cliloroforru becomes a stimulant to fanotional activity in a dry acinosplaere, whilst it
acta fts a depressunt in ti moist one? Surely it ia more rational to conoludo that in hoth cuses it acts
alike as a depressant of functional activity, but that the rate at wbioh indices to its action mniiifest
themselves in a reductiou of tui'gosceaoe varies with the extent to which facilities for the rniad
removal of water from the tissues are present.
IV.—Thai the nociuvnal position of the various parts of the leaves is one whiih is connected with
a degree of turgrscence in the motor or<jans greater than that tohick is present in connection
with the diurnal positinn*
lu order to domonstrate the grouadlessuess of this belief it is only necessary to call to mind the
plienomeiia which can be directly observed in the guard-cells iu connection witli the assumption of the
diurnal and nncturnal cnndition by the stigmatio oridces, together with the fact that tlie noclnrnal
Ijosition is assumed by the leaves of Mhnost pudioa under the influenoe of anrosthclies or of oonditious
implying excess iu transpiraiory loss io relation to root-supply of water.
A P P E N D I X E.
THE I.N-PLUENCE OF HYGROJIETRIC CONDITrO.vS ON THE DEGllEE OF
MawSA PUIJICA.
lUKIlABILITr" OP
Th e effect of hygrometria conditions in influencing tSie degree of liability to the occurrence of
rapid and extensively diffused movements iu ths leaves of Mimoxa ];tidica is illustrated by the following
experimental data. The experiments are ammgi'd in two distinct groups, A and B; tliose iueJudcd
under A illustrating the character and extension cf the movemouts following the incidence of so-called
stimulant" agencies under conditions of excessive atmos|iheric and telluric moisture; those under li
iliustraliiig the phenomena preseuting themselves under the inüuence of similar agencies when humidity
wns normal or depressed.
GROUP A,-HUMIDITY EXCESSIVE.
u.—Bcsidis following amputation of tips of terminal pinnules of distal pinnoe, or amputation
of tips of axes.
\.-~Elfects fulluwing ike amputation of the tips of pinnules.
E.xpeiiiment I . - J u n e 2-Srd. Temperniiire 77-5°F., atnioxphcnc hwnkhty 97 per cent. Itain had
fall-n éleadüy for some honn and viwt utill faWng heacHn ; etenjtlnng drcnched mUt wo(«¿vj'e.—Amputation
of the tips of terminal pinnules was followed by a pause, during which drops of exudation appeared at
the divided extremities of the mid-rib and the larger veins on the out surface. Elevation of the injured
pinnule, of its fellow, and of one or two adjacent pairs of pinnules followed slowly. Partial elevation
subsequently occurred in one or two others, but pinuular movements never extended along the entire
eoursfi of the injured pinnw.
EirBRiMi^aiT II.—July 19th. Tempcrainro 80®F., ahnospheric htmidili/ 97 ^íír cení. Cmiùnious
rnin had fallen during the previous nig'd and continued to fall gmUn at the time of experiment. Eceryúúng
iras drenched kíiH m')isture. The leave» icere in m:mmal diuriwi position and, in manij eases, icere heavily
loaded icii/i adherent drops of rni'n.—Amputation of the tips of terminal piniiult-s was followed by very
slow aud irrogular action in a certain number of pinnules. Frequently only two or three distal pinnules
* Sauns Vorlcsung.-n ; VorUsung, XXXII, s
AITEN DICES. lOi)
became elevated, and elevatkm of the injured pinnule was often delayed until visible exudation had
appeared ou the cut surface. In the case of heavily-loaded leaves depression of the primaiy petiole
usually occurred, the m<;vemeut immediately succeeding elevation of the injured pinnule, or of it and
its fellow.
Exveriment III.—July 20th. Temperature B^'Si'F., atmospheric humidify per cent. Heary rata
had fallen all night utid rain was siiU falling at the period of eo^periment. Efcrything icas drenched with
moidure. Amputation of t'le tips of terminal pinnules of leaves which were not loaded with adherent
drops of ruin wns followed only by imperfect elevation of a few distal pinnnlea in the injured pinnas.
No action whatever occurred even in the injured pinnule until after a pause, during wliicli drops of
exudation appealed ou tlie out surface.
ExpivRiment IV.—July 2óth. Temperature 78°F., alnmpherie hnmidil^y 94 per cent. Very heavy
rainfall had occurred shortly bfore and the shy was still covered icith clouds. Ei>"rything nm drenched icilh
niointure. The lear-es toere in maJiinial diurnal position and mani/ of them were heavily loidul with adhere vt
drops of j-ìk")ì.—Amputation of the tips of terminal pinnules was followed merely by slow and imperfect
action iu a few of the distal pairs oE pinnules in the iiijnred pinnaj, save iu tho case of heavily loaded
leaves, in which deep depressiju of the primary petiole occurred simultaueuusly wiih or immediately
after elevation of the injured pinnule.
Exi'i'.iiiMEN'r v.—August 7th. The day tens one of drenching, tropical showers alternaiing Kith
iniereals of brilliant 'sunshine. The leaves icere in maximal diurnnl ¡mition and in some instances heavily
loaded with adherent drops of r(w>i.—Amputation of the tips of terminal pinnules wns followed merely
by very slow and imperfect action in eight or nine neighbouring pair,-, and, in tho case of one
heavily-loaded leaf, by deep depression of the primary petiole eie any but the injured pinnule
had become elevated. Ilere all tho conditions for excessive turgidity of the tissues were certainly
present, for there had been abundant solar stimulation in coincidence with excessive root-supply
and minimal transpiratory loss, and yet "irritability" in place of being ma-simal, as Haberlaadt says
it ought to be under such circumstance?, was minimal.
ExPERiMBJiT YI.—Saiitember 13th. Almost nniiitciriipted rainfall had taken place during the three
previous days and drenching showers had fallen earlier in the mcrning. The siy ivas bright, itti the sun was vi iled
iy cloud. Ecerything teas drenched tci'h moisture. The leaves tar e in maxiimil diurnal position and in
many cases loaded loith adherent drops of rain.—Amputation of the tips of terminal pinnules was followed
by a pause, during which no movements occurred, but drops of exudation appeared at the divided
extremities of the mid-rib and larger veins of the injured pinnule. Slow elevation of the injured
pinnule then took place. This was sutoeeded by a pause, after which the uninjured terminal pinnule
acted. Another pause ensued, followed by slow movements of elevation in a certain number of
pinnules in the outer half or third of the injured jinna. In the case of heavily-loaded leaves
depression of the primary petiole often occurred as the first sequence to elevation of the injui'ed pinnule
and its fellow, and in one caso as the very first phenomenon of movement subsequent to exudation on
ihe cut surface of the injm'ed pinnule.
Expeiumk^t YII.—October 7ih. Very heavy rainfall had oeeun-ed in the course of tho prerioue night
and during the varli-r part of ihe day. The leaves tcere in maximal diurnal ijoartio«.-Amputation of the
tips of terminal pinnules wns followed by very slow elevation of the pinnules of the injured pinna, tho
movements being in many cases confined to the terminili third or holf of its course. The primary
petiole in some coscs btcame depressed immediately after elevation of the injured pinnule and its fellow.
2. Ejfecis following the amputation of ihe tips of axes.
Experiment VIII.—June 24th, 8 .\.m. Eeanj slmcers of rain had fallen during the night and both
soil and air were very iitwW,—Amputation of the lips of axes was attended by no results, save the locul
exudation of a large drop of flnid on the divided surface.
Exrr.uiiiENT IX.—July loth, 8 a.m. Air very moist and ground saturated owing to he^iy raiu (n
the 2'^'erious i/fi.i/.—Amptitation of the lips of axes was followed merely by the osudation of a large
drop of fluid ou the cut surface.