CUIÍNINGHAII ON PLUCTÜATI0IÍ3 IK TlJEGESOE>'CE.
fi- Strong elevatio
¡ followed by depression,
7. Ditto,
ditto,
8. Ditto,
dilto.
JO. Ditto.
11. Strong elevatioD, action in the pinnules; notbing rao
12. Depression.
13. Strong elevation, followed by depression.
14. Elevation; a pause; action iu tho pinnules; nothing
15. Ditto; depression.
The movempnts of elevation o£ the primary petiole ocourring in s.ioli cases are as a rule follo<ved
by depression, because it is only inidally that the loss ia tarjescenoe following the insolation il oonfinod
to the superior mass of puUinar parenchyma, and because, whan it has
the inferior ma^s, the persistent escsss ia structural strength of its opponent
distal parts of tlio leaf come into play as they ordinarily do. Under circu
loss in turgescance the movements of the primary petiole are alway.= —
the structnrnl features of the infericir mass of pul
to rapid losses in tai^escence, and because it I
aided hy, distal leverage iu giving
m o , ™ . „ l . „( . ! . „ « „ „ .,,™ia occur . t .11 ¡,, l , „ w „ „ , .„ffio¡e„, i„ , 1 , „ t „ i,
. f l m e n t t i . t d„ U i l e r . o t . d l . i . i t .l,o reiA.r, d., P „ , „ o l , jm d.r Ob.r,.;t. i.t m,r Ilill.orE.n
b.i de,. Bewegune. Ther. is .bsolui.lj . „ ,c ,i,.t n , p „ t „ p | „ i . „
pare„ohyma are 1.« oootraolll, those o( 11» iofeilor parenoliym.. Tli. twn of ti„»e
diSer bom one «nolter both .trmlurally and fmotion.Ilj, but Ih, iunoBonal diflorencs. ate tonnoel.d
cot with contractile, but with asaimilatory property. The superior parenchyma is distinguished by esoess
in Btruoteal sirengtli and He interior on, hy eioess iu as.imil.tory activity, and it "s the prcsenco of
these differences, combined wilh the fact that distal leverage co-operates with the superior and directly
opposes the inferior parenchyma in effecting the displacements whioh they make for, tliat determines the
ordinary character of the movements of the primary petitde. It is the presence c,f these differences
and the aotiou of distal leverage, and not t3ie presence of any specially contractile protoplasts in the
inferior parenchyma, that acoouiits for the fact that sudden movements of depression of the primary
petiole are so common, and sudden movements of elevation quite esceptional.
e\tend«d ao as to alfect
and tlie leverage of the
ist.inc9s implying general
fs of depression, because
lar parenchyma are such as to r.-iider it more liable
constantly to struggle against, ia place of being
to the displacement which it makes for. That sudden
The following experimental data illustrate the effect of variations in conditions of distal
in modifying the character of the effects following amputation of distal porti
growing plants:—
Exi-erimest I.-Jvne W/,, 3 p.m. -Rain/a!li„g heatily; pinnuks ai a role elevated or jmrthj ckvat.d
owing to recurrent agitation by raia-dropa primary petioles .fairly well elmdcd in ahnost a!l rases.—Amputation
of the tips of termiaal pinnules in leaves iu whioh they were ouly partially elevated was, in all
eases save two, immediately succeeded by deep depression of the piimary petiole. Of the two
exceptional leaves one was supported by a neighbonring one, and the ot)ier was free of any adherent
drops of rain. The action in the pinnules was in all cases very slow and confined to the injured
pinna, and in most cases was very imperfectly carried out. At 6 p.m. the leaves were all in full
nocturnal position; but although the evening was absolutely stiU and excessively humid, maximal
depression of the primary petioles in almost all eases succeeded the slightest contact impulses. The
influence of distal leverage in assisting to determine potiolar depression comes out very clearly in
regard to both periods of esperimeut. In the former one atmospheric and telluric conditions were
such as to be manifestly unfavourable to the occurrence of rapid losses in turgesoence, as the behaviour
of the pinnules very clearly shows; and yet petiolar movements of great magnitude occurred with
0 frequency because of the abnormal excess in distal leverage provided by the adherent drops of
In the second period also, facilities for transpiratory loss wore minimal, and root-supply was
•Vorlesuns, XXXVII, 3, 7üi,
Í of leaves attached to
APPENDICES. 127
and yet the primary pulvini were excessively irritable owing to absenae of solar stimulation
and persistent excess in distal leverage from adherent water.
Espehiment Tl.-Ju!y 3-30 p.m. Bright but clouded: soil very moid; no rain during the ihre
prcvicua days; leaves nil in maximal diurnal position, tcith their primary petioles horizon!al, slightly depressed,
or very slightly f/crnCerf,—Amputation of the tip of a single pinna, or even of a single distal pinnule,
was succeeded by movements extending throughout the eutirs leaf and including extreme depression of
the primary petiole, whilst amputation of the entire distal portion of the leaf beneath the poiut
of oiigin of the lower pair of pinna3 gave rise to little, and, in some cases, to no petiolar depression,
and was presently followed by extreme pofiolar elevation, although it was attended by conspicuou^
exudation on the cut surface. Here there was manifestly no direct relation between the sevtrlty of
tliR initial iuiury and the occurrence of petiolar movement, but very clearly a direct relation between
the hater and the amount of distal leverage. Had depression of the primary peliolo been dependeüt
on acti^'e contraction of the proto|,lasts of the primary pulvinus incident on stimulation connected
with the sudden propagation of stiiuiilant fluctuations in pressure along the oouiso of Haber-
" Reizlaitendo system," or originating iu any other fashion, this could not have been the case,
landt's
s iiiasimal fluctuations in pressure and maximal injury would under such circumstances have inevitably
Qal in placa of minimal movement. But, as it is a purely physical process, tho tendency to
led to )
T.otiolar depression originating in connection with the fall in turgesoence in the pulvinar parenchyma
incident on the escape of liquid from the cut surface.«, although gi^eater in cases where the entire
distal pai'ts of the leaf were amputated than where only the tips of pinnto or pinnules were detached,
was more or less discounted by the great coincident decrease in distal leverage; whüst the much smaller
mputation of the tips of individual pinraa or pinnules, not being accompanied
ill distal leverage, sufficed to induce extreme petiolar depression,
fully developed nocturnal position. Tho petioles which had beeu
escape
by any appreciablo diminution
At 6.30 P.M. the leaves -
deprived of pinnee were now not neaily so highly elevated as they were shortly subsequent to the
operation, but were stiU more elevated than those of entire leaves; the phenomena ou the one hand
indicating the effects of the loss in tui^gescence in the pulvinar tissues incident on the' cessaiion of .olar'
stimulation, and on tho other the minor degree of petiolar
leverage is greatly reduced in amount.
• depri attending this when di&tül
A P P E N D I X B.
THE KATE OF TRANSPIlt.mON IN MmOSA l>UmCA AND THE EFFECTS POLLOWIVft
SF w ™ ' " " ' Ais-D i i o o r S L ?
The rapidity of tianspiratory loss is so great that the pinnules of leaves on detached axes set in
water, and with their bases subaqueously divided to provide a fresh absorptive sm-face only very
imperfectly assume fho diurnal position under the influence of light unless the degree of atmospheric
humidity be relatively high. The activity of transpiratory lo.s is also very clearly indicated hy the
results whioh attend very inconsidei-able diminutions in the amouut of root-supply as is demonstrated
hy the results of the following osperimeiits :—
KxraiUMENT I . - A pot-plant, tho leaves of which were in maximal diurnal position, and which
had to some extent rooted into the ground through the opening in the bottom of the pot, was carefully
taken up without injury to the projecting roots and was then conveyed to the' laboratory
On arrival there the pinnules of all the leaves were in maximal nocturnal position, owing partly to the
agitation which the leaves had hnen subjected to duiung transfer. The pot was now placed over
a vessel of water so that tho projecting roots were immersed, and the outline apparatus was set in
a sealed chamber. The pinnules rapidly assumed the .m.xirnal diurnal position The pot was now
removed gently from the water-vessel and chamber and set on a table in the open laboratorv and
the pinnules once more gradually passed into the nocturnal position. When they had fully d 4 e so
tl>e pot was anew placed over the water-vessel withia the chamber, and within the course of iwent^
minutes the pinnules w m once more in maximal diurnJ position. On a second removal from the
Ann. Eov. Bor. Gaud. C a l c u i i a Vol, VI.