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Section IV., 1880.

49

Trans. Roy. Soo. Canada.

VI.— Mechanism of Movrmcnt in CwurbiUi^ Vltis and Rohinia.

jB/yD.r.rKN HALLOW,]}. Sc

(Kead May 27, l.SSti.)

The valuiibli' coiilrilmtion.s of Uiirwin ' to our knowlcduv ol tin' uiovcnu'iits of plants,
iiliout ten years .siiicf, lod to an I'.Kaiiiinatiou ol this most iutcrcstiiiii' question, and event-
ually, to the particular I'orm of it to be (liseussed in the present paper. At that time, the
idea of the individuality ol' the cell prevailed, althou<>h Sa.hs had already demonstrated
the continuity of i>rotoplasni through the sieve jjlates ol' ('ucurbita -' and had fbrmulati'd
an expression in which he indicated a stron<>- heliel' in the continuity of all livin<r cells.
It is only v^'ithin very recent years, however, tliat sufli. ienf reason has bpon jriveu lor a
general change of opinion on this question. The additional liuht wliidi has of late been
thrown upon our knowledge of the cell, in its mutual relations, has presented many new
and important subjects for consideration with reference to the physiology of movement
in plants.

In the motile organs of plants — as represented by those now under consideration —
wo have to deal with or!.«'ans which on the one hand are modilied as a whole, with refer-
ence to tht>ir external form, aiul are thus adai)ted to a i)articular purpose, as in ('ucurbita
and Vitis; or which, on the other hand, show these modilications to be strictly localized,
as in the pulvinus of Kobinia. In each i ase, moreover, the internal structure is usually
modilied in an im[)ortant way, and to a strikiim' dcone. In the tendrils of Cucurbita and
Vitis, this occurs in the exct'ssive thickening of the hypodermal tis.sue, which becomes
almost entirely collenchymatous ; in the localized develoi)ment of active fundamental
tissue lying in the outer hypodermis ; and in th.' excessive formation of some vascular
element — usually bast — which thereby product's a mon' or less continuous zone or vas-
cuhir cylinder, internal to the softer parts of more ;ictive growtli. In the pulvinus of the
liobini.', the niodilication is chieily found in the exci'ssive hypertropliy of the hypodermal
tissues, either at the base of the petiole, or throughout the entire length of the petiolule.
In all of these eases, the true relative positions of the tissues, as found in the unmodilied
organ, e. g. stem or petiole, are fully maintained, but the special change developed in
each of the component tissues causes an unusual relation to be established between them,
so far as their mutual tension is concerned. This at once introduces an impr 'vnt lactor
in the conditions of equilibrium which would otlierwi.se be maintained, with the result
that some disturbance of this condition must sooner or later occur, ami this disturbam-e
then becomes outwardly manifest in the lorm of motion.

Since variations of this charact.'r can occur in living tissues only, they must be

Journal Iwnnoun Soc, Vol. ix, 18(15.

■' Text-booli, p. 8'J.
S(H-. IV. lS8(i. 7.

m

50

I'FA'HALLmV ON MKCTIANISM

fV'ii ■ • '?|

'*'

rcliM-n'd i>viiiiiirilv miuI in iii'in'riil tcriiis to .oiHiitioiis of uTowtli. of wliidi llicy ar.' tli..
roult. They iiiav arise, linwi'vcr, as already pointed out, ' either Iroiii uiie(|iial Lrrowib
and iintrilioii ol i>arts. or iVoiii spe. ial eoiiditions of tiiru'esieiice, one or l)oth foiniiin.d
Or. as Saclis stales, " m those niovenienls whieli ortur diiriiifi' growth, the tension of ih''
tissues is eomerned onlv so far as any > haiiLi'e in it veaets on ii-rowtli and niodilies ii
I'eriodie niovriih'nts. and those due lo irritation, mh the i-ontrary, depend i-ntireiv nw
elianues in tlie the tension of the tissues, wiiiih. in this ease, are fully developed oiil\
when tlie origan lias attained niaiuriiy."

These "general ])riniiples npjily to .ill the sulijects now under consideration, and
aceeptin;:- them as tenahle, ^\ e >hall not in the present i)aper concern (Uirselves niorr
j>artic\ilarlv ms to the special ph\ siolouical chaiie'cs involved, and whatever reierences aii'
made to arowth are to 1)e a>('epled in the licneral meaniiiLi' of that term, unless otherwis.-
specilicd. Two iieni-ral <(>nsiderations are of importance in this connection, vi/,, {\ir
niechani( al value of the tissues, and tllV coniinuily of protoplasm.

Of the various tissue's which enter into the i onipo.sition of motile orifiins, parejidiynia,
colleniliyma. bast and wood, are of chief value. ( )f these, the parenchynni prohaI)lv
staiuls iirst as capable of the most rapid i^irowth i.nd the nH)st extreme variations i>\
tension from turLi'escence or other i-ause. The colleiichyma undoubtedly stamls next
inl)oth ol thesi' respei'ts ; while ihe liast, from its more permanent character, as well a^-
from the results obtained by butli Schwondener and Ilaberlandt. ' in which the liieai
elasticity of this tissue appears, is in all prol)ability the most imi)ortant mechanical
element. l)y reason of the retarding" inlluence it exerts upon the growth of the more
rajiidly extending and external parts.

The iiiferciiie wliich naturally lollows from this is. that the principal comlilions of
tension with reference to eldiuiatinii. are csi.ablished and nniintained primarilv bi'twem
the iiarenchyma and collendiyma on the one hand, and the l)ast and other vasi nlai-
elements on the other ; and secniidari'y, between the ])arenchyma and the collenchynia
It will also follow that, whenever one of these last-name(l tissues is in excess, it iiin>l
exert a preponderatinii' inlhu'in'e in ihiuiiics of tension, without special reference to its
particular capacity for such variations.

One of the most important lactnrs in the physiolosry ol' motion, i)arlicularly thai dii-'
to irritation, is the continuity of i)rotoi)lasm. This fact has now been ob.served in so niaiiv
widely difl'erent cases, and involves so little dilliculty in its determination in almost an\
living tissue, that we i an no lonyvr regard its application as a gem'ral law. with reason-
aide dould '. This law is ol' so recent oriLnn. however, that at i)resent but little is known
as to its precise relation to moiion ; but th.it it is connected with it in those cases wiierc
there is distiiKt trausmission of imjiulse to parts somewhat remote from the centre of

' Harwiii, .M(,\.'niiMit^ <■( I'lants, j.. L'. .Sulis, V.,r!e.siiiiL'iMi iilicr niiiii/cii-l'liv >. p. 77.'>.

■■' Texi-lir„,k, 2nil K,l. p. S7s. ,.(,■. M,,ri,.ii. I.a .^^-nsiliilii,' v\ la Motilii,'. dis Ve- ItnixelJoH, is.S,'., |.. .'.•.'..•I. .

" Pas MciiiaMisih,, I'riiicii.. ini .Xnat.iMii.sclica Hiin licr .Mnnoc'ntyl..ii. Lcipnitr, ISTi.

' Pliy8iiilo^'i.M'lic I'lliin/.oii Analciiii.'.

■' 15ot. (ViitrulM. xiv. SD-lL'l. IV..c. I!oy:il Soc, xxxv. K;:;. /'-;./, xxxi v. li 71'. .lahrh. Wi.s.s. Mot., xii. I7n.
VorloHiuincii uLcr rilan/cn-l'liysi(,lofri.', Sa-'hs., lui;. Nuture, xxx. |Sl'. xxxi. ;i;{7, •JlKi, li'.Ki. liuart. .Iciir. Mi.'
Sri., Oct. 18SL'. fl,il. Tran.s. I!ny:,] .•<..,■.. is.s:;, sl7. I'lora, 1st;:!, lis. Haiisteiu, Dio MilcliHill-t(.'ofii.sse, 1^(11. Wil-
hflni, ZiirK(qiiitiiis8 .lea Sidliiolireiigoliisse Din.ivinr. l'llaii»^ii, lS8(i.

UF MOV'KMI'INT IN PIvAiNTS

81

irritation, ("in huvdly be (l()ul)t('(l in the hnht ol' ol.scrvcd larts ' It rnaaiiis to dclfiiniiu.
ill what way tlicsf traiisiiiissioiis ncur ihrouiili the proloplasinic medium. At prcsi'iil,
tliorelbrc, wo must conliiic our .(.usidcvatiuiis to continuity oi' protoplasm, in its structural
rolation.s to the tissues oi'the moiile oruaiis.

In both the ii-rape and the s(|uasli, tiie continuity ai>pears most promiiu-iitly in tho
collonchyma tissui' of the rather thick iiypodermis. It may also he ohserved without
dilliculty in the active i)arenchyma ol all parts external to tlie xylein pjrtions ol' the vasi'U-
hir bundles. The same treatment, howi-ver, does not iuiswer e(|ually well lor its detection
in each case, owiiiu' to the diU'ereiit character oi'the tissues involved. In the pulviiius ot
Itobinia, CJardiner- has already i)oinled out iln' clearly defined continuity which may be
observed both in the jiarenchyina and in the bast. In the latter tissu(! we have found it
to be most strikingly prominent, its exhil)itioii being much less dillicull than in the softer
tissues, probably owing to the presenre of numerous channels in tlu' cell walls, which
serve to localize and more sharply deline the connecting lilaments.

The method employed for the exhibition of continuity must dei)eud upon the cliarac-
ter of the particular tissue involved. Any one of these methods, all of wliich have l)een
employed by Gardiner and others, may be used accordiiui' to circumstances. The lirst we
may distinguish as the salt method. Imh- the purpose there should be prejKired a 10 p. <;.
solution of common salt. This has been recommended by (.nirdincr ' as giving tlie best
resiilts in most cases, an opinion fully coniirmed by our own experience, rerfectly fresh
and thin sections are immersed in a suitable ([uantity of the solution and allowed to lie
until wanted for the linal staining. The action of the salt is to contract ihe pr()toplasm
gradually into a compact, rounded mass, towards the centre of the cell, and tliereby
preserve intact the original conne(liiig filaments, which then become drawn out into long,
slender threads. There is, however, no apprecial)le chain:'*' in the cell wall. A distinct
development of <(>iitinuity will acnerally be formed within a period of ten minutes, but;,
for good results, at least half an hour should be given ; and since, with continued actiori,
the salt con.-olidates all the contracted parts and thus renders all the lilaments more
distinct, an immersion of the sei tioiis for twenty-four or ihirty-six hours may often prove
desirable. If the .solution be stroniivr than in p. c,, the action is too rapid and many of
Ihe more delicate lilaments snap during development, so that we tlu'U observe only their
contracted ri'iiiaiiis upon the cell wall, with corresponding processes from the main
protoplasmic mass. Treatment of this description answers admirably for all unmodilied
I>arencliynia tissue, such as that in the scjuash fruit the lle.sh of the apple and pear, and in
the i)nlvinus of the liobinia. It does not answer so well, liowever, in the case of thick-
walled cells, whether collenchyma or bast. Then one of the followinu- methods is to be
preferred.

The secoml melliod may be distinguished as the sulphuric acid process '. Very thin
se<'tioiis, I'reshly cut— one or two at a time, according to si/. — ^are placed upon the end of
a glass slide or platinum foil. Surplus moisture is now removed in order to secure uni-
form action of the acid. A drop of concentrated sulphuric acid is then placed on the slide

' .laiirzcANski, Ktiulcs ( <.nipam's siir la tiil)c> CviLivux, ISSI. l!ii.ss,.\v. Silzlioiv. iMrpater Natiiif. (i.'S., 18SL',
L'H, LTiT— IC'T. Tmi;;!, I'linn's .laliib., xii. StraMliiirt.'t'r, I'.aii und Waoli.stliiiiii, S.l
■ I'm.'. H(iyal. See, XXXV. l(i:i-l(i<l. '//.;>/., xxiv. -J::! -'-'71.

Ii.it. ("ealialb., xiv. S!) ll-'l.

II

mm

vm

ill!

S2

PKMIAM.OW 0\ MKOHANISM

nv loil, iiaiiifdiatcly al)(>vi' llif siviic)ii>, and allowfil to How ilowii over (li.'in (luiikly,
V.'vy far.-lul atti'iitioii is now ii.Tdd to rontiol tli.' anion at tli.- prop.T inoiiimt. h, tl„.

course .if till- >r four srronds ilir M'.iions acciiiir.- a lain! l.rowiiisli .olor, wlii.li rai)idiy

dicprus a> ill.' d.iivdratiiit; III lion ol lli.- arid prorccds. Its lirst appcaraurc indiratfs, in
most . asi's. liiat ilif action lias hci-n .oniiiiufd louii' cnoimli. Thi- slide is. therel'ore,
qniekly pluiiuvd in a dish of water wliieli nmst l>e ready i'ortliat purpost", and the sections
thorouiihlv washed Tiiey are then ready for staining:-.

The aeiioii of the arid, depeU'lenl upon its (hdiydratiim' itroperties, is lirst to contract
the piMtophisiii it next . ausc,-. the .ell wall to swll stroiiLfly and |)artly dissolve, thu^
renderin<:' it so traiispar.nt as to permit tli.' threads of protoplasm which traverse it to h.-
K'cn distinctly when stained. The sw.'lliiiii' of the wall also tends to i['u\ in the .-ontra. -
tion of tlu- ])r(itoplasm. w liili' lli.' . hann.'ls h.'.ome lonucr, and further ai<l in deliniiiii
the lilanieiits. If Lif.'al > ar.' 1).' not u>ed in this pro.'.'ss, the section will he (juickly iind
wliollv dissolved, '{"his ]irocess is of sp.'.ial advaiitai:'e as a ([uick nu'tliod, while it y'iv.'s
most aratifvinL;' results, and it has lieen chieliy relied upon by us. It may he employed
in ordinary paren. hyma tissue, and also with Lireat advantaiif in lollenchyma and hast, to
the treatment of whi.li latter two, it is best athipted. This is one of the olih-st of all th.'
methods now in use.

The third ni.'thod. and that whi. h (iardiiier si'enis to reirard with the irreatest favor
is the I hloriodide of zinc proces^. This admits of [\\ o variations ; in the first, the sections
are immersed for a short time in an (irdinary a([ueous preparation of iodine, until tin-
chara-teristi.- rea. lion is (h'Veloped. They are th<'n transferred to the chloriodide, when
they ([ui. kly turn dark hrowii, owin^^ to the int.'Usity of the iodine reaction. Alter ah.mi
t.n to thirtv minutes in this lati. i- reaecnt. tiny are waslied out in distilled water until
the l)rowii .olor di.sapi)eais. Tliisnn thod is said hy Ciardiner to have the special advan-
tage tif causiim- the protoplasm in all its parts, to take a much deei)er stain when linallv
colored with aniline. The second variation simi)ly omits the preliminary treatment with
iodine. rrei)araiii)ns hv this nielhod. show the lilanients very distinctly, and the walls
fif the cells so stroimly swollen :is to render them (|uite transparent. It may therefore
he us.'d instead of the last pro.c.s.s l)y >iil]>]iuiic acid.

Sections treated hy any on.- of thes.' methods, re(|uire suhsequent staininu'. in or(h'r to
dillereiitiate the deli. ate hlam.'iits from th.- >urroundinu' cell wall, 'the method oriiiinally
employed hy TaimT, in the .as.^ oi endosperm .ells, was to stain with iodine. Our present
m.ihods. li.iwc\.>r, permit of nun h mor.' ac.urate r.'snlts. The stain reidmmended hy
(lardiiier' as us.'d hy us, iiives most satisla. torv results. It is prej)ared as lollows : — T.i a
.")<! )). c. solution ot al. (diol, add i)i.rii- a. id to saturation. To this add aniline l)lue (w.'
n.sed 151) with e-ood ri'sull^) until llie resi<lual .olor imparted to a section, is deep blue. T.'
fa.iliiat.' solulinn, oiieor twf) drops of acetic acid nniv lie added tothe stain with advantaii.'.
Se. lions previously treated and well \vashe(l, are immersed in the stain Ibrafcw moments
and then washed out in IVesh al. ohol until the yellow is all dischar«rt>d and ihe color of
the seitioii I haiiiics from fr)-,.,.ii to ilear blue. It will then be found thtit the picric a. id, in
passiiifj out from the s.'ction. has Avithdrawn all the aniline from the ccdl walls, but that
it has lelt it in the protoplasm, for which it has a special allinily. The colorless cell >vulls

' l'riii^;irH,.l;iliil... l^sn, 170.

I'lii!. 'I'raiis., .I.xxiv. hl7.

sAl

OP I^IOVKMKNT IN PLANTS.

68

andtht' <olnnHl liliuii.'iils iiic tlmshvonirlit into sliariKontrast, mid tlit- lalttT may easily
lie rt'roi?iii/t'(l iiiidtT a sullirii'iitly liiiili powiT. S<'i timis so pn'par.'d may !)»■ placrd in
tJ.'> p. f. lilyrcriiii' I'or liitun' •■xamination. I'or prrmaiiml mounts, >ily.ciiiit' j<'lly sliould
l»t' iiscd. Halsani will answer lor cxhihition of I'ontintiity in ihc l»ast tissue, and will
t'veii i)veser\e it I'ov several months ill the .xii'ter tissues, hut in the latter case, the proto-
plusmie liliuneiils i^^nidually hieak up. and ulliuuilely disappear.

1. — d'CriiUlTA .M\\1.M.\ AND I'lU'o.

IIlST()i,()(iv. — The tendrils (if the sipiash externally present the I'orta of loiiij-. slender
lilaments, well rouuded. hut with a .somewhat <i-reater transverse than vertical diameter,
and on the upper side Ihitlened and sliuhtly i;roove(l lor almost their entire leimth. The
surliui' is ;at'nerally smooth, tlioxiuh solt sratlering hairs usually ajipear towards the upper
sidi;. The prevailinii' color is a very pale or whitish ureeii. due to the deeply seated
ehloroiiliyll-hearinii' layer, which is internal to the colleiichyma. This ))ale hue, how't'Vi'r,
is Ibund to he interrupted aloni;' three lines, exti'iidiim' from has(> to tip oi' the tendril, in
which the <'olor is a stronj;ly marked iiieeii. thus lirin<''inu' these hands into stronii'
proniini'Uce by contrast with the surroundinu' and liiihter parts. These three lines or
hands of tissue, always oicuiiy the same positions, which are I'.iund to he. one on ea<li side,
just at the horizon ol'the major axis ol' transvi-rse section, and the third in thi' position of
the channel alouii' the upper side of the arm, at the upju'r extremity (.1' the minor axis.
Aside I'roni their more special value in ciniimnutation, these hands serve as most valu-
alde means of notiiifj- <crtain changes incident to movement, e. ij. those ol' torsion. Tlu'
tip of the tendril is invariably turned slightly backward, or towards the lower sich' ot
the tendril arm, though during certiiin phases of the ciniimnutation. changes due to
torsion ol'teii cause it to point upward.

Internally, the tendril presents several important features. Transverse sections
disclose the form and relati(.n of parts shown in I'lale IV, 1m<;-. I. Vnnn this, the following
iletails may be gathered : —

The epidermis consists of a single row of cells, which are either of tlie same siz(> in
both directions, or somewhat elongated in a direction perpendicular to the general surface.
The epidi'i-mal hairs, so far as they may lie present, are conlined almost wholly to the
upper and lateral surfaces at /*, l)eing absent from the surfate below the horizon of the
major axis //. The hyi>odermal tissue consists of a rather thick layer of eoUenchynui (6//),
which is almost continuous throughout the entire circumference of the tendril, its con-
tinuity being interrupted in the three regions a. a\ and an opposite to it'. These areas of
interruption correspond to the three green bands already referred to. The collenchyma
itself is thus separated into three distinct bands, whi.h traverse the tendril tlnnrnghout
its entire length, one l)eiiig larger and inferior in position at //, and two smaller and
superior as at /> and its corresponding part on the other side. The lirst is usually distin-
t-uished by being somewhat thicker, and also of mu.'h greater lateral extent than the
other two coml)ined. The detailed structureof this tissue is shown in I'ig. 3, from which
it appears that th.' collenchyraatous thickening is somewhat general over the entire
surface of each cell.

iili

I

i

-'It'

K

54

PRNITALLOW OS M KCIIANIS.M

',1 !

At the thiiM' points ii.a'.ii". tin- idiitimiity <>!' fh.' collcnrhyiuii is inlorrupltMl liy
"•roups of piir.'iirliyiiiii lissiii'. wlii' h rxt<'iitl as loiiifiludiiiiil Imiuls lhn>u,u:li<iut thcviitin-
lt'iii;tli of the arm. This tissU'- has i irtaiii important (listiiiuniishiiiu' diarai tcristi.s. Tlir
.•.'lis au' usually lari-f, w^'ll roumlcil. and thin walh'd (1ms;. \.(iii', ami Fi^-. .'>). Thi'y .ontain
an ahundan.f ol protoplasm and chlorophyll, and possess all the foatun-s of ctdls in an
active rondition of liTowth. Indeed, the acl 'ity of this tissue is conspicuouH from the
earliest period of circumnutation until loiiir after the surrouudiui,' parts have become
hard and woody, and all motion has ceased. Within the area of this tissue are to he
found iiiterc.dlnlar spatvs (not shown, however, in the lii-nre) loffether with their corres-
pondiny- stomala. which latl<'r are coiiiined to the epidermis of these l)ands. The very
larirt' amount of chlorophvll Ifre pn'senl. i> the means ol that outward distinction t(»
which we have already rcl'eried. Inwardly, each of these uroups of cells connects directly
with the pith reuion of the tendril, thus causini:- a further break in the continuity of the
interior tissui-s. From the very prominent part which this tis.^ue i-videiitly lakos in the
cin umnutations of the tendril, and the lrc(|nency with whiih pointed refereiu'e must be
made to it. we have deemed a de>criiilive term I'ssential. We have, therefore, ai)plied to
it the name ol '• V'ibroeeii '■ <n- ' Vibrouenic tissue, "as siiiiiifyinji" that the orisjfin of the
ordinary circumnutation is to be found there.

Immediately internal to the collenchyma is a zone of rather huL-e. thin-walled pareii-
chvma tissue, c, usually disposed in three or four rows, of which the innermost cells are
the smallest. This tissue, vkhich is I'ssentially the mesophlu'um of the stem, forms a
continuons zone tlirouLih eah of the vibroiicn bands. The cells are tilled with proto-
plasm, and contain some u'raiuilar _ m;itli'r and a small amount of chlorophyll, which
imparts the subdued liieen < olor to the tendril as a whole. The tissue presents all the
chara( teristics of active i:-rowth, but it in all probability is inferior in this resi)ecl to the
«'ner<;y of the vibroii'eii bands — as will appear later — thoiiirh it undoubtedly contributes
its part as a fat tor in the neiieral <ircumnutation. ])irectly interior to this tissue is the
bast zone of the liber. .\t a very early period in the growth of the tendril, the bast
portions .if the vascular bnmlles establish <onjun<'tive growth, and therel)y form a zone ((/),
the (diitinuity of which is interrupted only at those three regions where the vibrogen
establishes its connection with the pith. In its earlier jx-riod of growth, the bast cells
are all thin walled (l''ig. 2 A). They are then in a con<liti(»n of active growth, and are
capable oi Conforming to the sjfeneral and rapid eloiiiiatioii of the organ as a whole. It is
this condition which es.se;itially i haracierizes these cells dnrinu' the greater portion of the
tendriTs active period, bui most conspicuously so during the earlier portions of it. since
we find that, with the growth of the oruaii, the bast cells gradvuilly increase in thickness
and assume more and more completely their trite character as permain'nt structure. And
this becomes more idiisjiicuous towards the end of the active period, when the motion ol'
the tendril is eradiially retarded, and becomes continually more spasmodic, until linally
it ceases altogether We then lind that from thin-walled cells the bast has changed to
thick-walled, permanent tissue, as shown in Fig. :j li. This, then, delines th»' hard and
woody character of the tendril, which is so conspicuous a fetitiare after coiling.

It it. important to point out in this connection that as soon as this woody character
iu the tendril is fully developed, all motion must ci-ase ; and siuce tlie lignihcation is a
gradital process, and will be completed within a definite period — assuming constant

II

OF MOVKMKXT IN ITiANTS.

BB

(■oiidifioiis (.r nulrilidii.— \vi' mu-i icconni/c tlic probiiliility ul' ji liraduiil inodiliiiitiuii in
unironnity, as also (.1' a i^radiial rcssation i>[ niolioii and tli.' iiapo.ssihilil y ol' the activity
hfiiiir pntloimvd or cvrii shurlnu'd; unless conditions of lu'niiancnt contact and irritation
arc cslaldislicd, wlicn maturity is aci clcratcd. As will api)car later, the motion resolves
itself into an expression oi the resultant of activity in two tissues, one of which is con-
tinually growinj?. while the otlier is as continually Jx'comi .less active, and the cessation
of motion must then he determined when the latter eanis . aplete ascendancy over the
former, and thus permanently destroys the e»|uilil)riuni of growth.

Internal to all the histolo<>'ical elements thus far discussed, lie the xylem portions of
the vascular bundles. These, however, are wi<lfly separated. They are seven in number,
the three laru-est traversing the lower reiiion of the tendril arm. As elements of perma-
nent structure, they miist undoubtedly serve in a dettree to supi)lemeiit the mechanical
value of the bast, but to this they are nl)viously very subordinate. AVithin the va.scular
zoiu' is the somewhat laru'e pith which, especially at the base of the tendril arm, early
develops what De r.ary ' designates as a " lysigenetic intercellular cavity." to the extent
that the organ becomes hollow for a considerable distance from its base. This also charac-
terizes the petiole of both tendril and leaf, in each of which the same structural elements
ai)pear, and in much the same relative positions.

Of the elenu'uts thus considered, we must regard the vibrogen, collenchyma and bast
as of primary importance, ami that they bear a delinite ndation to the circumnutation of
the tendril, and to its behaviour under the inllui-nce of irritation, can hardly be doubted
in the light of the facts to be ])resented in the following pages.

11 11

GlJOWTH IN Length. — In vigorous vines, the largest teiulril arm often exceeds •")() cm.
in length. The extreme h'ngths of the tendril arm. during tiie iMitin' period of <ircum-
nutation, nuiy geiu-rally be taken as ranging from S cm. to •■'..') cm. As this great elonua-
tion must occur within the very limited period of two days, it indicates a most rapid
organizing process, as the following determinations will show. Moreovi-r, it must be
borne in mind that the cessation of growth in length and of circumnutation is siniul-
taiu^ous. The following determinations have been obtained. An arm just uncoil(>d from
the bud nu'asured 12 cm. in length. One day later it had increased to 14.S cm., and on
the following day to 1«.8 cm., thus giving a total increase in length of (!.:i cm., or one-
half the original. August 8th, live tendril arms, but a short time in action, were measured
and marked. The Monday following (10th) all except one were found to have coiled
about themselves or other objects. The coils were drawn out and measured with the
following results : —

AiiL'nst Sill..
" Kith.

Gain.

iL'.n IJ.l ir.7 111. -I 17. r. cm.

:j.1.^ 10. 11' ic.d- ::(...:)■" :!:;.<•*

r_'..-) (1.6 7.3 10. 1 l."...">

* Indicates tliose wliich coiiUl not be fully straightened.

' < 'omptirativo Anatomy of I'honogams and Ferns. Eng. I'M. 200.

4V If I '

.; }i

86

im;nii.\i.i,o\v (>\ >fi;<'ii.\\isM

Coil.s J, •'.. I. •'' ' (luM iinl ]»■ lully xtniiiiliti'iicd I'm- iii.'iisiiri'iiifiit. :illo\viin<i' lor wliii h
had ti) 1).' iii:i«l<'. Tliiis il \\i' ii<l<l lo llir ;il>o\ r nuiiilxTs ns lollows: 1.0, ;!.<), ."i.n niid I.M.in.
rt'sp.'ctiv.'ly. \Vf tlic'ii •j:<'\ .in iIh' Ii'ImI l.iiutlix <>[ ;ill tin- tfiidrils. li',."), 7.''.. |(i.;:. 1.'..1 mid
I('>..i 1 111 Wi' lliii." l;i'I :i> till' cxIiiIih' liiiiur in tdoiinalion, liom ."lO per it'iit. to liM) \u-r
ri'iit. t)|' the ((liiriiuil l.'iiiith. im<l the iiifiiii ratio of iin ffa.>«f wotihl hf as ' : 1.14, .^howiiii;-
that the i.udril at Ica^l doiildc.s ill h'tij^lh alter tin- >iii«uiliny Iroiii tlu- hiul, and durin<r
the period ol'tiniuniiutatioii.

|;-.:i !.

('nli.lNii — Wlieii hrou'jlil ill coiiliH ! wiili an olijei t near the lip, Ihe tendril, at oiiee
alieeti'd hy ilie irritation, .oils alioiit ih.' vnpimrt w ilh a lirni i;'ra,s|). The circet ol' irrita-
tion doi'.- not innnediiil.'ly extend aloiii;' the remainder of the tendril, as is shown hy the
I'aet that, when the tip i> InnULiht in eonlaet, the hasal jinrlion ol'thf tendril eonlinties iiv
movement an<l pas^o hv a> a eurvi'. the sensitive surl'aei. therehy l>eroniini>' eonvcx iiisleail

ofeoneave, as wonld (Ml iir if it felt the inllii.'Hi Iroiitaet. After a time, however, the

t'll'ect of eont.K t extends to all I he eells u|' t he l);isal porlioii. wlii(h then draws itsell into;i
closer and closer spiral. WIumi InoiiLrht in iimtaet with an ohjcet, tin' tendril does not
iiiiiuediatelv lose its power of nutation. ImU often retains it for a very eonsiderahle period,
this heiim- tlependeiit Upon the aue of the tendril, and especially upon the particular
state of lignificatioii in the Imst. It becomes evident, therefore, that when the lip is
arrested, the hands of vihitn^vn, still continuine- to act in the hjisal ixjrlions, tend to how

the tendril in all dii lions as hefore. Their power to do so l)ein<r modilied hy lixation o|

the tip, the natural result wonld he fcr the centre to i)ass }>y the jioint of sui)porl as a curve
havina' the sensitive .side outermost. Continued circnmnulation oi the free central portion
hetween two lixed extremities must result in torsion, which will lie riujht or left hainl as
the case may he, hom hotli ends towards the .entre, and when such torsion hiMomes exces-
sive, its comp.'iisalion is of necessity found in a double spiral '. which always char;icteri/es
the lixed tendril. If coilinii- in the fr eiitral portion were primarily due to the irrita-
tion of contact, wi' slionld expi'it to fiml the coiling;' lirst (h'velojH'd as the direct ri'sult ol
simple contraction aloiiu' one side, and this would not imnicdiatidy u'ive rise to torsion
Tendrils whi<h have not sutl'ered ( onta< I. alwavs coil uiion themselves at the completion
of their period of cjfc umnutations. Such coils, however, a..' always somewhat loose and
(juile irreiiular. and are the direct result of excessive ine(|ualitv of ti-iision between the
hast and vibrouen. therefore of une<|Uiil niaturitv in the lissties.

hi

' I

ClRct'M.NUT.iTlD.N. — The lin iimiiutat ions of the tendrils commence as soon as each
arm uncoil; from the bud condition. The central and laru-est arm uenerally uncoils lirst.
and later, the laterals. The whole period of i inumnutation in a rapidly growins; vine,
under favorable eiiiumstaiices, is usually about two day.s— randy three days. Durinii
this period, the motion is at first by <,n-and and reirular sweeps, but it f,'radually becomes
slower a.s the end is reached ; and in the later periods, the movement is s|)asmodic, often
exhihilinjf rest periods alternatiiiu' with those of j^-reat activity. Ultimately the end is
reached iu the formation of a si.iral, which is more or les.s loose and irregular if free, or

I'lirwiii, Cliiiilpint.' I'lanlH, H;;!, etc.

£iii

oi' M()\i;mi;\t in I'liWrs.

d7

COnipilvl jllld Wrll lonilcd il .l..\ .■|(.|...|l ;irt,.r .nlllllrl III nirl, .as." til,, .slnirllli;,! iiiodi-

llciitioMN arc till' suini'. if lli.' pails hr.onii- lianl, .liv imd wdody.'

Th.' liji-un- d.'s.ril>r<l l.v tlir miiaiiini' li)) i> iii)|>r()xiiiiai.-Iy .•llipx.idal (I'liil.. Ill), ili,.
iniijor axis I.rin-r liaiisv.'isiv This axis iiul iiirir(ni..iilly ivarli,.s a l.'iii>'lli of 24 In -21 nu, ;

tlial of tlic minor axis Iti'ino' Irom l:{ lo -^-l

illl. ill IfllU'tll. Ill /■](llitliiri/sfls lohiifii. tilt

diiiiiud.T oi' the liy'iiiv, aic didiii'^' lo Haiwiii . is .-v. mi lart-'.-r than Ihis, ini-asmiiiu' Irom :1H
to 41 .in. While the tendril ihus d,.s.iil...s a limuv, ih,' Vfrtical plan.' of whirh is
parallel with the axis oj' the phuil, lii.- spa..' ihrouudi wlii.h tin' lip niovcs is yrcally
au<.Mn('iitfd hy a supi)lc'nic'ntary iiiov.'ini'iit in th«' >>io\viim' .-nd ol th,' \ in,' on which the
tiMidril is loiiiid. This s(',',.ndaiy niovcnii'iit <aus,'s th,' Iciidril to d,'s,ril),' a douhlf
motion, which increases ihc possildliiy of its contact with siirroundiii'j,' ,.l.j,'cls/ It is ,>!'
short duration, however, since th,' nio\ cnii'iit ofth, vin,' is,(inlined lo ih,' lew internodes
at the end, and at any one noile ,()Mtinues lor tw,i davs only after the l,'ii,lrils an' in
motion ; so that. Iiy the time the lir.sl .irm,.l" the lailer has u-rasp.'d a support, th,' move-
uuMit of tl»e vine at that particular node iii.i_. Iiav,' tvased eiilirely. So loiiy: as there is no
conlHct the tendril continu,'s to revolve, uiitii a {iiadual iuciva.se oj permment tissue
arrosts its activity.

Circumuutations do imt lielonn' t •;.,' tendril an ' alone. Not only tlo,'s the petiole
of »>uch tendril perform a delinite cii' uinnutat; 'U Imt th,' leaves ,'xhil)it a similar inovi'inenl
ill a maikod (h'u'ree, as demonsirated l)\ (i 1',. ('(udev during' the past suinm,'r, Tlu>
motion of the tendril petiole is best oh .'r\,(l hy Darwin's ni'Mhod ol a line <>'lass lilaiiient
with a snuiU black head at its exlreniii y. ins,': I. d into the end ofth,- pi'tiol,' where the
arms separate. The circumnutation of the 1,'af is I,) li - d,'t,'rn)iii,'d IVoiu its tip, as in
tendril motion. In this manner, we ha\e ohtained, |V,)m a leaf of medium size, a iiuur,'
of twenty dillerent clianiri's of dir,', tion, within the sit.i,',' of three hours. The movement
was ibund to be much slower, and tin' lii^^ur, much small, 'r than in th,' ,'a>e , if the tendrils.
This, liowever, would appear to b,- the case fnui: tlieoivtii'al consideratiniis. when we
compari' the structural features of the two and have due reij;'ard for th,' diU'en iice in si/e.
The ii<r\ni' described Ijy the leaf, so far as formed, was (juite regularly I'llipsoiilal, liiouuh
the curve was retraced b,>fore the ellipse was fully completed, in all of these respects
showini^ striking similarity to the movement of the tendril.

During a series of observations extei'dinii' over a period of nearly on,' week an.:
embracing both day and night, almost ilu' entire cinumnutatioiis of each tendril oKserved
were .secured. Temperature and other conditions were noted at eaili of the observations,
which were taken at intervals of from two minutes to one hour, accord'ug tu the
coiiditiou of activity. The following are the results ; —

rendril No. 1.— Aug. 12th, at O.-'.O a.m., one of the longest arms was selected after it

' My „li.serviili,>ii» .■eiilirni t!''".(M,l' [)arwin will, wjurd lo ,.iIi,m- nifiiilvrs of tlic Ciu'urliitaco;,, tliiit when
a spiral iltivol()|i.s freely, it i.s alwtiys simple; tliat it only n'ver-cs wiicu tin' tip is attaiiieil to u.snppoi

■■' f'liailiint: I'lant.s, li's, ,.t,'.

•' The tiul thai there is tliis .hml.le ni,.ti,)ii as a re.<ult ,'f t,.M,lril vine a.ti.,n, slmus that the true fi.i-'ure is to
1)6 obtaiiMxl only when the tendrils revolve about the inner surf.iee of a '-'la.ss j:l,.lie ;nul the ehan^'es of dirctiun
are reeordwl fmm the ontsidi^ This, la.wever, was not praeticahl,- in our ease, nor was it esseniial to tlio a,'enra,'y
of the concliLsions to l)e ol>taiiu),l. For ,)in- p\irpo.se, the iilane reconling surface was amply butlieiont.

fck<r. IV., ISSti. S.

■rW*

S8

Pi;X II ALLOW ON MKCMIAXISM

Imd hci'ii soini'tiiiif uncoilt'd, ;ni(l its movoiniMils \v»'n' noted until tlu'rc was no Curthfr
motion. The cntiiv period of ohsorvation was ti'ii hours and thirty niinuti's. During-
that timo. the tendril lip tra versed i distance of 34:3. 1"» em., ttivinu- au avoraj^e rate of
;».r)4 em. i»er minute.

The g-reatest rate of movement, at anv on(> time, was 2.0(! em. per minute, and oeeurred
two and one-half hours after the wave of maximum teinperalure had i)as.sed. The waves
of most rapid movement extended from 2.80 to 4.80 p.m.. elosely followintj the greatest
heat wave. The waves of slowest movement eovered tlio time from 10 a.m. to 2.-30 p.m.,
eoiiicideut with a risiiiL;' teuijieralure. The al>solule minimum of motion oeeurred Just
before the maximum of temperature, at the rate of 0.21 em. jier minute. At four o"<'loek
in the morninu-. a heavy rain eeascd. The air was sureharged with moisture, and the
sky was I'lilirely overcast with heavy clouds. It was while this condition lasted, that
the waves of slowest motion occurred, the al)solute minimum being found durinii' the
period from 12.!.") to 1 p m. At the latter hour, the clouds broke aiul the sun came out
brightly aiul so continued until il p.m., when the sky again became overcast and rain .set
in at 7 o'clock. AVhile the sun was out, the tendril was most active — tlie absolute
maximum of motion takinu' place within the liv(« minutes I'rcnn •"),2.") to :?.;5o p.m., the
distance travelled in that time being 1(!.:50 cm.

The tirsi direction of movi-ment was to the ri^'ht. This, however, was obviously
aecidt'iital. since the direction llrst recorded must depend ui)on the time of llrst (d)servation
with relation to the entire movement — dextrorse altermitinii' with sinistrorse movement
duriim- the whole period of activity. The total motion to the right was lltO.s cm.: that
to the left, 1.32.;i.') cm. ; and the ratio therefore, as I : O.T'.t.

m

Tendril Xo. 2. — Sclecte<l for observation. Auu'ust L'lth, at S o'clock. It was a shorter
arm than No. 1, and somewhat nearer tlu' end of a<tivity. The time of ol)served
movement was six hours and lifteeii minutes, and the whole dist.ance tra\elled l:](;.00cm,
thus irivingan average rate of 0..'3(i. cm. i)er minute.

The absolute maximum of motion was l.Td cm. per minute and occurred from 10.1">
to 10.20 ;i.m.. forty-live minutes bdorc the maximum temperature for the day was reached
The waves of mo.st rapid inoiion co\ered the period from s lo lo..")0 a.m.. coincid(>nt with
increasing tempeiature. 'flie waves of least motion occurred between lO.')!) a.m.. and
2 p.m., durinn- a sliuht depression ol temi)erature. The absolute minimum was reached
between lo..-,(i;i iii.iiiid 12.2."i.and amounted to O.ITM. m. per minute. It directly succeeded
the maximum of temperature. Durimr the entire time of observation, the weather wa>
very pleasant, though somewhat . loiuly. At 12 o'clock, the le;ives began to droop from
the ell'ects of excessive heat and transpiration. This .ontiimed until after the close of
observations. It was during this time of depressed activity, that the minimum motion
occurred. Duriim- the entire morninu'. all the leaves and llowers showed uTeat viii-or, and
it was while in this condition that most active movement took i)l;ice. The lir.st motion
observed, Was to the left, and was not replaced by dextrorse lor some time. The entire
sinkstrorse action was !i4.2 cm.; the dextrorse, 41. S cm. ; and the ratio ol' the latter to the
former was therefore, as 1 : 2.2;").

Tendril No. I}. — The time of observation was ten hours and thirty minutes, commem-

'I^ia

OK .MOVH.MHNT IN PLANTS.

39

,'M

ing at 10 o'clock, ii.m., ou Auoust l;{ih. Th.- whole leiigtli oi' movement was ;5:i!i..3n ,m,
and the rate per minute, i).:r2 cm. The tim..s ol' greatest movement were Ironi I to S.iri
p.m., and again from o.l.". lo S p.m., tlie I'ormer occurring at llie time of the maximum t-ui-
porature, the latterona diminishing temperature. The absolute maximum ot moiion was
:!.;jr. cm. per minute, and o.vurred IVoni l.r.Uto l.:.:2 p.m. succeeding the wave of maximum
temperatun^ by two lumrs and lilty minutes, at a lime when there was a slight tempo-
rary depression oi' heat. The distance travelled in that short interval was 7.10 cm. Tlie
time oi' k'ast movement was I'rom IJ.i:. to 1 p.m.. durinif the time of ereatest heat, and
aa'ain from .'MA to .").15 \}.m.. following a diminution of temperature. The absolute
minimum of motion was u.Ol.'i em. per minute, and oc. urred from \±\') to 1 p.m. on a
decreasing temperature, following the maximum wave by one hour aiul lil'teeii minutes.
During that lime, the weather was pK'asani but somewhat cloudy. From 1! a.m. until
•"> p.m., all the leaves aiul lh)wers were droojiing. indicatinii' a weak vital action through
excessive transpiration. Tlie lirst nu)vemeiii recorded was to the right, soon siu'ceeded
by a reverse to the left. The entire amount of the former was liiil.o cm. ; of the latter,
(iT.Hcm. ; aud the ratio as 1 : 0.2.').

Tendril No. 4. — This tendril was taken Auu'u.st 14th at 8 o'eloek a.m., but so late in
its uTowlh that only twelve movements were obtained, covering seven hours and lifty
minutes in all. The whole length of movement was M:2^\ cm., aiul the averaire rate per
minute, 0.14 cm. At no time was there any ixhibilion of very ixreat arlivity. the tendril
appearing to move as if in tlu' last stages of growth, whiili it icallv was. The most rapid
movement appeared from '.'.4 I to ii.'iO a.m. the extremity passiim' throicjli 7.7 cm. ni nine
minutes— an average rate of U.S.", r\n. This coincided with the higlicst temperature, aiul
was just i)rior to a fall of two deuTces. The time oi' least ariivity was from !».'>•) a.m. to
3..")0 i).m. The absolute minimum of motion was from "2. 10 to o.."ii) p.m., amounting to
iMi;]l cm. per minute. It occurnMl on a deercasinu' temperatiue. live hours and lifty
minutes after the maxinuim tcmiicratiire had i>a>si'd. l»iniiu;' that time the sun was
shininu' brightly, though its eli'ects were sonnnvhat modilied by numerous clouds. From
I'J ocloek to the close of observations. <luriiiu- the time df least activity, tlie leaves and
Mowers were all depressed from the eli'ects of tlie heal.

The movements lirst recorded were to the h'l't, but alter two courses ihaiiued to the
right. The total dextnu'se movement was Is. 4 cm.; the siiiistrorse \'.s^\ em., and the
ratio 1 : 2.0.

Tniilril No. ;"> a.— Tliis was taken Aiu;-. 14th, at 4 o'clock p.m., as soon as it had emerged
from the bud condition ; thus verv nearly the lirst nutations wi're secured. Observations
Were interrupted after a few hours, and not resumed until the next moniiiiu'. The entire
lengrh of niovemeut was I(i7.tl(l cm., occupying lour hours and thirl\ miiiules. thus
"jiving an average rate per minute of ii,:l'." cm. The greatest movement was at the rate ol
1.44 cm. per n'inuti", and occurred from 4 io l.n.". p.m.. at the very commi'iicemeiit of actum
and observation. The times of i>reatest movement occurred from 4 to 4. ■'].") pia., and afun
from ,').:{() to 7 p.m., coincident with decrcasii;u' temperature.

Least activity was noticed at 7.")'> to H.pi, when the ti|) moved at the rate of 0.13 cm.
per minute. This occurred at the lim.' of lowst ob.served temperature, the meivury

i"l

Jl

60

PKN HALLOW ON MKOIIANISM

standing at 210. Tin' times of least movonu'ut were ibund to extend t'rom 4.35 to 5.30,
and again IVoni 7 to S.30 p.m., wlieii the observations cea-sod.

At tlie eommeneiMnent of oljservations, the sun was shining briglitly, and the effeets
were svillieiently .>«tronu' to cause a (h'pression of all the leaves and liowers. Shortly after
observations eeased, the .sky beeame cloudy, and at 9 ocloek there was a heavy shower
which revivi'd llu' whole plant, and once mmv brought all the parts into active condition.

The first movement recorded, was to the left, action in that direction predominating
during the entire period of ob.servation. The total movement to the right was 18.80 cm. ;
to the left 88.8 cm. ; and the ratio, therefore, as 1 : 4.7-J.

Tc«^/n'/ iV(». .') b, c. — This n'presciits the same as the ]>receding tendril, observations
upon whit h were interrupted Aug. 13th at 8 p.m., and n-sumed the next morning (LMh)
at 8 o'clock, being continued through ihi- 14lh and 15th. During the night, the arm was
quite active, and in the morning showed no tendency whatever to di.seontinue its nuta-
tions. From tile time indicated, observation.^ were continued for twenty-four consecutive
hours. The entire distance travelled durinti' that time was 5n.7 cm., thus giving an
average rate of 0.37 cm. each minute. 5 l)-c. indicates a change of paper, which occurred at
(1.20 p.m.. at a time when the tip hud dropped to the ground, where it remained without
change of position until 8.-"!5 p.m.. when its nutations were resumed.

The time of most rapid movement, was during the two minutes from 4.55 to 4.57
p.m., on a decreasing temperature, and live hours after the maximum wave had pas.sed.
The rate of movement was 4.55 cm. ])er minute, the times of most rapid movement
occurring from S to 10, 2n a.m. : l.'ln to 2 p.m. ; 4 to 5..",(> p.m.. and 10.53 to 11.05 p,m, ; the
maximum of these ])i'iiig from 4 to ."i,.>o ]).ni. The ab.'^olute minimum of motion occurred
from 4 to 5.04 a, in,, when the tip traveled at the rate of 0,043 cm, per minute, this being
at a time of low temperature. The times ol least activity were from 10,20 a.m. to 1.30
J). 111. ; 2 to 4 p.m. ; 5.30 to 10.53 p.m. ; and from 11.05 during the remainder of the night,
and until the end of the experiment ;it 7 o'clock in the morning. In these ol)serva-
tions. there appears a very sharp division at 5.30 p.m., between the waves of more rapid
tliurnal, and those ol slowci' nocturnal movement.

The experiment commenced witli very plea.>-ant weather and all parts of the i)laiit in
vigorous conditiiiii — the leaves beini:' erect and the Mowers fipeii. From 12 m. to 4 p.m.,
the leaves were drooping and the activity of the plant small. This, with the exception
of one-half hmir from I.-'lo lo 2 p.iu.. was a time of slow movement. At 4 o'clock p.m..
the leaves began to resume their normal, fresh appearance and so continued until the
close of observations. Towards morninu-. a very lieavy log gathered and reached its
maximum at lour o'clock, the time of minimum motion.

Sinistrorse movement was lirst noticed. The entire dextrorse motion was 282.1 cm.;
the sinistrorse 229.t!, and the ratio 1;U. HI, thus showing a gri-ater tendency to ecpiality
than previously oltserved.

The ligure described duriiiii- the movement of this tendril — rediK'cd to one-half the
actual size — is shown in I'late 111, the position of the ol)server corresj)onding to the base of
the tendril. Tlie following tal)le relalinu- to these movements will convey a fairly accu-
rate idea of the general features of circumuutatiou witii referenct! to time and distance : —

OF MOVEMIONT IN PLANTS.

01

1

2

3

4

■5

(i

7

8

9

10

11

12

13

14

15

1(1

17

IH
l!l
'.'()
21
22
23
24
25
2(1
27
28

DistaiK'o
in cm.

.0

11.(1

8.7

20.6

14. S
2'.t.(i
10.1

7.0

15. 2
7.0
7.2
7.S
S.O
7.3

IS.S

s.s
7.4
5.7
4.1
(1.4
17. .^
3.5

1(1.2
(i.S
().()

Time.

.s.Od A. M.

8.25 "

8.40 "

0.15 "

0.40 "

10.(10 "

l(t.l5 "

10.20 ■•

11.00 '•

11.25 "

12.011 M.

1.00 1'. M.

1.15 "

1.30 "

1.3,-) "
1.45 "
1..55 "
•J. (Id "
2.20 "
2.45 "
3.0(1 "
3.2(1 "
4.00 "
4.1(1 "
4.30 "
4.45 "
4.50 "
4.. 55 "

Temp,
(leg. C.

24

4

35

5

35

.5

3(1.0

3ii.(i
33.3

32.2

.\iiinl)or.

30
31

3.4

35
3(1
37

;i8
:!0

4(1
41

5.4(1
(i.20
.S.35
8.47
0.00
9.. 50

42

l,s.,s

ll).5.-i

"

43 i

7.">

11.05

i(

21.1

44

0.0

12.00

((

20.0

45

I.-..1

12. 3,5

.\. M.

4(1 !

7.2

1.00

"

20.0

47

25.0

2.00

"

10.0

48 i

.S.2

2.20

40

0.7

4.00

"

18.0

.">()

2.S

5.04

"

10.0

•■-1

0.4

5.30

((

52

(1.0

5.45

11

10.0

53

(1.0

7.00

(1

20.0

Totals. ■;

511.5

23 li.

577.8

Means . .

9.8

2(1.5

m.

20.3

Tendrit No. 0.— SeltMti'd Aug. 1. at 1.4") p.m., wlu'ii l)ut n short tiino from tho bud.
(_)b.s('rvations wi-ro contiuuod .oii.^ccutiv.'ly lor cii-htecu hours luid liftoon minutes. Th(3
distaiu-e througli which tho tip movod during that time, was :!27.8 cm., an average rate

per minute of 0.2!» cin,

Most rapid movement o.-eurred from »;.5<» to ll.'iS pm.. at the rate of 0.5 cm. per minute.
This was on a decreasing temperature, and six liours and forty minutes after the wave of

^

'i'ifi

62

PKNllATiLOW ON MKOHANISM

maximum tomporatuiv had passod. The time of the s-rfatest movement was from .'5. 50 to
7.10 p.m. on a de(rea,><ina- temperature, and witliin tlirco degrees of the lowest phase of the
thermal wave. The times of least movement were from 1.45 to 3 50 p.m., and from 7 p.m.
to the ilo.se of observations. As in the precedinu' case, there was. in this, a marked distinc-
tion between the waves of more nipid diurnal, and those of slower nocturnal movement —
the time of division beinsi' 7 i).m.

The tendril commenced its notations with a dextrorse movement, and in its entire
activity manifested a areater equality between right and left motion, than in even the last
liise. The dextrorse movement was Kit!. 10 em. ; the siuistrorse 1<!1.7 cm., and the ratio,
therefore, 1 : 0.!'7. At the commencement of observations, the sun was bright, and the
temperature hiu'h. The vitality of the plant was mm h depressed, and the action slow-
all the parts droopinii" from excessive transpiration. Tliis continued until 4 p.m., during
whi>h time there were slow waves. .Vi 4 o'clock, the plant revived, tiie leaves became
erect, and the normal . ondition and activity were once more restored. From that time
until sunset, the waves of greatest movement occurred. The sky was clear until after
midnight, but slow waves loutinued throughout the remaiiuler of the night, with a
slight acceleration just after sunri.-^e.

Tendril Xo. 7 a. — Observations commenced Aus:'. Itith, at 9 o'<-lock, a.m, and were con-
tinued for ten consecutive hours. The total distance covered, during that time, was ■227.1
cm., or at the rate ol »i.:is em. per minute. Tlie time of most rapid movement was from
5 to 5.20 p.m.. when the tip moved at the rate of 0.02 cm., per minute. This occurred
just at the outset of a rMjiid de( line in tenii)erature, and six liours alter the maximum of
temperature had passed. The time of iiicatesi moxenient was from -"..bl p.m. to llie close
of the observations at seven oclock, lo-incident with a rapid decline in temperature.

The time of least movement was from 1.42 to 2.25 p.m.; the tip moving at the rate
of O.o.') cm. pi'r minute. This was durini;' high temperature, but one hour and forty-two
minutes after the maximum had pas.'<ed. The waves of least motion were found to extend
from 0 a.m. until :1.15 p.m., with a marked retardation towards the latter hour. The.se
waves were coincident with the greatest heat wave, the greatest retardation of motion
occurring just after the maximum temperature had i)assed.

Th>' exiierimeiit commenced with the sky clear and the plant in active condition. As
the heat increased, however, its effect upon the plant was noticed, and at 12 o'clock, willi
the mercury at ;J4.4' ('., the loaves drooped, aiul the whole j)lant was in a very flac( id
condition. Duriim- this time, the waves of slowest motion o<'curred. This condition
continued until, with I'onsid.'rable fall in temperature during the afternoon, the normal
tension and activity of the plant wi-re restored, when the waves of greatest activity
were noted. The entire dextrorse movemi'ut was 02.'.M) cm.; the siuistrorse 134.20cm.,
and the ratio as 1 : 1.44.

rr

7V«r/n7 V(A 7 I), c. — This Wiis the .same as the prec edini:', observations iipon which
were discontinued during the night, bui resumed on the morniim' of the 17th at 8 o'clock,
and carried over a period of seven hours aiul lifty minutes. The entire movement during
this time was '.i4.40 cm,, giviny- an averai^e rate per minute of 0.2<l5 cm. Most rapid
movement was at the rate of 0.555 ( ni. per minute, and occurnsd from 8 to 8.15 a.m., at

01-' MOVKMI'INT IN PLAXTt!.

63

the very .ommiMicPin.'nt of observation, iiiid on ii viRiiii.- trinpoviUuro, .six hours beforo the
maxiinum was reacht-d. Tin- wav.'s of most rapid motion were found from 8 to 11.80 a.m.
I.oast motion took phiic at !.:!(» to 2 p.m., at the rate of (».08 cm. per minute. This was
just ut the time of maximum temperature. The waves ol' b'ast motion were found from
ll.:50 a.m. to the close of observations at ;!.4(» p.m., .oincident with a rising and maxiinum
temperature.

Observations commenced with a moderate temperature, cb'ar sky aiul an a<tive
condition of the phnit, continuinpf tlius durinu' the time of greatest movi'ment, until, at 11
oclock, the leaves l)ecame depressed iVom the elfeits of the heat, and from 11.80 on, the
waves of slow motion wer(> found. At 12 m., the sky was overcast and the air loaded
with moisture. At 1 p.m., the leaves were restored to their normal condition and erect
))()sition. At th.' same hour, rain commenced and continued during the remainder of the
experiment. The total movemeni to the riaht was 2'). 10 cm.: to the left. (;i»,8i) cm., and
the ratio as 1 : 2.7t>.

Tenilril No. H a. — Selected Aug. Itlth, at 1> a.m. — The time of observation covered a
period of nine hours and fifty minutes, or until ti,.")(t p.m. The entire movement during
that time was 314.50 cm., giving an average rate per minute of 0.")1(3 cm The time of
greatest movement was from 8 to 3.1.') p.m., and the rate i»er minute 1.20 cm. This was
on a decreasing temperature, four hours and lifteen minutes alter the maximum. The
waves of greatest movement were found iVom 2 p.m. until the end of observations, and
during a diminishing temperature.

The time of least movement was from 11. 2o to 11.4(1 a.m., and the rate per minute
O.lOrt cm. This was at the time of maximum temperature. The waves of slowest
motion extended from 9 a.m. luitil 2 p.m., with sliglit acceleration of movement towards
the latter hour. Observations commenced with a bright sun and the plant in active
condition. At 12 o'clock, the leaves drooped, with the thermometer at 34.4' C, and this
condition <'ontinued until early in the afternoon, when Ihey revived v.ith decrease of
heat It was during the passive condition of the plant that the slowest motions were
observed, the more rapid waves occurring with renewed vigour and greater tension of
parts. The entire dextror.-"*' motion was 14:'. 10 cm.; the siuistvorse lt;i.40 cm., and the
ratio, therefore, as I : 1.12.

Tcmlril iVo. 8 b. — Observations were resumed at n o'clock a.m., August 17th, aiul
were c(mtinued for seven hours and forty-live minutes. The distance which the tip
travelled during that lime was 22."). 0 <in.. or at the average rate of 0.4S8 cm. per minute.
The greatest movement was at the rate of 2.00 ,m. per minute, occurring from 8.40 to
3.45 p.m., at the very close of observations and one hour and forty-live minutes after
tht! maximum of temperature. The waves of most rapid movement were from 3.1')
to 3 45 p.m. Least movement occurred at 10.15 to 10.30 a.m., at the rate of 0.10 cm. per
minute. The waves of least motion extended from S a.m. until .•'>.15 p.m., coir.iident with
a rising and maximum temperature. Observations corameneed with a bright sun and
the plant active. At 11 o'clock a.m.. just thirty minutes after the minimum of motion
occurred, the leaves were all droopinsi' as a result of excessive transpiration. At 1 o'ckxk
p.m., it wjiK raining, and the normal activity of the plant was restored. This continued

;:fl|'

^ m

64

PENHALI-()W ON MKniANISM

m

f

until tht' dose of ohservntioiis. The fiitirt' (loxtrors« aotioii was 10:!.')0 cm.; the
sinistrorse 121.50 tin., and the ratio, thereloie, as 1 : 117.

Tendril No. 8e. — Observations upon the tendril were resumed on (he 17th of Aucfust,
at ;■) o'clock p.m., and exti-nded <>\,"r liftecn hours. Apparently, on account of its atje,
and the time of observation, the entire movements wer(> slow, amounting- in the whole
period to only l'>!».o cm., thus irivinif an averau'c rate per minute of 0.17(1 cm.

The ijreatest movement was I'mm 7.1i' to 7.-'S pm., at the rate of (l.t;r> .ni. jier
minute. The waves of most rai)id movement were from o to l.-W p.m., with a slijrht
acceleration in the morninu-. Leiist movi'ment was found from 2.:!0 to 8 p.m., iit
the rate of 0.0-2:5 cm, per minute, oci urriiiir at the time of minimum temperature. Tlie
cxtri'me variation of temperature durint;- the time of observation was only 2 C A liiilit
rain fell during' the liicatcr part of the time, aiul heavy clouds obscured the sky the
remainder. The dextrorse movement was 117.'' 'u. ; the sinistrorse 41.40 cm., and the
ratio as 1 : 0 35.

Tvndril Xo. 9. — The last tendril ex]>erimented upon wa^ taken August 17th, a! ti
o'clock p.m. li WHS in the last stimes of movement, and exhibited the least horizontal
ranti'e. The whole length ol' movement was lin.MO cm. : the time sixteen hours and
forty minutes, and the conse(iuent average rate i)er minute was O.litl cm.

The greatest movemeni was irom 7 tt> 7.0() a.m., at the rate of 2.17 cm. per minute.
This occurred from It. 30 to 10.00 p.m.. at the rate of 0.02 cm. per minute. The waves ol
slowest motion were found from 0 p.m. until o a.m. The temperature varied only three
degrees during the entire time of ol)servation. I'rom the commencement until 10 o'clock
p.m., liirht raiji fell and the sky was entirely overcast until the close of ob.servations. .\i
•'• a.m., there was a cool east wind, with a very large amount of moisture in the air, ami
the plant was in a very active condition. .\t the close of obsiTvations, heavy rain com-
menced to fall. The total dextrorse motion was 100. 40 cm. ; the sinistrorse 30. IH) cm. ;
and the ratio as 1 : O.lSl.

CiKNKH..\I, St'MM.VK'Y.

Aveu.m;!': K.\tk Ol- Movement.— From a total of 4:!tl distinct observaticms upon the
motion of the tendril under all conditions (tf temjierature and humidity, it is reasonablv
safe to assume that the averaue rate of movement <leduced from them, will represent with
api)roximate a<nu-acy. the true normal rate of movement tincb-r all the oi-dimiry c<mditioiis
of growth. This rate we lind to be o,:Jltj cm. i)er minute.

M.wiMUM R.\TK OK Movement.— Hy reference to the .iccompanying tabh", it will be
seen that the maximum rates vary very widely, and also, in the same tendril, that thi-y
usually occur in waves, as in ."• «. .'•/>, r. etc.

IMii

ol' MoVKMKN'l' l\ I'LANTS.

Kii.MKiN- I.I ri;MiM;i;\Ti rao Id 1!ati; oi MoviiMr.sT.
(.I'oi;. ('. Histaiiccs ill ciu.)

68

1,

•")'.,-■. (I,;,/,.

7h. H,i.

s/..

■S''. v. Means.

"■•''' l'."C'ii II. 1 III ii.;;i| ii,:',7(i ii.Ji.Ki ii.;is(

>o o.L'iM o..Mi; ii..is;i (i.i7(i ii.nii (i.nm

A\('rii^'(' rate, jn-r

I IlllllUlC (I.

I .Max. rail'. ;il'

inov.Miu.iil. .. L'.oil l.7(i ;i„v,(, n.s.-,(, |.4| .|..v,i, ,i..-,,ki ii.;i-J(i ii..Vm 1.-Ji,(i l-.(;,i(i i).iir,(i •> 1711 ■> -u:
1 iMii|p. Iiir max. " —

,'■"''■ .■■•• -■"'■■''" -'■'■'" -'" .'^l"i:!"i"<lilil'7.L'ii I'.li'.iOliL'l. lrnL".i.(ill(lL'il.lilio:;|.7(iii-J".-'(iO''ii..-,i)()-'l Iii(i->i; -,iif)

Mmiito ralo cil ---_..

iiM.wiMciit. .. ii.i.'l (i.l.s (I. Ill;; o.i,:;| |,,i;> ,|,||.|;; ,|,,|_|; y,|-., II 11^,, ,,,,.,. I, ,111, II, |.,.. II ,.j.,,^ 1,1

Icmii. Iiir mill. " - • ^

I '■'1*0 I'.l.lii ::i.7o L';i..-.(iii:;L'.L'onj|.7(i Ki.rnnL'i . iiiii:;i .Ui(1l'l'..soii ;M.ii(i2t.iiniii'.i..-.niijn. (111(1^7. ;;oii

It' wc oxiimiiu' tlicso results in th.'ir roliilion to the ext.'rii;i] coiulilioiis ol" g-ntwth,
Iheii we liiid thiit. of the thiiteeii ujiseiviilioiis uiveii. only Itmr .show waves of rai)icl
iiioveiueiit duriim' the iii(>riiiii<>-. llie.se o, . urriiiu' hrtweeii the hours of 7 and 10. iO, aiul in
no case — unless we exeejit No. M— represent inn' the nhsd/u/r mii.rimiim (if motion for flu: irliok
lijr of Ihr Iviidril. The reinaininu' nine show the waves to occur in the afternoon, from l.oU
to 7.12 o'clock. U, moreover, we select those linuu-es which represent the true maximum
of uu)tion for the entire period of activity in eacli tendril, we shall lind that only one such
occurred in the morning, all the otheis takinu' i)laco in the allernoou, between the hours
of l..')(l and »;.")((.

Jvjualizing the hours of day iiiul niu-ht. makini;- the time of division 7 a.m. and 7
p.m., we lind the total leniith of diurnal movement to he l:3r)ii.!t() cm.; and of nocturnal
movement to be ."i:!ti.'.t(i cm. ; thus makinii' the latter in the ratio of 1 : •!.■)■) to tiic former,
a dill'erence which clearly indiiatcs that lemi)craluii' exerts an inllueuct' which far
outweighs any rctardini'- elfed due to the "realcr inllueu<'e of sunlight.

This naturally raises a question n'lative to the temperature un<ler which these
maxima were obtained. Th(> values for tendrils i. :!. .'i A, r, ijaj). Sb. and '.•. the six highest
rates ol)served. were obtained when the temi)erature ranged from 21.1' C to ;10 ii . Of
these, the highest late.s, viz., li.'id. I..").'), and -l -"I'l. were olitaincd when tiie thermometer
ranii'eil from 24.1 C to :!'•.!• ; the other three yivin;.'- values of 2.17. 2.t!0 and 2.0(). were
obtained between 21.1 V. and 2'^.•''. . We thus lind that the more active of these waves
were Ibrnied under the inlluence of a lemjierature .'LS ('. higher than that under which
the less active were produci'd. Aiiain. taking the hiu'hest rate of each teiulril movement
— includiiin' thi>se just iiiveu — we lind ilu" . obtained under an averaiiv temperature of
272 v.: while the waves of rapid movement in the same teiulrils, but of less amplitude,
were i)ropai;ated under an average temperature of 21.8 V. Of the thirteen maxima of
movement obtained, one was found to be coincident with the absolute maximum of
temperature. This, howevi-r, was a movement at the low rate of O.S;') cm. per minute.
Three were found to occur on an iiiereasiiu;' temjierature. usually several hours before the
maximum was reached ; and nine were observed on a descendinii' temperature, from two
to six hours after the maximum for the day had passed

Passing to the condition of the atmosphere in other respet'ts, we lind that the
maximum movements in tendrils 1, sh. Sc and '' were readied under eouditious of great

■Soc. IV., ISSO. ','.

S'!

It «?:;3

66

rKNlIAI.I.oW ON MIXMIANISM

'a

M "'

I.M

I 1 '

^1

i;

^1
ll

i

jl

if -f

1

1

humidity; oT :ill ilu' rciniiiiiiliT, ulu'ii tlif sky \Viis dear and tlic sun briglil. TluM-att's
of raovomont in l!n' lour tcndril.s junI iiicntioMt'd were rospcctivfly I'.Ot!, (».(l."i, iJ.t; and 'J. 17
cm., and Wfrc nttaiiicd win-n. (nvini;- to tli.' liuiiiidity of the air, transpiration was not
A'ery activt'. Tendrils -2. '■'>. \. .">'/. 7". /' and f<<i uavc ri'sp(>ctivoly 1.7<i, 3. ;");'>, O.S"). 1.4 1,
O.'.'i, O.")")"! and 1.2 as the maximnm of motion. These rates weri' all reaehed while
transi)irntion was exeessive, and tlie eli'eit of tiiis upon tiie plants so great that all the
leaves, flowers and Imils were drooping!. Tendrils ."> A, c and t'w/. /', in whieh the highest
maxima wt^re reached, iiave respect ivelv \.i'>'< and tl -Ht cm., hut these rates were reached
under conditions of active. tiioULih not excessive, transpiration, clear sky and bright sun,
and while the jdant was in a normally active condition, as shown hy the erect leaves and
hue healthy color of all the pi\rts.

MlNiMt'M R.VTt: OK 'MnvK'MK.XT. — Of tin- thirteen minimum movements recorded, we
iiud that live occurred hi'iwi'cii sunset and midnight, two between midnight and sunrise,
throe between 10 a.m. and 1 p.ni . and three between 1 and 4 p.m. We further iind that
four oci nrred during a miMimiun temperature ; four just before the maximum : two just
after, and three at the very time of maximum.

As in our pre\ ions division, takiuLi' the iiijures obtained for Cui,l>, 8, 5/»,c, 1, Xc and !t
as represent iuii' the true minima for the entire nu)vement of each tendril, we Iiud
the average temperature at which these movements occurred to be 22.!' C, while the
averau'e temperature for the whoh' ihiiteen is found to be 2'>.S ('. The remaining seven
movements of irreaier rajndity were lound uiuler the inlluence of an average temperature
of 28.2 C The followiuL; able will show ilie connection between temperature and rate
of movement, as just explained : —

M ax ill mi] 1 iiH.voiiHiil.-i i:',

.Miiiiinum " l;;

.Maxiiiiiiiii " (1/ 1 r:i]iiil. ... c,

1 1'} .slcm 7

MiniiiiiiiM " I'l^ slciw (i

CO rapi.l 7

L'c, .."i"' Ml ail 'ri'iii|KTalMn'.
■J.'i . s " "

■'7.11' " "

•J 1 . s
._)._>,,' ..

From this it will ai>pear that a higher temi)erature is favorable to the more rapid
movements, to a i^reater activity of the whole plant.

Keferring to the atmospheric ((inditions, it is lliund that tendrils (!«,'> and I li'ave
their minima of movement durin<i- pleasant weather, while the plant was apparently in
an active condition. The rat.'s per minute were .047 and 0.21 cm. respectively. Ten-
drils ~ h, 0, oA, caiul s gave O.'iS. 0.02, 0,04;i and 0.01:1 cni. respei tivtdy, durinu" a time
of great moisluie and even rain; Xr gave 0.02.") cm., during the time of a heavy fog and
cold east wind. The remainder. 4, 'a, 2, 8ft, S^/ and 5 «. gave respectively O.o;il, o.0')3,
0.18, O.lo, o.1()(; nnd 0,1;! cm., at a time when transpiration was excessive, as shown by
shown 1)y the drooping leaves and terminals, and always during a very bright sun.

Dextkousk AM) SiNisTROHSE MovE.MENTs.— The circuumutations of the tendril tip

OF ArOVKMKNT IN I'LANTS.

67

may comtncnco in a dimtion with tli.' s\iii, or llui ivvitsc Movoment in fithfv (liroctiou
is by no moans continni'd duriim- the (Mitin- period of aitivily. Motion in ono direction
may soon be su.'ceeded by niuv.'iiiciu in llic other direction, one idternalin,<>' witli the
other constantly. Tiie dextrorse inotiiin, I'ov jdl the ohscrvatiDUs taken, aii'ti'regatcd 1022. ID
cm., the sinistrorse amounted to 1 Inn.!).") ,in., and the ratio of one to the otlier was,
therefore, as I to O.i^tl.

While this shows a tendency to equality of movement in the two directions — a ten-
dency which might haA'e 1)ecn more pronounced had the observations embraced all the
movements — an important relation bearing upon this point is to be observed between the
latitudes and departures of movements. Also, the relation whicli these two directions of
motion bear to one another must obviously l)e directly related to the location of the bands
of more active tissue which induce the motion. The following table will exhit)it the total
latitudes and departures for all the tendrils : —

Ti'iiilrils.

Ne. 1.

I.atituil

•t.

.") II , 4:1. H7 \

.-) '., -• LMl.sn I

.; <,,/,.

( (( ■
7 '...
S ((.

s /,.
s '■.
;) . . .

rjl.:;ii

.'):;. Jo

fj:i.:l.-.

L'l .III)
L's.-. , 1 7
I41.7.-P

]ic']i;ii'turi's. liiitii's.

:'.;ks,.Vi

S7 7.-, ^
47.7.-. j

lOi;.:;u

I

">:i.-.'(i j

Tntuls ,

Moiiiis .

l-.'L'.4n

I l!i;i.S7
II1.S4

I'JL'.SII )

i;!i.:;o )

L'ci4.7Ml

1
L'(i:;.(i;{ |

I
14 I.. ".(I I

■J4;i 711 \

IM lid 1

■J(i'.i.4li 1

ce.s:; 1

4^'.i.ii."i 1

L'lid.or) 1

LVilMll I

; L'.el
: J.r.i
: --Mil

: L'.s'.l

: 1.71

: J .SS
: \M'i

t;i:.'.L':i 1 : 1'.iiii

lis. I.". 1 : o.'.i5

•.M4."i.LM

; is8.o'.j

1 : -.'.(^

An inspection of this table at once exhil)iis a most striking relation between latitudes
and departiires of motion. AVhile in some cases Iheie is a marked variation in the results,
e.g., Nos. 4 and !», yet these, as already seen, were tendrils which were only partially
observed, and if we consider the mean result, whi.'h agrees with specilic cases in which
the entire action of the tendril was iu)led. we iind the departures of motion to be just
twice the latitudes. This indicali's most conclusively, therefore, that the principal energy
of cir.'umuutation must b.^ developed along the two sides of the tendril arm, and reference
to our ligures, as also the description of tli.> histological el(>ments, will at oiu-e show that
it bears a most important relation to the three bands of vibrogen tissue.

: ■ ^ '•

*

ai

S, uil

!= 1.

|.''«i

1

!'i

Ml

i

68

1' i:\II ALLOW ON MKCMANISM

('i>N('l,I'<IiiV.

^Vo may now innrcrd lo sum up the rom lu>i()us whiili llic loivjjoing lints appciir to
justiiy.

Tp:m1'KPATT'I!K. — Tlit> oLsorvations here n'cordod nro in harmony witli the views
irt'Ui'rallv liohl. that Avithiu icrtain limits and roiulitious. othiTwisf t'avorahli', hiLiln'r
ti'inpci'i'.tui'i's induii' moii' rapid Linnvlh. Aicordinii' to the t'xpi'rinnMils oj' Sa^hs ujidu lln'
iicrniinatinii' sfcds of Cuiurhila, ihi' niosl rapiil Lirowtli o. .urn'd uinlcr tin' inlluciuc of a
Icmpcraturc of ."loT (' : tlic > oiidilioii, ilotihllcss, hcini;' such that tiic normal IcMsion of
parts A\ as fullv mainlaiiii'd lludU'jhout, or sulijii l to hut sliuhf variations. In our own
ohscrvatious. ilir u'n'ati'st iirowih. as rciniscniid in tendril niovcmi'nl, (irrurrrd \imh'r a
ti'mi)t>raturc of J4.4"' C. : whilr iln' most rapid irrowth of iln- vino ociurri'd when thr
ti'mjifraturc raniifil from "J!' ('. to .St! »! . It is important, howovcr, not to loso siii'ht of the
fact that in these cases, there were important inodifyinii' inllui'nccs which would alli'ci
lirowth tliroUL''h the normal tension of ilie tissues. — a dislurhance of which iivcpiently
oc( urs as a result of hiiih temj)erat\ires. Tlie e-eneral ellt'ct oi temjierature hcionies
conspicuoiis at oinc, if we cum]iare the erowth for an even number of hours when the
tempeiature is above 30 ('.. with ti'rowth lor the same period when the thermal rani^e is
from :2"> ('. to ;10 . We shall then liiid the uiowth in the latter casi- to be n'reater, as thi'
followinii' tabh' will show:-—

.ViiiuImt of
o|i-ir\ati(.Iif

.■Vvi-nik'r
'I'ttiil'friitnrf.

T..l:ll iMMWlll.

li

L'T.ie f.
34.!'

U'.e ill.
1 .11 in.

.\viT;iirr tir»'Wi!i i ■, . .■ ■• i .
iMT liiMir Iti'laln.' Iliiiiiii|ii>.

II. :(:>;< in. Itdalivcly ;.'ri':it.

e.'Jiii'i in. Kclativi'lv sniall.

Ill t

The relative humidity of the atmosj)here. or the dee-ret' of saturation (h'pendi'iit upnii
temperat\ire. exerts a direct induence upon > omlitions of tension in growiim" jtarts. ami
coiise(piently upon C'rowth itself, by iiidu< in-^- more or less rapid transpiration. l']xcessi\e
humidity is consistent with mon' rapid "rowth. We may, therelbre, realiirm the alread\
accei)ted principle that increa-ini;- temperature luomotes growth, so long as it doe.^ net
disturb the normal condition.s of tension.

LliillT. — Alternations of day and niirht cause a marked inlluence ui)on and variations
in the pheiiouK'na of growth. I.,ieht is generallv accepti'd as exert inu; a retardine' inlhi-
iliiouce upon growth,' and other conditions being e(iual. we slnnUd naturally ex])ect to li'ad
the greatest elongation of the axis and most rapid movement of motile parts durine- ih,.
hours between .'iun.set and sunrise.

From the exi)eriments now under consideration, we liiul that the growth duriuL!
hours of darknes.s was in reality less tluui that, ilurinii' an ('(pud number of hours el

' S;u'li>' TfXt-licKik, 7."..^.

OF .\I(»\ KMKNT IN PLANTS.

69

(layliuflil, siiiii'. in llic < nsf t,i' \\\v tt'iidiil.-

Ihi' <hiy, iiiiiiiiDst .".:!•;. !»i) tor tli.' iiii-lit, and in lli
(lav. auiiiiist .ll.-JsT lor ili,. uiolii.

s. \vt' ohtaiiiiMl a movt'iucut of |;i.V.t,iMi ,iii , I

rrow 1

• r til

t' vine

U.J4

I (111.

or
•r till'

l>au\V('iihoti' round thai ll

.■><!. !• p. c. ol' the whole, and only V-] p. .• lor tl

If u:ro\vlh ill Ciinirhila /tcjin. lor twdv.' hours ol' dav,

was

giviiiu' ii ratio I : I.;!:" in favor t>f Ih.' former. On

w saiiii' nuiiihfr of liouis of night, Ihu.s

aro in sonicwhat strikiiii;' ronlirinalion of Ihi.s, sin

favor of day liiihl. In the casr of the tnidrils. ti

which ohtaiii durinir lh<' day ln'conirs t-vcn nioiv apparent. Tl

r results in the urowth of the v

(leriVe(

1 1

inc

ee, as .seen, our ratio is as 1 : l.'J'.t in
le .superior inlluenee of eonditions

le one eollrlusion to !»(■

roni

tl

lese facts appears to he, that the sui)erior inllueiiee of * 'inperature in

proinoliiig urowth overcomes the le.v.ser and retardiim- inlluei
l>v liirhl.

ire

whi.h may he exerted

l'"rom our previous considerations, it is clear that the movement of the tendril is but
a normal manifestation of urowth, and therefore subject to the same inlluences as other
vital phenomena. These movements have l)een found to occur in well delined waves of
greater and less activity, whi( h. u.Mially longer and of slower movement at the outset,

auvaiicino age up to a certain period.

are of decreasing leiinth and greater activity with
This, however, is soon reached, and beyond this point the movements become somewhat
longer, but more especially slower, with greater maturity. So lonu as all the tissues
remain soft and in an actively growing condition, these waves will succeed on

e ai.otlier

the

ill accordance with the controlling inll

ileiice already spoUi'ii oi

)Ut as there is an

dvaiict^ in a<;e with

yeni

■ral hardeiiiim' of the ti

ssues ai

id f

irm' iorination ol

bast.

noticeable and general leniitheiiiiiii' ol' the waves ensues. The tip mav even drop toward
the ground, as if exhaiisti-d, and not resume its nutations for one or even two hours.
When it does, it is gouorully with a more sluggish action.

' «■!

GiiowTlI IN Lenotii. — From previous considerations, it is clear that most rapid
eloniiation and most active iiKneinent in the tendril, are simultaneous and directly cor-
related throughout the entire i)eriod of movement. It is, therefore, to this very rapid
elongation in the lirst instance that we must look for a true explanation of the circum-
nutation. < )m the other hand, the structure of the tendril, presenting, as it does, a
diversity of tissues, at once points to tlie fact that this rapid extension cannot be partaken
of by all the tissues in ecpial degree. The vascular elements are those in which the least
extension can occur of all the tissues present. "With reference to all the other tissues,
therefore, they must be brouuht into a state of po.sitive tension which continually
increases in strength as aac advances and the constituent cells become more strongly
inodilied. In the colleiichyma also, while capable of greater extension and variation of
tension than the wood and I: ist cells, yet with reference to tlu' iinmodilied fundamental
structure in active arowth, there must be a well-pronounced positive tension. This fact
is at once demonstrated l)y the changes which i'ollow^ the cutting of sections. Transverse
sections quickly bulge out in the centre with a strong marginal contraction. Longitudinal
sections sliow^ a srrong curvature with the concavity on the side along which the colleu-
chyma lies. We may also, donbtlo.ss, ascribe a certain amount of this contraction to the
ell'ect of irritation, which causes a loss of water within the allected area, and thus, through
condensation, a further im'roase of tension. This is essentially the view held by Sachs

;ij

70

I'KNIIALT-oW ON MIXMI.WI.'^M

■<li u

l;r

(p. sti'.O and it rcitaiiily api'i ars justilinl. \Vi' imisf. Il»<'if|'(»ri', ic^ianl llic collcnchyiua iml
«)iily as inlliiciniiiL; all the iii(.\ fiiit'iits (Icpi'iuli'iil upon utow (h, 1»ul also as tliat particular
tisMii' wliirli rlii(ll\ (li'iiriiiiiii'x all iiio\ , nn'iit laii.si'd l»y iiicthaiiifal irritation, a vi<'\v
which is well -ui)p(iricil hv its picsriii r in the Iciidrils of Vilis, Aniptdopsis, ('(iciirhita.
Sicyos and oihcr vines, and the relations which il then- hcai> to the movements ol' those
tendrils

The nnmodiiied jniidaniental tissue, i ousisiint;' of larye. rouudt'd. thin-\vali*>d cells
filled Willi protoplasm an<l chlorophyll, is that in which the most rapid, u'eneral and
ionlinuo\is iiicrea.se or( iiis. As the central or i>ith rt'jrioii early loses its power ol'
un-owth and shrinks away radially, it may he rei;;irded as havinii' no special value in the
movements, and we must look in this rospect entirely to ihat parenchyma w iiich lies
wiihoiu the wood zone. In all of the parenchyma tissue (I'lale IV. Kit;. 1) at r and a. there
is found to he ihe greatest aitivity: and this power of extension is so stnnm'ly developed,
that even alter the \asi ular elements have assumed their most liiiiiilied condition, and the
tendril has permanently coiled up. the viln'ouen tissue at n a will lie found to retain its
activity lor some days. Wi' must, therefore, infer, from this that the neirative tension, as
a whole, is developed most stroimly in the parenchyma tissue, and particularly in the
three l)ands of vihroucn which lie at n n <i."

Ti^Ksio.N. — Sachs' distinctly states that no torsions occur in Cuc\ir1>itaco:i'. This is not
conlirmed by our ow n observations, however, since it has heeii observed to l)e a c'tmiiion
feature of the circumnuiations. that disiimt torsions constantly occur. This is readily
determined, not only hy the vihroecn hands, hut hy the chani;es in the direction of the
recurved lip. Similar torsion is .also readily dete.ted in ihe iietioles of both tendril and
leaf, and that it bears a most important relation to the circumnutatioii itstdfcan hardly
1)0 doubted. So strongly are these torsions develop.'d in the temlril arm, that the tip
fre(juently rotates throii-h Isn or inn . The explanation of this torsion is not dillicult, and
has b.'cii niven on many previous orcasioiis by various (d)servers. From what has already
ajipeared with relerein.- to the various lissu.'s in their mutual relations of position and
tension, it is dear that torsion must follnw as a natural restili of excessive tdontration in
the external layers, thereby exertinii' a positive tension upon tho.se which are, internal.

m

lRRlT\ri<i\. — ( )1 the two sides of the tendril arm, that which is uppermost and
slightly channeled is the least sensitive to contact. This bears a direct relation to the
distribution of the c(,ll,.nehyma tissue, whi( h we lind to be more continuous and Htronyly
develoj)ed on the lower and sensitive side. 'J'hat the vibrou'en tissue is not concerned in
chanires due to irritation, ap])ears evident from the fact that the liexure never coincides
with these baiuls, but is always toward the lower si(h' of the tendril arm, conformini;- to
the position of the col|,.neh\iiia. The concliisi(.n is justiflal)le, therefore, that the laillen-
chyma tissue is that which is dir.'ctly comerned in such movemont.s, throug'h its capacity
for stronu' variations in the contained water.

A tendril subjected to local irritation for about thirty se<onds, dev»'lops an a}»rupt
(urvatiue at that point within one or two minutes, and the bonding continues so long as

Tuxt-licKik, SCii;.

<»!• MdVKMKNT IN I'LA.NT.S.

<»|- MdVKMKNT IN I'LA.NT.S. 71

ll... for.-in.,, |M„ly is i„ , o„|;n I, „n,| .'VM lor ,•. f.-W S.-ouds l.ri.r it.S IVMK.Val |'u,„huv

with u pin. ur III.- ii(li.,u or i, I,,.,,, ..rCnva.l.pr.Mlucv.s .similar HH., Is. Initiilioi, ovr immoiv
.•xlni.lr.l iuva raii.srs a .orivspoiuliiiu'ly lar^.-r .•luvatuiv. TImt.. i> mo .spr.ial .•\ i.i.-ii.r i,,
such .a.s.-s thai ihc impiils.. has h.vii .•oinvy.'.l l„.yoiMl ll..' liiuits of il,,, aiva irritat.^l,
and soon allrrth- inilaiH 1h„Iv i> ivmovci - th.. -rou th in I hr various li.ss.i.s hauiio'
h.'.'(.ni.- i>Ta.liiall\ rrslonMlo its noniial roiMliiio„-i |„. i,.,ulril sirainhi..„s ,,,11 and on."
more rcsiinii's its rirriinnnitatioiis.

Moiv viol. -Ill ni.'.haMJc al siinuili proiln. lili;.r.'ni .•lin t, howov.T. .V sliarp Mow,

su.h as would !>.' uiv.Mi l.\ a |M-nril, iallin- upon aiiv part o!' Hi,, arm, i>ni(hi.vs an cH'.-.t
whi.'h throws th.- lalirr into a si^rirs oj' loni-' nn. Inlatioiis |;,r iis mlirc j.-nuth I'loloni-vd
irritation at the lip will usually produrr ih,. sanii' clHTt. Tlh-s.- la. is at on.,, and dirrdly

point to th." inf.Mvn.'.' that, whil.' ll H...! is slowly i)rodu.f(l. ih,.r.. is. n..v.rlli..l..ss, a

distim t Iraiisniissioii ol impulse to very r.'mol.. parts. ^V(•r^• .'on.-us-ion alon.' . <.n.rrn.'(l,
il miiiht be possihlc to rdrr the whol.. rhaniiv to it alon.'. as ilir.'.lly alle.iinLi Ih.' luruiditv
of the .•olleMrhyiiia tissue: hut ill.' la.! that pr..loiMj..d irrilaliou will pro<lu.-e a sin '
result, should rai.s.' a ipiestion on ihis poim. IVoiu w hai \\e now know . on, .■rnin<>'
st'U-''ivi' nature of p.otoplasm, the relation wlii.h this suhslan.e hears lo Limwlli
turisidity, and ils now well estahlished ciiitiiiuity Ihrouiih living' tissues, are w.'
justilied in the heliei" that sueh transmissions as ahove not.d are prinnirily propayi
thr<)ui{h this moans j"

■erneil

iility
similar

the

in<l

ClKri'M.M'TATliiN, — Our attention is lirsl ol' all .alL-d 10 the I'aet poinl.d ,.ul hy
Darwin.' and conlirnied hy our own ol>s,'rviitions, that lli.- " l.'ndrils revo'i\e l)\ ihe
eurvalureol' their whole liMiuth, I'.xceptin.^- the seiisiliv.' .'.Mreniil v and the hase. wlu.h
parts do not move, or mov,- l>ul little." This . 1,'arly shows ihal whaf.'Vi'r ion.' is in
operation, aits unilornily through ihe entire lonuth of th,. molile oi^an. and that ihe
movoment has not a local origin al or near ih.' has.. We must, iherelor.'. ron.eive,
as hotli Darwin" and Saehs' exi)lain, that iher.' is a lon^iiudinal hand of mor.' actively
i^rowing tissue which extends Ironi has,, to tip, and thus the arm is h,.nl ov,.r toward the
Hide ol' h'.ss active lirowlh. ."^o I'ar. our own ohservalions are in siri, I harmony with these
views, hut they do not ac.ord with the , .pinion thai ih.'s,. hands ■"ira\,l rouinllh.' I.'inlril
and successively how each part lo the opposite sid.-." -As already shown, the li'^ure
described is not one ol' ri'i'ular progression ihrough successive points olan ellipse or other
li<;ure. (See Plate III.) In I'act, the tip may change its direction v.'ry abruptly, ol'ten
retracing the path just passed over (Nos. :!»;, oT and ^IS), or the chang.' may he less abrupt.
While, therel'ore, it appears from the ueneral e(|uality ol'dextroise and sinistrorsi- movement,
that the totality of motion in one direction must h,' compensated by an ecpial mov.'meiit
in the opposit.- direction, the facts citetl show (piitc .-on, lusiv,'ly thai the b;iiid of growth
does not pass regularly through siu'cessiv,' points in Ih.' cinumfereii.'e. Iml tl:at it arises
irre<>-ularlv. .■\"'ain. the relations of the lissu.'s in their mutual tension, and (he i)ositi()n
whitdi the vibrogen tissue occupies, inoiv i.sp.vially the rclalion whi.h this latter bears
to the latitudes and departures of movement as already pointed out in a precding
paragraph, serve as a most important indication of ihe true position occupied by the bauds

Clinil.iiiu' I'liiiit.s. 17e.

/'././.

Tc\l-lM.(,k.

m

! HI'

<\^

■ < Ul

'11 t:.\m
1 hm

72

I'KXIIALI.OW ON MIXMIANMSM

hi

mk^

of ijrowtli ; and tlio coiiviition Ikmoiiics more lirmly iinprt's.scd uiioii us that this position
is ViOt only Hxfd. hut that it toiniiths witii llic vihroiii'U baiuls.

Aci'ordinij- to this view, all uiovcmi'ut would he pviniarily du(> to these three hands,
su]>pleniented by less vifjorous iiiowth in tlie inteiniediate tissues. Therel'oi-e, all depi.i-
lures of motion would arise prinuirily i'nun the two vihroijen hands iraversiui^' the sides
of the tendril, and all latitudes ol' motion would he due to tiiat. vil)ro<>-en traversinir the
upper si<le of tlie tendril arm Any deviation from sirietly lateral or vertiial oscillations
must then arise as resullaiits of aetivily, either between two vibrou'en bands, or between
oiu' vibrou;en band and inti'rmediate tissue of slower lirowth. I'inally, the torsion already
shown is to he regarded as ha\ ing its origin in. and as eonipeiisating exeessive growth in,
one or all of the vihrogt'ii hands of tissue.

B".;:r i

Kih(,

vn ■.

m

SPASMCinic ^I(i\KMKN r. — It has been nnted that towards the end of the einumnuta-
tions, periods ol rest alternate with periods <if activity ; that the whole action lacks vigoi;
and that iheie is a failure to ai complish those i^-rand sweeps which are .-o conspicuous in
thi' earlier period of i"tivity.

Those I'eatures are uiiilout)tedl\ to be relerred to gradually increasing liii'nilicat ion in
the wood and bast cells, ainl the niodilied conditions of tension which necessarily result
from this. .As the bast cells, particularly, increase in thickness, their degree o|' resistance
or of positive tension correspoudiuiily increases, while at the same tinu' the growth of the
jiareuchyma tissues continues at a lU'arly unilorm lale, So loni"' as the bast remains thin-
walled aiul capable of its maximum extiMision or response to (onditioiis of external
tension, for such period is the normal relation between it and the more actively Lin'wini:'
tissue preserved, and this is marked bv rcLiularit v and rapidity of motion in the win

organ. With exi essive disturl)ance of the normal ndations. th luilibrium isdisturl

in the direction of the more resistinii' .■structure, and this linds exi)ression, lirst of all ii
slow and spasmodic moveuieiit. and linally in the completion of the spiral, wliich i:
always developed freely, without lonlail. at the end of the period of ( inumnutation.

>lc
,c,l

i:i

■ -c * ' '

m ^

Coii.lNd .MiOVT \ f^ri'l'oi.'T.— Coilinu' about an object with which the tendril comes in
contact, has already been discussed indircitK. thouii-h it mav be well to nd'er to one oi'
two facts metre particularly. The coilinu' of the tendril tij) about the point of contait, i.>
the direct result of irritation, as both Sachs and jlarwin have alrea<lv shown, and as the
latter' exi)lains. it i- developed by a sliorii'iiine- ol' the side in contact with the oliject. the
same change, i.i'.. condeiisatioii ol .•-iru' tuie and reiea.se of ti'iision. oi)eratinii' here as in
previous cases; ami with Darwin, we can hardly a^rree with Sachs.' that the coiline i> m
any way due to accelerated n-rowth in the unirritated side.

A\ hen ome ufrowth in lenL-'th is arri'ste<l. as it ajipears to be soon after coiline is
elfectcd, the rapid hard.iiiiiL;' of all the parts ai)pears to be the prevailinii' cliaiie'e in thi-.
howevi'r, it is diin<ult to couci'ive that the mechanical irritation has produced more than
a very limited eliec t in advaiicitui' maturity. On iIk' other hand, it rather appears that
each tendril arm has a normal ]»eriod of t-rowth. which i- <(inipleted only when the won.l
and bast (dls have reached their lull dei>ree of maturity, if at the end of this i)erio<l the

Cliinliin/ riantH, Isl.

ToNt-lienk. Sllll.

m

OF MOVKMKXT IN PLANTS.

78

tondril fails to secure (■(lulmf willi a suitable object, it coils up IVeolv, as already sliowu,
and this is tiie necessary conse(|uence oi' the normal clianii'es in the tissues. II', however,
it comes in contact with an object oi' suppnrl. the tendril coils about it and ai-iomplishes
its double spiral williin tlic normal period oi' its i^'rowih. This pmiod cannot be
imdoiijred for the purpose of lindinii' a suitable support or completinii- imperfect clianu'es.
Tliesi' must all be aicomplished before tlie wood and bast lissui' — the latter in particular —
reach a certain sialic in tiie deveioiimeni of tlieir pi'rnianent I'haracter. This is well
shown in the fact that old tendrils, wiiich have failed to 'arasp a support until very near
the end ol' their activity, manifest a strikinti- loss ol sensitiveness, and often catch hold but
imperi'oi'tly, or if they g'aiu a lirm liold, fail to perft ct their doidde spiral.

II. — Yrviri ('oi;i)iixii,i\. iMirlix.

In the tendril of Vitis. not oidy with reference to its sensitiveness and o-euera! cir-
cumuutations, l)\it nmrc es])i'cially in its histoloLiicid aspects, we Iiave to deal with an
or<>-au which presents many features distinct from tiiose of ( 'ucurbila. the common i^-rouud
of resemblance Iteini;- found in functional similarity and in tiie way in which the circum-
nutalions arise.

The tendril of the urajie is a modiiied l)raniii. beariiu>' two smaller branclies which
serv*' a similar purjiose. These brandies, however, unlike those of the Cucuibita tendril,
do not proceed Irom a lonnnon point of insertion, but arise successively on the elongating
l)rimary axis of the tendril as a whoK>. In their external aspects, they are well rounded,
but somev/hat ihittened on the inner face toward the extremity, where the tip is strongly
recurved. Throughout lln-ir lenglii. the prevailing red color ( I'. 'V)/v///i)/A?) is broken by
ten narrow uiveii linos, which are developed at approximately e(|ual distances through
tlie circumlVrence. These are the bands oi' vibrogeu corresponding tu the three bauds iu
the tendril of Cucnrbita. Internally, the stru.'ture presents tin' features exhibited iu
riate V. l'"igs. 1, 2. o and -I v — durinu' the earliest period of circumnutation— from which
the followiiui' details may be gathered. Tlie epidermis consists o( a siimle row of thin
walled .'ells with a strongly corruunted .uticle. Dire.tly beneath this, lies a single row
of |)igment cells .•outaining tin' red coloriii-- matter. The hypodermal tissue .onsists
chiellv of .•olleiichyma. iu whicb the angles are but sliu'hlly thickvned (Fig. ■]). As a
whole, the tissue i.s (juile coi'tiiiuous in most cases (Fig. 1. rl). Within the r.'don of the
hypoderma lie the ten vil)rogen bundles, <-, r. r. etc.. which ar.' woU deiined from the
surrouudin-j- tissue, but somewhat variable in. size These bands, altl-.ouu'h they fre-
(pieutly penetrate the collciichynui .lei-ply. do not always break its continuity. Next^
witliin the collenciiyma is a i lin layer of v<'ry active fuiulamental tissue, the cells of
which are laruv and regular (Fiu' 1./'/). H is within this tis.sue that, at a .somewhat
later [.erio.l, the cambium arises as a well dcHued layer. Directly internal to this is the
wood /one. or xvlem portion of the vascular bundles. This, in the .'arliesl periods of
cir.'nmnutaii.m. "is comimscd of sonicwiial i.M.lat.'d and nascent va.scular bundles, the
I'lementsof which are all very thin wall.'d and rai)idly in.'reasing (Fig. 4.\). The only
structural elenvnt remainint;- is the pith, whh'h.as iu fucurbita, boars no spooial rolatious
to Iho circumuiua; i'jus.

Sw. IV., ISsii. 1(1.

1^'!

ill

m

74

I'KNIIALLOAV ON MKCII ANISM

i;.>i.

i' ■ m

■t I vi

■t'

1 : ,

lli . «

J 1 ...

As th(> tciulril iidvanci's in aiif, M'vfViil iiiipoitaiit fstnictural tliiiimfs occur. The
whole hvpodonnal tissue increases slii>'litly in thickness, and sinmltaneously tlie tissue in
the reu-ion of each vihrou'en hand. an<l lor the lull deptli of the /one, c/, heconies so niodilied
that the coniiioneni cells enlarii-e slroiiLily — chielly in a tanii'ential direction — while tliev
also hecoine niucii more thin walled, and ail Ira^ cs of <-ollenchyinatous thickeninn' dis-
appear. This causes a stroni:' localizatior ol the . oUciichynia to the reii'ions l)etween the
vihrou'en hands, wliere it retains its oriuiiuil iharai ter (i'"iu:. :'>) without much diauiic
lievond an increase in llic size of ihe < dls. Within the reii'ion, //;• (I'lR- 1). tln't'e arises a
layer ol' camhiuiii which Ic.rms a continuous zone. Imoui tliis arise hast bundles, one lor
each ol' the vascular hundles already noted. The former remain ([uite distinct to the .'ud
of their i^rowth. aiul are usuallv widely >ei>arated. I'rom the inner lace of the camhiuni
tissue, there arise new wood cells, wiiich now heconie devidcped so uenerallyas to render
the oriii'inal bundle.^ conjunctive, thus Liivinu' rise to a continuous zone of wood wliich
continually increases in thickness.

At a verv early jH-riod in its liTowth. each va.scular l)undle devolojis from two to threi'
vessi'ls and ducts. ITtinnitcly, all (he lihrous elements liecame hiiihly liunilied (Fiir. 4 li)
That this londition may lie hastened in tune, and possihly increased hy contact, cmii
hardly liedouhtcd; hut it i.-- c(|uallv true tlial such c]iani;es occur normally where there
is no (ontact, e u'., ilie section.^ here exiiihited w>'re taken i'lom a fretdy < oiled teiulril.

in coniparint;- the tendrils of Vilis with those of Cucurhita, several important struc-
tural dillerences beccnue apparent. The much iirea ter number of vibrouen l)aiuls in thi
former, and their somewhat rcLiular distrilmiion. at once sue'tre.st greater re<fularity in tlie
iiyure described, as well as a ucuerai e<jualiiv of motion in all directions. Also iu Vitis.
the inferior developnieiit of ilie colleuclivma is coiisi>tent with, and may serve as a proper
explanation of. ihe mu. h lower decree of sensitivene.s.s there numifested. While ihi
general changes incident lo maturity of parts are the same in any case, it is not(>worih\
that in Viiis there i.- no distinct zone of bast which I'ullills tlie function of that tissue in
('U( urbita. and ui)oii tiic x\ lem jiortiou of the yaseular bundles must depentl that resisi-
aiice to general eioiii;ation wlii.li i.'s .so essential a factor in cin umnutations ; thonali
undoubtedly, in ihi.s < ase. uiiecjual niowih of oppo-ite sides is of I'ar greater im])ortance
than iine(jual ii iision of component tissues, so thai torsion would here be of less value as a
factor, than in Cucurhita where it is generally mor>' marked.

Durinu- the circumnutations, distimt torsions occur. These are readily delerniined l)\
trai iuii' the . (lurse of ilie yibroii'eii bands, from whic h it bcconu's apparent that the tendiil
is fiecjuenily iwist.'d to the extent of oue-hall ' XDlutioii upon its own axis. 11' no object
is urasped during;' the active iieriocl, the tendiil ultimately coils upon itself; but Iiavinu
gras|)ed an (pbje, t, it iterfects a double spiral similar to that in ('ucurbita. It is also noted
that tendrils ^yhich ' a\e coiled freely, do not beronie so hard and drv as those which ha\e
secured ;ittarhmeiit. from whirh it v, ould appear probable that « onta( t jiroduces a nu)ri- or
less marked elie< t in ac( eleratiim. or. at h^ast. in iiureasinir the maturity and slri'iiLilhof
parts, a view which gains stroiit;- coniirnnition also from the very marked dill'ereiK cs iii
these resj)i>cts to be found in Ampelopsis.'

It would thus tippear that the general lealures of circumnutatioii in Vilis and Cuciir-

liaruiii, ( liiiiliiiin riaut.s, Ms,

OF .move.mi:nt in plants.

78

bita am tl.o sanio, and that thoy may b.Mv-av(l.><l as ivpmsontiu- a particular .lass ol'
movomcnts, .so I'ar as (hrir mn,l.. ol' pnKlurtion, as uvll as tlu-ir avnoral oxtornal Toaturos
aro .•on.-orn..,!. It ,s not as yt possil.i.. to sav iiow Tar .-arh of tlu-so niav n-pr.-s.nt th.'
type lor tl„. lannly : hnt IVo,,, ll„. similarity ..I' tli- strmtur.. and .•ir.T.mnutation pn'scntc'd
l>y M.-yos and'oth..r('u..urhita.vous vines, it is p.-rhaps s;db to inlVr tiiat. in that case
('iu'url)ita IS thr f yp.- ol' the family.

The deductions which the picvdiim- Iih^Is justify arc as follows :—

1. Movements of circumnutation arise ihrou^li umniual u'rowtli of tlie tissues, which
is (hielly reiircscnted hy tlic vihroiivii haiuls,

2. The bands of more active iirowih arc strictly localized.

•5. Movements dm' to irritation <l,'pend upon continued eloni-'alion of the opposite
side, to.nvther with .essation of <>-rowlh and .ontraclion in the irritated i)arts.

4. The coUenchyma tissue i.s that whidi is chieily concerned in variations of tension
under mechanical stimuli.

- fm

III.— KoiilNIA l'SEri).VC.\CIA, L.

In the l\obinia, there is not only an entirely distinct variety of nmtion, but also a
motile organ whicli dilfcrs widely in many respects from the i)lants that we have
previously considered. In this case, the special oruan cndow.'d with motion, is the leaf,
which, instead of .scrvinu' as a i)re]ieiisili. ,»rL;iiii, is invested with the power of moven^'ut,
for rea.sons direetly conne« ted with its own preservation against sudden and extreme
atmospheric changes. Unlike tendrils, therefore, such motile leaves arc found to present
certain i)eriodic chaim'es of a most conspicuous eharacter. Tiiey are, moreover, in most
cases, supplied with a special .ushion or [)iil\ inns, throuuh which the motion is primarily
determined. As a wliole, smh movements pres.'nl a certain rehition to thos(> already
discussed, in that they may he regarded as modilicd circumiiutations.'

Pt'LVlM's OK Till-: Lkai". — Ivicli pulviiius surrounds tlie i)a>c ol its corresponding
petiole as a cushion, conspic\u)Usly hniicr beh)W than above. Ii extends u[)ward from
the point of insertion of the i)etioh', for a distance of l.a mm. to T.'i mm. its diameter is
variable, increasing;' with iiii'c of the leaf, but api)arcntly nuich nu>re dependent upori the
raniiuess of growth in the plant as a whole, since the largest pulvini are invarial)ly i'ouiul
upon rank growinu' suckers. I'mler tliesc circumstances, the diameter has been found
to vary from •'].!• mm. to ").() mm., the mean si/e l)ciiie- not far irom !.<• mm. I']ytcrnally,
with a smootli and siiining surface and very liiin llirouulinut. il iiossessesall th(> fixtures of
hiuh tension. Of uniforni si/e tlirouuhout, its strongest development is on the lower side
of the i)etioic, while al)Ove it often liut sliehlly exceeds tiie petiole itself At the base on
the lower side, just at the point of insertion, tiiere are two triaimiihir de[)ressions in the
pulvinus, formed bv three ridges, one oiwhiiji is central and stronLily dc\ eloped, while
two are lateral and less strongly delined. .\11 these ridges extend downward from the
base of the i)ulvinus for some distance on the stem, and serve an important mechanical
purpo,se, as braces or supports to the leaf. Dinu'tly interior aiul corresponding to the

I'lirwill, .MiiVrtlicUt (if I'hilils, L'Sd, etc

r::.'m

y-i'i

76

PHXirALLOW ON .MKCIIAXISM

B^'il

f; i
Ms

1'''^

ri;

J

tlcpri'ssioiis notoil, and thus ()r(Ui>yiiiL;' iln' cxlrcun' Itasc ol' the piilviuus, is a lari^'e intcr-
colllilav spare, into whi'li piiijcct iiunirnius roaisi'. straiulil, shaip-ixuiili'd and thick-Wiillcd
intercellular hairs. As seen in transverse seninn. this space lies within thf lower hall'df
the i)ulvinus. while tlie vascular stnii ture is <livided into three bundles, whidi traverse
the prnjci tiiii;- ridges rel'erred to .dxive, and thus it passes by the intercellular space on its
lower side, in the extn^nie periiiheral i)oriion ol' the pulvinus, That portion oi' the
pulvinus wliich lies on tin' ui)per side ol the intercellular space, is quite unil'orni both
extenudly and internally, and i>resents only those internal niodilicatioiis of the normal
tissues which are essential to its character as a j)ulviiius In its structural details, other
than these, the pulvinus may be characterized as i'ollows : —

The epidermis is simple, the cells ol e([ual dianieier or sliLihtly eloimated taniifutiallv :
the cuticle is thin. The hvpodcnnal tissue, which constitutes the j)ulvinus proper, and
extends, without niodiiicatioii. to the bast /one. is of the same kind throuu'hout, and
consists ol' simple, round-celled pareiicliyma. with moderately thin cell walls. The cells
show no essential variation in lonn. th()Ui:h in size Ihey are usually niiu'h tlie lariivst in
the central region. Throusxhout this tissue, continuity >!' pvotoi)lasm may be readily
determined by the methods alreaily slated. In the i eiitre of the pulvintis and completeiy
surrounded by it. is the iibro-vascnhir stru<ture whii h I'orms the base of the petiole, in
this vascular axis, the \ arious tissues ol the stem— pith, wood, cambium and bast —
may be readily distiui^uished. The pith has the outline ol' an equilateral triangle with
its Inise facing the upper side of the pulvinus. thus ((ii\ forming;' to the external ionliii\ua-
tion of the pulviiu;s as a whole, as well as to the g.'iieral outline of tin' other tissues.
The cells of the jiith are small and usually with luedium-thii k tell walls, though in some
cases, i'sj)ecially toward the base of the pulvinus, they become very thick. The wood
zone is well defined, and iumpletely em loses the pith The medullary rays are very
prominent, but the most striking feature is the ])resence of numerous pitted ducts and
Vessels, which, from their lonii- diameter, ((iiisj)icuously thi<k walls and regular radial
arrangi'meiit. at one attract notici'. .Among them, theic api^ear. in much h'ss conspicuous
manner, the wfiod cidls, \\ hiih are small both in length and breadth. Surrounding the
woo<l is a somewhat mirrow Z'lie, which, in its earlier periods of growth, is nieristematic.
and provides for radial extension of the wood zone. It possesses tin' usual charaileristics
ol such tissue. The bast Zone lonns a > ontinuous tissue. The cidls are of snndl diameter,
but very Ioul;' and fusiform. Tin' walls are of niedinm thickness and traversed by
numerous pits, which terminate at the intercellular substance. During the activity of the
pulvinus these cells are all tilled with protoplasm, and from the facility with which the
walls swell under the inlluenci of strony- sulphuric acid, the tissue i)resents one of the
best oJ>])ortunitie.^ for (pbser\ ing the c diitinuit v of i>rotoplasm. 'i"he bast, as a whole, is
i)rol)ably to be reoiiitl.'d as one of ih.' most imi»oriant mechanical eli-nieiits present.

I'rom what has i)reviously loen stated with r.fi>ren< e to the sectiomd outline of tlie
jnilvinus and its imludi d vascidar stiudure, it will be seen that the latter is not conceii-
tri<- with (he iormer, and that the minor iixis, which passes transverselv through the true
stnictnral centre, lies • onsideral)ly above the centre of the se< tion. and since this is a
constant feature of the pulvinus, it will be seen that the lower half of the transverse
section and the lower side of the puhinus always exceed the upper half or sidt-. The
relations ol parts in these respects were determined liy making an outline drawing of all

. »

OF MOVKAOiNT IN I'LANTS.

77

the parts hj nicaiis of th(

n'prfsciitiiiii- IIk* minor ,ixi

aiiicni. under a

n am

pi i flea I

tissues lying above and below
follows : —

s was then passed transvers,-lv tlir

ion ol L'O diameters

A 1

mo

ouuh the true cent

measured by means of a planimeter. Th

re, and all

le results were as

V'llOll illlll I'.ilSl I,

'ai«Micli> 111:1 (if I'lih iiiii.-i SI

I'l'Kl: Mm;.
•■■•iiS,|. nil.

i.iiui 1: SiiJi:.

l.Oll Sc|. .'III.

.'.'{.nil " "

171.1

1'

rom this it appears thai. leaviuLi' the pill

meclianical importance, whatever tensioi

to t

he tension in the surroundinii- |>ulvii

1 ahouvtiier out ol' eonsideral
I is produced ill the vascular bundle

1011. as ot no

'litre in the iiroportioii ol' 1 : l.:;i>. Since ll

Ills, must be developed

le vascular element

as oppo.sed
ibove and below the true

maiient structure, their teiisi

s are o

f th

nature ol'

on in I'

uenera

1 rel

ea^i' o

f t

region. It therefore follows that tl
)f the nulvinus in il

elation to surroundinii' parts must be posiiivi
elision must result ill a contraction of the organ throuuh th-

per-

iiid

111

y

vascular

lis coiitraitioii must be stronger along the lower side

e pulvinus in the ratio given, and hen

• lowinvan

Ills, thouuh s

liiiht.

temleiicy to curvature of the pulvi

niav often l)e noticed.

inus

The tension in the tissue of the
is developed above and below the t

puhinus. as oppo.sed to that of the vascular strurture.
rue centre in the proportion of 1 : •2A2. The pareu-

ehyma tissue of the pulvinus is that capable of th." <iieate>t and

as also that in which the greatest variation

most continued growth,
)imh

sol tl iision must occur I hrouu'h variable tui-c-es-

ceiice. its tension, with relation to the vascular striKture. must be iieii'alive; 1

lellce

lllV

ise ol tension
)ove and below

release ol tension must permit contraction of the whole oriian. while incn

must tend to eloimate the pulvinus. and this iiction will be developed al

in the ratio given, l-'rom this it is obvious that elevation and depression of the leaf, as a

whole, dei)end respectively upon the pulviiiii> inoper and the eii' losed vascular structure.

l-'rom what has thus far appeari'd. wc are (loiil)tless |)repared to uain a true expl

Illa-

tion of till' large intercellular cavity audits ext riial braces, which occur at the base of
the pulvinus. The three braces, of which the cciural has lieen seen to be the laryest. must
d(ml)tless be regarded, lirst of all, as means of mechanical support through the lirmiiess of
their striutiire ; while the })ulvinus proper, which still .-iirnmiids each, seems to control

cluiUge.s of position to a certain extent, by its v;uiable teii>iiin. The <lepression of the leaf,
under any circumstances, however, must cause a much stronucr compression of the
slructur«> on the under siile of the pulvinus, where the llexure occurs, than elsewhere;
and this is at once compensated for by the huye inteicelhilar 1 avity. which permits the
central l)race to bend into it, the leaf thereby hinginu' ( hielly upon the upper side of the

pulvinus

his view uains additional weitihl from

that, wlii

curvature may arise through tin

rh th

w

■imi h of the pulvinus,

the d

e very sli
1 th

iht

epression ol tin

is chielly accomplished by sliarj) beiidiiiL;- at the extreme base of the pulvinus. which thus

)eeoiiies the true joint 01

liiiigi

M

n \

I a

<ll

rri,\IMs Of llIK Li:aii,i:t. — The ptihiniis of the leallet bears but little external

roKemblanie to the main pulviiiu.>'

it is of uniform width, aiidextemls the entire length

f the petiolule, lieingbut sliuhtlv llatteiied alonu' the upper side. The length varies —

between leaves just unfolding and in their mature state — from .").U mm. to 0.0 mm.

78

PENH ALLOW ON MKCIIANISM

mi

;!ii

whilr for tho same period tho tliaiiu'tfr varifs from i.O min. to ^..^ mm. Those dimcii-
nioiis are ,sul)j('(t to iiuK'h less variation, as dependent upon conditions ol" growth, tliaii in
the main pulvinus. Externally, each little pulvinus is minutely and somewhat den.sely
pubescent, a character which at oiu-e distinguishes it iVom the laru'e pulvinus. Moth the
superior and inferior terminations are devoid of lateral ridires or depressions, nor is there
any intercellular .avity. In these facts, tliere appears a very stronu: art^unient in support
of the supposed me. iuniical importance of these structural features. The structure, in
all its pai^s is continuous throuii-hout, so that in most respects leluliug to their grosser
anatomy, the larirer and smaller pulvini are (|uite distinct.

In its internal structural features, the epidermis is simple and the cuticle thin. The
tissue of the pulvinus is ihe same as tliat in the large pulvinus, though not so strongly
developed as a whole, il'late V. Fig. .V) The important feature of the organ, as a whole,
is the peculiar form of aggregation of the tissues and their mutual relations. The
transverse section is nearly round, its vertical diameter exceeding its transverse in the
ratio of 1 : \AM). The wood and bast, instead of iormini;- closed zones, are ojien alouii' the
upper side, where the pith l)lends with tlie ti.ssue of tho siarrounding pulvinus. This
peculiar arrangement bears an important relation to the llexil»ility of the petiolule as a
whole, and corresponds with the fact that curvati;res of this organ are downward and
not upward. Determininii' the distribution of similar tissues, as in the previous case, with
reference to the true centre, we iind the followiiiir : —

ri

t'iii:lc S\in;. I.owki; Sihk.

\V<hm1 aiiil ISa.sl !.!• Sij. fill. (i.li S(i. lan.

I'arciicliyiiia nl I'liKinus ;>3.S " " .M.;! "

As,siirning tht> same function to these tissues in their ndations of mutual tension, as
in the case of the main i)ulviiius. it would appear that the inlluenee of the sjx'cial tissues
concerned, in promoting elevation or depression of the leailet. must bo exerted between
tho upper and tho lower side of the pulvinus in the following ratios : —

\V<in,l .dmI Hast

l'ari'Mrli\ ma

I'l'i'iii;. I,ii\vi:n.
1 ;<.47

1 l.VJ

CompariniT these valui's for those obtained in the previous case, it appears that in the
lower side of the pulvinus tlie vascular elements exert a much stronger inlluenic as a
contractile tissue, while the parenchyma exerts a much weaker iniluence as an erectile
ti-sue. IiiharmoMious with our i)reviously expressed views as this at lirst sight appear
t" be, it re.iUy olfers no ground ol conllict if we l)eiir in mind the relative size of leal
n '.illit, and tlius realize the very inferior inilueni-e of uravifation upon the latter.
'■ inteicellular cavity which app.'ared in the large pulvinus is. in the smaller organ,
1 [}.j,i d by tlu' i)eeuliar development of the vasiular structure. The open pith which
apjjoars alou'/ the upi)er side permits a iireater extension of parts in that region, as the
pulvinus ( urvcs downward.

During the period when the leallets are folded, just as they emeru'e from the bud
and for a short tiuii' afterward, they manifest no ny< titropie movement. During that

OF .movi;mi:nt in i'lants.

79

period, iill the vascular clciiients nrc in a iiasccnl stati' (Date V. V\ix. fi a). As soon,
however, as tlie Icallcts iinlblil and movenicnl Ix'gins, tlie various vascular elements arc
found to have become stronjily developed (Fig-. G h), and I'rom that time onward they
continue to incr(>ase in their character as permanent structure. It thus appears true that
no movement can occur until the woody tissue reaches a certain stai>c ol maturity.

SKNtrnvENESS. — The leaves of Kobinia are not sensitive in any marked deyTee. Inci-
sions and other strong- irritations ol' the pulvinus have, with us, produced no etlect.
Simple irritations, such as would produce an immediate cU'ect in the tendril of Cmurbita
unless very much prolonged, are also witliout eU'ect. and response appears to be gained
I'rom nothing less violent than percussion. Several determinations ol' the ell'cct of percus-
sion were made. In each case the base of thi> leaf just above tlu' pulvinus was given a
short, sharp blow with a pencil. The following results were obtained (in each case the
degrees given reiu'esent the depression of the leallets two minutes after percussion) : —

((() 10.05 A.M. — No. 1=S7'. Ni). ■_'— s7 . No. :'i=>=(iii .— Kfriipi'r:itioii (■(iiii|ili'ti' at \U:S>. — Tiiiio nMiiiireil='JO iii. —

I'laiit in sliiulc-
(/)) lo.l'J A.M. — No. I=s7'. No. •_'=r)0\ — l{('('u|i(TiUinii iMiii|il('li' al 10.:!o. — Time H'iniiiril=ls ni. — I'lant in .shade.
((■) 10.17 A.M. No. 1=50 . No. L'=»45'. — l!L'rii)«'raliiiii ciiinpli'lo at lo,;;ii. — 'I'imc nHiuiroil=i:! ni. — I'lanI in sun.
((/) lO.'JO A.M — No. 1==»=15 . No. i;=-15 -so ,— Kcriii'iTatidn i(ini|.lft(! at lo.:!l.— Time n'(|niir(l— =11 ui.— Plant in

tlu^ snii.
(<) 10.:!- A.M.— No 1=0'. No. L'=0'. No. ;i=50.— IJei'iiiK'ralion I'lmiplcte at lii.4'.'.— 'I'inic ic4nin'<l=10 m.— Plant

ill tilt' sun.
(^•)10.;!8a.m.— No. 1=-')^ . No. i;=45 . No. ;!=-15 .— U('cn|ieratinn comiilelo at 105:',.— Time reiinireii=15 ni.—

I'lant in tl^e sliaite.
{(/) 10 4'J A.M.- Nil. 1=55 . No. •_'=45 -50 . No. o=45 -00 .— lU'cujicratien cuniiilete at 10.50. — Time reqniroil=17 in.

— riant in the shade.
(h) 10.47 A.M.— No. 1-^0 . No. •_'=0'. No. ;!='J-;V.- -Plant in the snn.

In all these observations it was uotii-ed that the l)asal leall.'ts, hence tho.se nearest
the percussion, responded lirst aiul most strongly; also, that the ellect of percussion did
not appear until lift ecu or twenty seconds had elapsed, after which the motion became
an accelerating one until tlie maximum of change was reached ; the time for recuperation,
as indicated above, thus embraces both depn>ssion and subsequent elevation to normal
imsition. In all these cases one fact is conspicuous, viz., the relation of recuperation to
direct action of the sunlight. Wlienever the plant was in the sun the leaves were much
less depressed from percussion, and their recuperation was much more rapid as .ompared
with leaves 'n the shade.

Nyctituopism.— The nyctitropic. or true sleep movement, is tliat which essentially
characterizes the leav.'s of Kobinia. Tlu'y may also manifest during th.> day, uiuler the
inlluen.v of bri-ht sunshine, a paraheliotropic movement, during whi.h the general
tendency is for the edges to be turned upward to the sun, as if to i'heck its inlluence. As
Darwin has already pointed out, ' the object of this movement is totally ditierent from
that of sh.ep movement, and is doubtless designed to lessen the destructive mlluence of
too intense sunlight upon the chlorophyll. _

■ iiisi

' Movements of Plants, 355, 445.

i^l^

80

i'i:nii.\t,t.i>w on MKCIIAMSM

iif/ r

Our i>l)S('i\ iiiioiis liMVi' bi'cii ;lllll(>^t wliolly •■miliiicd to the tnii- uyililnipir inovciiirnt.
till' piimipal (lata i>r \vhi<li wr lia\f colliTiid in ((Hini'rtinii with M. ('hapiiiaii and ( 1. Iv

l"<)ol('\ .

t^lt'op-imni'incnl usually ln'iiins within hali'aii hour ai'lcr suiiHct. thoiiuh lliis period
appears to hrioiiie loii'jer as the si'asnii iidvaiiees. In nil eases, it has l)een most
(onspieuoii^ that ieavi's al an elexatiuii. e i;'. tho>e on the to[)s of trees, assume lhe
sleep pusiiion niu«h sooni'r than those ;it a luwer level. No y-eneral rate o| ehnn-^i'.
however, (an lie staled lor all the leaves, siine it is innnd that the lenllets Tail into the
iioeturnal position at verv irreiiiilar intervals, some assuminti' tlsis position very earlv in
the eveiiiiii;'. while oth-'Vs remain in their diurnal jiosition until tpiite late. The sleep-
movement is u'enerallv eom])leled hy lii.;i(i p ni. l-rom that time on tliere is no iliauiie
in position, until the aetual awakening neeurs. wiiieli l)eiiins just helore dawn. With
rt'lereiiee to this, the ioUowiiiL;' extraet Iroin our notes will L;ive the t;eiieral leatures of
tlie ehauLre : —

"At 2 o'eloek a.m. the maximum darkness and minimum temperature have just
l)assed, aiul the older leavi's show the lirst siiiiis ol' avakeninu'. many of the leallets l)eini:-
expanded .">' or I't from iheir lormer sl.'i>p position. At -l.'.W the leallets have opened to
to an aiiLile of l.'i .and at 4 o'eloek tiny are well exi>aiuled. the most marked ehanL;v
oeeiirrini: within the latter hour from an examination of the aeeonjpanyins^ table the
<j:eneral « onditions ihroULihout the niiiht may he obtained. The temperature was taken
irom an exposed thermometer, huuu' at the height of, and amon<i', thi' plants observed.
This will aeeount for the variations of temperature noted in one or two instances : —

rir

te

llnll

7.:;n

1 111.

S.eii

'.

8.:'.(i

'•

'.i.eii

<i

11. .".11

"

1(1.1111

ti

lo.;'it>

"

li.(«i

"

11 :;o

ti

I'J.IHI

"

lL'.:;o

ji.ni

l.(»tl

l.;'.e

(t

U' IK 1

■'

•.'.:;u

■•

r>.iiii

"

;i.:;ii

(•

l.:;n

•'

■fr.Mi'.

Ki M m:ks.

li;.00''('. r,»'a\('S(li'sin;.'.
lii.'dl .Sl<v clear all iiiv.'lit.

lli.L'.'.

\h:s>

iri.riO

llKKI

Id.-.'.-.

I.i^:t\cs ;il

[ flosctl.

I't.fMI

I4.:;(i

II.:;.-.

11. I'll

M;l^. (lar

vllfS.S.

1L'.7.-.

i-t^avfs li(

_'ill to 0|K'll

i:;.(iii

i:;..')0

'•••-"■"

1 ;;.'.',-)

I/«aven al

(l|K'll.

'J he loadiiuf features of the awakening- are, that tTie process begins al or immediately
following the periods of maxitnum (hirkne.ss and ininimuni teniporaturo, and that it is
completed before the sun rises above the horizon. As in going to sleep, the lirst change is

!<:» I

OK MOVK.MI-INTS IN I'LANTS. 81

iiot.'d in those hmvos which are hi^lK-st. so in the iiwakiMiin-.' the Mime liirt is .onspienons.
Important as lliese i'a<ts aiv to tlic irenerai (piestion of iiy.titvopie niovenienl, we ran
only intmhi.e them imid..ntally at this time, since it is not (mr pnwiit purpose to
determine tiie precise inilueiire of external < auses upon the processes ol' n'r,,\vth whereby
these chanti-es are eliected. hut simply to dei -nine the mechanism ol' movement throu<,'h
tlie various tissues involved, ^\ Care, thcrdnrc. more intimately concerned in coMsidering
the various chanues \vhi« h occur in tlie leal' and leallet durin!4- the process ol'sleepim^' and
wakiny.

As the ])eriod ol' sleep approaches, the most conspicuous indication is to he i'ound in
the change ol' position which the leallets assume. From a horizontal or slightly elevated
position, they •••radually droop, until they assume a position at rii^ht aiurles to tiieir
normal diurnal i)osition ; thus, assuminii' the leal" as a whole to he horizontal, eaih leaflet
heconu's vertical. Tw(» imiiortaiit facts are here to he noted, viz., the relation of these
I'liaiiges to ijravitution, ami the indications they i^'ive of the operatiiin of an active force.
Whatever the position of the leaf as a whole may he, the leallets are i'ouiul to he
inllueiiced in certain directions hy the action of n'ravitatioii upon their mass. Thus, if the
leaf as a whole he horizontal, the droopinti' leallets will linally assume a position perpen-
dicular to its leimth. If it lie raised or depressed above or below the horizontal, the leaf-
lets no longer hang i)erpendicular to the leaf — with reference to its length — but fall
vertically. Thus each leallet is seen to turn laterally upon its peliolule as an axis, in
direct response to the inllnence of gravitation upon its mass, and in this respect it is inde-
jH'ndent of the position of the leaf as a whoh'. In harmony with this, it will always be
found that, in petiolules of a depressed leaf, there is a distinct torsion <onforming to the
relation which ihe leallet bears to its main rachis. In leaves which hang almost vertically
from drooping limbs, the leallets thus often come to lie nearly parallel with the rachis.

When the leaflets fall into the sleep position, there is always a stronu' tendency for
them to pass by the vertical plane passing longitudinally throueh the leaf; or in other
words, the movemejit of the leaflets, witli respect to the width of the leaf, is independent of
gravitation. As the-sleep movement progresses, the leallets of each pair hang c|uite parallel,
being .separated throughout by a distance of •') or S mm., representing the combined
width of the rachis and length of the two iH'tiolules. Soon, however, each leallet bends
in at the tij) toward the other, so that they linally touch. This is eliected in part by
a curvature throughout the entire length of each lealh't, but much more by a continued
curvature of the pulvinus of the petiolule, the result being that each tip is carried .several
millimetres beyond that point which would be determined by tiravitation alone. IJemov-
ing the opposite leallet of each pair, does not seem to affect the movement of that remain-
ing. In the terminal leallet, the sleep position is assumed precisely as if it were a lateral
leallet, with the difference that its chaniiv of position is much greater, and it is carried
much farther past the vertical. Without any regard to the position of the leaf as a whole,
the lermiiutl leaflet drops until it forms an acute angle with the rachis on its lower side.
If the leaf be horizontal, the terminal h'afict bi-nds .several degrees past the vertical. If,
however, the leaf be drooping, then the leaflet still establishes the same relation to the
rachis, and thus oft(>u becomes horizontal or even turns up past the horizontal. In the case
of leaves which were hanging vrtically, this rellex position of the terminal leallet was
often found to be 10 above th»" horizontal, or about 100 from the position which would

Sec. IV., IhSG. 11.

lis

i 1'^^

I i

i
I! %

i i;

n

82

I'KNIIAf.l.oW ON Mi:('IIAMSM

1)1' cstiililislicd l>y i:ni\ il;iiinii mIoih- TIh'>'' I'm' Is. tlu'rcron', slmw lliat iln' true sliM-p nmvc
ui'-ni is iiol p;issivi', siiuihirly in thai ini'viou^ly iUmiiss d, Imt that it is (Iiic to an artivi

lur.c. til

<• iiii'asiiri' 111 wlii 'li is partly i'\pii'>M'(

1 ill I hi' (h'Li'rcr (o whii'h it ovcrrnim

trravitatidii.

Ill iissuniiim' thf sleep pn>iii(Mi, cai h Ira (let dinops : hist, l>y curvaliin' ol' the pi'liolule
ihrduijh itswlidlc leiiLiih: se. mnlK . l>y ii sharper h-iitliiiu,' ill (he jmiet ion o| petioliile and

illei ; ihinllv. 1

t\ a slu

III iiiivature ihroiliih llie entire leimtli oi' llielcaHet itstdl'. in

tl

lis iDinieiiioii It i> iiiiporiiiiit In iiiite thai, when jeallels are removed by I'Ullinu' away
at tlio I'xtri'iiie hase ol ihe |iet inlnles, the lalter almost imniediatoly eiirvf, the curvature
conl'ormiiii;" to that wliieji is piodueed during the normal slceji movement. Then.' is, in
all this, a stroni>- indication that the diann'e is due to r»dease of tension in the tissue oi'the
l)ulviiius.

In the leaf a^ a whole, tliei'e is ( oiiiparati\ ely little movement. Darwin' has shown
that there may he an ai tiial elcvalinii duriiiL;' sleep, to the extent ol' ;{ or 4 . Our own
observations show, and i>r(il)alily with 'jrealer rreijueiny, a depression oi'the whole leal' to
tiio extent of •'!.") or Vi . The saiiii' i haiiee may sometimes he induced liy irritation,
occasional!} in a more marked (h'iiree in all .^uch chanii'es ol" ]H)s:'tion. they appear to l>e
aciomplished at I he ext ii'iiie liase of ihe pulviim> which thus a<'ts as a hinL;e. As the leal
drops, the central rid^ie on the lower side of the pulvinus recedes slightly, the ciisliion
aroiuid it becomes somewhat wrinkled, Imt mi the upper suh' the i)ulvinu.s is drawn
quite tense and smooth. It i^ imixirtaiit her.', to note the ditl'erciice ln'tween the pulvinus
of the li'af and of tin' leallet durinii the sleep movement, as it will l)e found to Im'

correhited iii a most .vmnilicaiit manner, to the inieriial structure m eacli caso

C('l.\CM'Sl(i\.

The dedui tioiis which c an reasonal)ly lie iiased upon the foren'oiiiL;' facts, may bo brielly
stated.

V>y comparison with Cuiiirbita and Vitis. thi' absence (d'any marked sensitiveness in
Rol»ini.i, Would imi)ly the allien, 'e of a tissue iu whicli variation of tension under external
irritation is a special fund ion. 'I'his we iind (juile in accord with the presence ol
colloiichyma in the former, its aliseiice in the hitler, and the ridation whicli it bears to the
sensitiveness of the oriian itscdl'. \Vhate\,.r t laiismis.vioii of impulse there may be, can be
readily determined as in tlu' previous c.ises ihroimh the continuity of i)rotoplasm.

In the h'af, the .soft lissue of tlie j)iih inns proi)er is that in which the variations of
tension under external inllueiices is determined. ^Moreover, the fact that this tissue is
fi'realer lielow than aljove the centre, points to its serviim- as t\u' true orectilo tissue
wherefer its internal tension is auLiiinnied suJlici.Mitly — liecomini^ simply passive when its
tension is ivdaced Ijelow a certain jxtint. This is a more important lactor in the pulvinus
ol the leaflet than in tlie lar^e pulvinus, since the chaimes in the leallet are frrcater,
and require a relatively "Teater eroctile lone. As the i)ulviiius determines the upward
movement, the included librous tdonieuts duterniine tho downward aud rellex movements.

' Movoiiionts of riants, :;."..').

OF .\I(»\ KMKNTS IX rivANTS.

88

Hciiif? in II Mtiito ot'positivo tension, any vi-lfuso oi' tension in tlic snnoun(lin<y pnlvinus nt
once porniits contruction in tln' liii.st. UndiT irritation, imd pos.sil)ly other inliuinnt's, this

may also l)e inereased l»y h)ssol water, aso<enrs in a more niaiked decree in the foUeiieliynia
ol' Ciirurhita. The direction of l)endinL:', as (h'terniined hy this < oiitraetion, depends upon
t)u' distribution of the hast in the or^an. In the ease ollhe leallels, we have seen the bast
to be so disposed below the axisoi'lhe pet inlule, that the latt.'r ean only curve downward,
this beini>' i'aeilitated, moreover, by the vascular structure beinjjf open alon*; the upper side.
In the nuiin pnlvinus, the closed cylinder of vascular strueture preserves a condition of
rijjidity in all parts except at the extreme l)ase. where we lind the vascular stru< ture to
become Itranched in such a way as to produce a true joint in cuune. tion with an intercel-
lular cavity.

KXI'I.ANATION dl' I'r.ATKS,
I'l.ATi; III.

Vijrnre, lialf iiiitiiral Hi/.o, sliewinj,' iiii.voiiiont ..I' tiMnlril li|i. Tlic li-uw is .seen us il'tlic! (>1>s(mvit wi'i'c at
at llio liiiscnftlii' tciiili'il IniiUiiin leuunl the tip.

I'l.ATI! IV.

t'i^;. 1.— Ilalt'.scrtinn (■!' Ii'ii'liil avut t:\' i'limrhild jljid dii.
((() Vilir(ij.'('ii.
(Ii) Ciillt'iuliyMia.
(<•) .\(tivt! inu'i'iicliynia.
(</) I'.ast.

((') Viis(iil:ir liimdlt's.
(/) ('(■ntral pith paiciii'liyiiiii.
" L'.— I5a.st cells ^ L'i;ii.

A. Pariajr activi' pciiiul.
I'l. .M'tiT coilini: (it tcMcliil.
" ;!. — ('iillout'liynia x litiO.
'I 4.— Contiiuiity 111' I'rotepla.siii in (■ellciicliyiua x 'Jdil.

" ,"). — VilTni'di .X l:

ri.ATi: V.

Vij,. 1.— Half cni.^s-si'clien el'tciuliil el' Valx vunl'ijuliit, Michx.,
d- coUeiu'livnui.

ic. iiurcncliyii

"■. \Miik1.

;.. pith.

vil)r(ii.'oii (i.ssUK X 'Jiiti,

;>. — (■/. c'oliciicliyiMa
■1, — woikI tissue

L'dli,

A. Unrintr activity (il'tlio lend
r.. After ct'r-sation nf motieii.

.r,._('r,,ss sei'tieii el'siiiallov pn

va.s('alar structurt' te lla; iiulviiais li.-suo.
(l.—i-tracturo of vascular zone x 26(1.

A. r.cfero iiyctitnipic activity.

11. Duriu;,' nyctitropic activity-

IvilUlS nf Icallct, yiV''/'"''! pxnilhirilflil X

(Iti, sluAvini.' relatien of ecntnil

m

IV'-M

m