,picture3 ,book cover ,,the ,,movements ,,and ,,habits ,,of ,,climbing ,,plants4 ,,by ,,charles ,,darwin1 ,f4,r4,s4 99 99 99 99 99 ,,popular ,,edition 99 99 99 99 99 ,,london3 ,,john ,,murray1 ,,albemarle ,,street4 #aijf4 ,,preface ,,this ,essay first appeared in the ninth volume of the #8,journal of the ,linnean ,society1' published in #ahfe4 ,it is here reproduced in a corrected and1 ,i hope1 clearer form1 with some additional facts4 ,the illustrations were drawn by my son1 ,george ,darwin4 ,fritz ,mller1 after the publication of my paper1 sent to the ,linnean ,society 7,journal1 vol4 ix41 p4 #cdd7 some interesting observations on the climbing plants of ,south ,brazil1 to which ,i shall frequently refer4 ,recently two important memoirs1 chiefly on the difference in growth between the upper and lower sides of tendrils1 and on the mechanism of the movements of twining-plants1 by ,dr4 ,hugo de ,vries1 have appeared in the #8,arbeiten des ,botanischen ,instituts in ,wrzburg1' ,heft4 iii41 #ahgc4 ,these memoirs ought to be carefully studied by every one interested in the subject1 as ,i can here give only references to the more important points4 ,this excellent observer1 as well as ,professor ,sachs1 iv attributes all the movements of tendrils to rapid growth along one side2 but1 from reasons assigned towards the close of my fourth chapter1 ,i cannot persuade myself that this holds good with respect to those due to a touch4 ,in order that the reader may know what points have interested me most1 ,i may call his attention to certain tendril-bearing plants2 for instance1 ,bignonia capreolata1 ,coba1 ,echinocystis1 and ,hanburya1 which display as beautiful adaptations as can be found in any part of the kingdom of nature4 ,it is1 also1 an interesting fact that intermediate states between organs fitted for widely different functions1 may be observed on the same individual plant of ,corydalis claviculata and the common vine2 and these cases illustrate in a striking manner the principle of the gradual evolution of species4 ,,appendix ,,to ,,preface 7#ahhb74 ,,since the publication of this ,edition two papers by eminent botanists have appeared2 ,schwendener1 #8,das ,winden der ,pflanzen' 7,monatsberichte der ,berliner ,akademie1 ,dec4 #ahha71 and ,j4 ,sachs1 #8,notiz ber ,schlingpflanzen' 7,arbeiten des botanischen ,instituts in ,wrzburg1 ,bd4 ii4 p4 #gai1 #ahhb74 ,the view 8that the capacity of revolving1 on which most climbers depend1 is inherent1 though undeveloped1 in almost every plant in the vegetable kingdom0 7#8,climbing ,plants1' p4 #bje71 has been confirmed by the observations on circumnutation since given in #8,the ,power of ,movement in ,plants4' ,,errata4 ,on pp4 #bh1 #cb1 #dj1 #ec1 statements are made with reference to the supposed acceleration of the revolving movement towards the light4 ,it appears from the observations given in #8,the ,power of ,movement in ,plants1' p4 #dea1 that these conclusions were drawn from insufficient observations1 and are erroneous4 ,,the ,,movements ,,and ,,habits ,,of ,,climbing ,,plants4 ,,chapter ,i4 ,,twining ,,plants4 ,introductory remarks--,description of the twining of the ,hop--,torsion of the stems--,nature of the revolving movement1 and manner of ascent--,stems not irritable--,rate of revolution in various plants--,thickness of the support round which plants can twine--,species which revolve in an anomalous manner4 ,i ,,was led to this subject by an interesting1 but short paper by ,professor ,asa ,gray on the movements of the tendrils of some ,cucurbitaceous plants4 #a;a ,my observations were more than half completed before ,i learnt that the surprising phenomenon of the spontaneous revolutions of the stems and tendrils of climbing plants had been long ago observed by ,palm and by ,hugo von ,mohl1 #a;b and had subsequently been the subject of two memoirs by ,dutrochet4 #a;c ,nevertheless1 ,i believe that my observations1 founded on the examination of above a hundred widely distinct living species1 contain sufficient novelty to justify me in publishing them4 ,climbing plants may be divided into four classes4 ,first1 those which twine spirally round a support1 and are not aided by any other movement4 ,secondly1 those endowed with irritable organs1 which when they touch any object clasp it2 such organs consisting of modified leaves1 branches1 or flower-peduncles4 ,but these two classes sometimes graduate to a certain extent into one another4 ,plants of the third class ascend merely by the aid of hooks2 and those of the fourth by rootlets2 but as in neither class do the plants exhibit any special movements1 they present little interest1 and generally when ,i speak of climbing plants ,i refer to the two first great classes4 ,,twining ,,plants4 ,this is the largest subdivision1 and is apparently the primordial and simplest condition of the class4 ,my observations will be best given by taking a few special cases4 ,when the shoot of a ,hop 7,humulus lupulus7 rises from the ground1 the two or three first-formed joints or internodes are straight and remain stationary2 but the next-formed1 whilst very young1 may be seen to bend to one side and to travel slowly round towards all points of the compass1 moving1 like the hands of a watch1 with the sun4 ,the movement very soon acquires its full ordinary velocity4 ,from seven observations made during ,august on shoots proceeding from a plant which had been cut down1 and on another plant during ,april1 the average rate during hot weather and during the day is #b hrs4 #h m4 for each revolution2 and none of the revolutions varied much from this rate4 ,the revolving movement continues as long as the plant continues to grow2 but each separate internode1 as it becomes old1 ceases to move4 ,to ascertain more precisely what amount of movement each internode underwent1 ,i kept a potted plant1 during the night and day1 in a well-warmed room to which ,i was confined by illness4 ,a long shoot projected beyond the upper end of the supporting stick1 and was steadily revolving4 ,i then took a longer stick and tied up the shoot1 so that only a very young internode1 #a of an inch in length1 was left free4 ,this was so nearly upright that its revolution could not be easily observed2 but it certainly moved1 and the side of the internode which was at one time convex became concave1 which1 as we shall hereafter see1 is a sure sign of the revolving movement4 ,i will assume that it made at least one revolution during the first twenty-four hours4 ,early the next morning its position was marked1 and it made a second revolution in #i hrs42 during the latter part of this revolution it moved much quicker1 and the third circle was performed in the evening in a little over #c hrs4 ,as on the succeeding morning ,i found that the shoot revolved in #b hrs4 #de m41 it must have made during the night four revolutions1 each at the average rate of a little over #c hrs4 ,i should add that the temperature of the room varied only a little4 ,the shoot had now grown #c inches in length1 and carried at its extremity a young internode #a inch in length1 which showed slight changes in its curvature4 ,the next or ninth revolution was effected in #b hrs4 #cj m4 ,from this time forward1 the revolutions were easily observed4 ,the thirty-sixth revolution was performed at the usual rate2 so was the last or thirty-seventh1 but it was not completed2 for the internode suddenly became upright1 and after moving to the centre1 remained motionless4 ,i tied a weight to its upper end1 so as to bow it slightly and thus detect any movement2 but there was none4 ,some time before the last revolution was half performed1 the lower part of the internode ceased to move4 ,a few more remarks will complete all that need be said about this internode4 ,it moved during five days2 but the more rapid movements1 after the performance of the third revolution1 lasted during three days and twenty hours4 ,the regular revolutions1 from the ninth to thirty-sixth inclusive1 were effected at the average rate of #b hrs4 #ca m42 but the weather was cold1 and this affected the temperature of the room1 especially during the night1 and consequently retarded the rate of movement a little4 ,there was only one irregular movement1 which consisted in the stem rapidly making1 after an unusually slow revolution1 only the segment of a circle4 ,after the seventeenth revolution the internode had grown from #a to #f inches in length1 and carried an internode #a inch long1 which was just perceptibly moving2 and this carried a very minute ultimate internode4 ,after the twenty-first revolution1 the penultimate internode was #b inches long1 and probably revolved in a period of about three hours4 ,at the twenty-seventh revolution the lower and still moving internode was #h1 the penultimate #c1 and the ultimate #b inches in length2 and the inclination of the whole shoot was such1 that a circle #ai inches in diameter was swept by it4 ,when the movement ceased1 the lower internode was #i inches1 and the penultimate #f inches in length2 so that1 from the twenty-seventh to thirty-seventh revolutions inclusive1 three internodes were at the same time revolving4 ,the lower internode1 when it ceased revolving1 became upright and rigid2 but as the whole shoot was left to grow unsupported1 it became after a time bent into a nearly horizontal position1 the uppermost and growing internodes still revolving at the extremity1 but of course no longer round the old central point of the supporting stick4 ,from the changed position of the centre of gravity of the extremity1 as it revolved1 a slight and slow swaying movement was given to the long horizontally projecting shoot2 and this movement ,i at first thought was a spontaneous one4 ,as the shoot grew1 it hung down more and more1 whilst the growing and revolving extremity turned itself up more and more4 ,with the ,hop we have seen that three internodes were at the same time revolving2 and this was the case with most of the plants observed by me4 ,with all1 if in full health1 two internodes revolved2 so that by the time the lower one ceased to revolve1 the one above was in full action1 with a terminal internode just commencing to move4 ,with ,hoya carnosa1 on the other hand1 a depending shoot1 without any developed leaves1 #cb inches in length1 and consisting of seven internodes 7a minute terminal one1 an inch in length1 being counted71 continually1 but slowly1 swayed from side to side in a semicircular course1 with the extreme internodes making complete revolutions4 ,this swaying movement was certainly due to the movement of the lower internodes1 which1 however1 had not force sufficient to swing the whole shoot round the central supporting stick4 ,the case of another ,asclepiadaceous plant1 viz41 ,ceropegia ,gardnerii1 is worth briefly giving4 ,i allowed the top to grow out almost horizontally to the length of #ca inches2 this now consisted of three long internodes1 terminated by two short ones4 ,the whole revolved in a course opposed to the sun 7the reverse of that of the ,hop71 at rates between #e hrs4 #ae m4 and #f hrs4 #de m4 for each revolution4 ,the extreme tip thus made a circle of above #e feet 7or #fb inches7 in diameter and #af feet in circumference1 travelling at the rate of #cb or #cc inches per hour4 ,the weather being hot1 the plant was allowed to stand on my study-table2 and it was an interesting spectacle to watch the long shoot sweeping this grand circle1 night and day1 in search of some object round which to twine4 ,if we take hold of a growing sapling1 we can of course bend it to all sides in succession1 so as to make the tip describe a circle1 like that performed by the summit of a spontaneously revolving plant4 ,by this movement the sapling is not in the least twisted round its own axis4 ,i mention this because if a black point be painted on the bark1 on the side which is uppermost when the sapling is bent towards the holder's body1 as the circle is described1 the black point gradually turns round and sinks to the lower side1 and comes up again when the circle is completed2 and this gives the false appearance of twisting1 which1 in the case of spontaneously revolving plants1 deceived me for a time4 ,the appearance is the more deceitful because the axes of nearly all twining-plants are really twisted2 and they are twisted in the same direction with the spontaneous revolving movement4 ,to give an instance1 the internode of the ,hop of which the history has been recorded1 was at first1 as could be seen by the ridges on its surface1 not in the least twisted2 but when1 after the #cgth revolution1 it had grown #i inches long1 and its revolving movement had ceased1 it had become twisted three times round its own axis1 in the line of the course of the sun2 on the other hand1 the common ,convolvulus1 which revolves in an opposite course to the ,hop1 becomes twisted in an opposite direction4 ,hence it is not surprising that ,hugo von ,mohl 7p4 #aje1 #ajh1 c47 thought that the twisting of the axis caused the revolving movement2 but it is not possible that the twisting of the axis of the ,hop three times should have caused thirty-seven revolutions4 ,moreover1 the revolving movement commenced in the young internode before any twisting of its axis could be detected4 ,the internodes of a young ,siphomeris and ,lecontea revolved during several days1 but became twisted only once round their own axes4 ,the best evidence1 however1 that the twisting does not cause the revolving movement is afforded by many leaf-climbing and tendril-bearing plants 7as ,pisum sativum1 ,echinocystis lobata1 ,bignonia capreolata1 ,eccremocarpus scaber1 and with the leaf-climbers1 ,solanum jasminoides and various species of ,clematis71 of which the internodes are not twisted1 but which1 as we shall hereafter see1 regularly perform revolving movements like those of true twining-plants4 ,moreover1 according to ,palm 7pp4 #cj1 #ie7 and ,mohl 7p4 #adi71 and ,lon1 #h internodes may occasionally1 and even not very rarely1 be found which are twisted in an opposite direction to the other internodes on the same plant1 and to the course of their revolutions2 and this1 according to ,lon 7p4 #cef71 is the case with all the internodes of a certain variety of ,phaseolus multiflorus4 ,internodes which have become twisted round their own axes1 if they have not ceased to revolve1 are still capable of twining round a support1 as ,i have several times observed4 ,mohl has remarked 7p4 #aaa7 that when a stem twines round a smooth cylindrical stick1 it does not become twisted4 #i;a ,accordingly ,i allowed kidney-beans to run up stretched string1 and up smooth rods of iron and glass1 one-third of an inch in diameter1 and they became twisted only in that degree which follows as a mechanical necessity from the spiral winding4 ,the stems1 on the other hand1 which had ascended ordinary rough sticks were all more or less and generally much twisted4 ,the influence of the roughness of the support in causing axial twisting was well seen in the stems which had twined up the glass rods2 for these rods were fixed into split sticks below1 and were secured above to cross sticks1 and the stems in passing these places became much twisted4 ,as soon as the stems which had ascended the iron rods reached the summit and became free1 they also became twisted2 and this apparently occurred more quickly during windy than during calm weather4 ,several other facts could be given1 showing that the axial twisting stands in some relation to inequalities in the support1 and likewise to the shoot revolving freely without any support4 ,many plants1 which are not twiners1 become in some degree twisted round their own axes2 #i;b but this occurs so much more generally and strongly with twining-plants than with other plants1 that there must be some connexion between the capacity for twining and axial twisting4 ,the stem probably gains rigidity by being twisted 7on the same principle that a much twisted rope is stiffer than a slackly twisted one71 and is thus indirectly benefited so as to be enabled to pass over inequalities in its spiral ascent1 and to carry its own weight when allowed to revolve freely4 #aj ,i have alluded to the twisting which necessarily follows on mechanical principles from the spiral ascent of a stem1 namely1 one twist for each spire completed4 ,this was well shown by painting straight lines on living stems1 and then allowing them to twine2 but1 as ,i shall have to recur to this subject under ,tendrils1 it may be here passed over4 ,the revolving movement of a twining plant has been compared with that of the tip of a sapling1 moved round and round by the hand held some way down the stem2 but there is one important difference4 ,the upper part of the sapling when thus moved remains straight2 but with twining plants every part of the revolving shoot has its own separate and independent movement4 ,this is easily proved2 for when the lower half or two-thirds of a long revolving shoot is tied to a stick1 the upper free part continues steadily revolving4 ,even if the whole shoot1 except an inch or two of the extremity1 be tied up1 this part1 as ,i have seen in the case of the ,hop1 ,ceropegia1 ,convolvulus1 c41 goes on revolving1 but much more slowly2 for the internodes1 until they have grown to some little length1 always move slowly4 ,if we look to the one1 two1 or several internodes of a revolving shoot1 they will be all seen to be more or less bowed1 either during the whole or during a large part of each revolution4 ,now if a coloured streak be painted 7this was done with a large number of twining plants7 along1 we will say1 the convex surface1 the streak will after a time 7depending on the rate of revolution7 be found to be running laterally along one side of the bow1 then along the concave side1 then laterally on the opposite side1 and1 lastly1 again on the originally convex surface4 ,this clearly proves that during the revolving movement the internodes become bowed in every direction4 ,the movement is1 in fact1 a continuous self-bowing of the whole shoot1 successively directed to all points of the compass2 and has been well designated by ,sachs as a revolving nutation4 ,as this movement is rather difficult to understand1 it will be well to give an illustration4 ,take a sapling and bend it to the south1 and paint a black line on the convex surface2 let the sapling spring up and bend it to the east1 and the black line will be seen to run along the lateral face fronting the north2 bend it to the north1 the black line will be on the concave surface2 bend it to the west1 the line will again be on the lateral face2 and when again bent to the south1 the line will be on the original convex surface4 ,now1 instead of bending the sapling1 let us suppose that the cells along its northern surface from the base to the tip were to grow much more rapidly than on the three other sides1 the whole shoot would then necessarily be bowed to the south2 and let the longitudinal growing surface creep round the shoot1 deserting by slow degrees the northern side and encroaching on the western side1 and so round by the south1 by the east1 again to the north4 ,in this case the shoot would remain always bowed with the painted line appearing on the several above specified surfaces1 and with the point of the shoot successively directed to each point of the compass4 ,in fact1 we should have the exact kind of movement performed by the revolving shoots of twining plants4 #ab ,it must not be supposed that the revolving movement is as regular as that given in the above illustration2 in very many cases the tip describes an ellipse1 even a very narrow ellipse4 ,to recur once again to our illustration1 if we suppose only the northern and southern surfaces of the sapling alternately to grow rapidly1 the summit would describe a simple arc2 if the growth first travelled a very little to the western face1 and during the return a very little to the eastern face1 a narrow ellipse would be described2 and the sapling would be straight as it passed to and fro through the intermediate space2 and a complete straightening of the shoot may often be observed in revolving plants4 ,the movement is frequently such that three of the sides of the shoot seem to be growing in due order more rapidly than the remaining side2 so that a semi-circle instead of a circle is described1 the shoot becoming straight and upright during half of its course4 ,when a revolving shoot consists of several internodes1 the lower ones bend together at the same rate1 but one or two of the terminal ones bend at a slower rate2 hence1 though at times all the internodes are in the same direction1 at other times the shoot is rendered slightly serpentine4 ,the rate of revolution of the whole shoot1 if judged by the movement of the extreme tip1 is thus at times accelerated or retarded4 ,one other point must be noticed4 ,authors have observed that the end of the shoot in many twining plants is completely hooked2 this is very general1 for instance1 with the ,asclepiadace4 ,the hooked tip1 in all the cases observed by me1 viz4 in ,ceropegia1 ,sphrostemma1 ,clerodendron1 ,wistaria1 ,stephania1 ,akebia1 and ,siphomeris1 has exactly the same kind of movement as the other internodes2 for a line painted on the convex surface first becomes lateral and then concave2 but1 owing to the youth of these terminal internodes1 the reversal of the hook is a slower process than that of the revolving movement4 #ad ,this strongly marked tendency in the young1 terminal and flexible internodes1 to bend in a greater degree or more abruptly than the other internodes1 is of service to the plant2 for not only does the hook thus formed sometimes serve to catch a support1 but 7and this seems to be much more important7 it causes the extremity of the shoot to embrace the support much more closely than it could otherwise have done1 and thus aids in preventing the stem from being blown away during windy weather1 as ,i have many times observed4 ,in ,lonicera brachypoda the hook only straightens itself periodically1 and never becomes reversed4 ,i will not assert that the tips of all twining plants when hooked1 either reverse themselves or become periodically straight1 in the manner just described2 for the hooked form may in some cases be permanent1 and be due to the manner of growth of the species1 as with the tips of the shoots of the common vine1 and more plainly with those of ,cissus discolor--plants which are not spiral twiners4 ,the first purpose of the spontaneous revolving movement1 or1 more strictly speaking1 of the continuous bowing movement directed successively to all points of the compass1 is1 as ,mohl has remarked1 to favour the shoot finding a support4 ,this is admirably effected by the revolutions carried on night and day1 a wider and wider circle being swept as the shoot increases in length4 ,this movement likewise explains how the plants twine2 for when a revolving shoot meets with a support1 its motion is necessarily arrested at the point of contact1 but the free projecting part goes on revolving4 ,as this continues1 higher and higher points are brought into contact with the support and are arrested2 and so onwards to the extremity2 and thus the shoot winds round its support4 ,when the shoot follows the sun in its revolving course1 it winds round the support from right to left1 the support being supposed to stand in front of the beholder2 when the shoot revolves in an opposite direction1 the line of winding is reversed4 ,as each internode loses from age its power of revolving1 it likewise loses its power of spirally twining4 ,if a man swings a rope round his head1 and the end hits a stick1 it will coil round the stick according to the direction of the swinging movement2 so it is with a twining plant1 a line of growth travelling round the free part of the shoot causing it to bend towards the opposite side1 and this replaces the momentum of the free end of the rope4 ,all the authors1 except ,palm and ,mohl1 who have discussed the spiral twining of plants1 maintain that such plants have a natural tendency to grow spirally4 ,mohl believes 7p4 #aab7 that twining stems have a dull kind of irritability1 so that they bend towards any object which they touch2 but this is denied by ,palm4 ,even before reading ,mohl's interesting treatise1 this view seemed to me so probable that ,i tested it in every way that ,i could1 but always with a negative result4 ,i rubbed many shoots much harder than is necessary to excite movement in any tendril or in the foot-stalk of any leaf climber1 but without any effect4 ,i then tied a light forked twig to a shoot of a ,hop1 a ,ceropegia1 ,sphrostemma1 and ,adhatoda1 so that the fork pressed on one side alone of the shoot and revolved with it2 ,i purposely selected some very slow revolvers1 as it seemed most likely that these would profit most from possessing irritability2 but in no case was any effect produced4 #af ,moreover1 when a shoot winds round a support1 the winding movement is always slower1 as we shall immediately see1 than whilst it revolves freely and touches nothing4 ,hence ,i conclude that twining stems are not irritable2 and indeed it is not probable that they should be so1 as nature always economizes her means1 and irritability would have been superfluous4 ,nevertheless ,i do not wish to assert that they are never irritable2 for the growing axis of the leaf-climbing1 but not spirally twining1 ,lophospermum scandens is1 certainly irritable2 but this case gives me confidence that ordinary twiners do not possess any such quality1 for directly after putting a stick to the ,lophopermum1 ,i saw that it behaved differently from a true twiner or any other leaf-climber4 #ag ,the belief that twiners have a natural tendency to grow spirally1 probably arose from their assuming a spiral form when wound round a support1 and from the extremity1 even whilst remaining free1 sometimes assuming this form4 ,the free internodes of vigorously growing plants1 when they cease to revolve1 become straight1 and show no tendency to be spiral2 but when a shoot has nearly ceased to grow1 or when the plant is unhealthy1 the extremity does occasionally become spiral4 ,i have seen this in a remarkable manner with the ends of the shoots of the ,stauntonia and of the allied ,akebia1 which became wound up into a close spire1 just like a tendril2 and this was apt to occur after some small1 ill-formed leaves had perished4 ,the explanation1 ,i believe1 is1 that in such cases the lower parts of the terminal internodes very gradually and successively lose their power of movement1 whilst the portions just above move onwards and in their turn become motionless2 and this ends in forming an irregular spire4 ,when a revolving shoot strikes a stick1 it winds round it rather more slowly than it revolves4 ,for instance1 a shoot of the ,ceropegia1 revolved in #f hrs41 but took #i hrs4 #cj m4 to make one complete spire round a stick2 ,aristolochia gigas revolved in about #e hrs41 but took #i hrs4 #ae m4 to complete its spire4 ,this1 ,i presume1 is due to the continued disturbance of the impelling force by the arrestment of the movement at successive points2 and we shall hereafter see that even shaking a plant retards the revolving movement4 ,the terminal internodes of a long1 much-inclined1 revolving shoot of the ,ceropegia1 after they had wound round a stick1 always slipped up it1 so as to render the spire more open than it was at first2 and this was probably in part due to the force which caused the revolutions1 being now almost freed from the constraint of gravity and allowed to act freely4 ,with the ,wistaria1 on the other hand1 a long horizontal shoot wound itself at first into a very close spire1 which remained unchanged2 but subsequently1 as the shoot twined spirally up its support1 it made a much more open spire4 ,with all the many plants which were allowed freely to ascend a support1 the terminal internodes made at first a close spire2 and this1 during windy weather1 served to keep the shoots in close contact with their support2 but as the penultimate internodes grew in length1 they pushed themselves up for a considerable space 7ascertained by coloured marks on the shoot and on the support7 round the stick1 and the spire became more open4 #ah ,it follows from this latter fact that the position occupied by each leaf with respect to the support depends on the growth of the internodes after they have become spirally wound round it4 ,i mention this on account of an observation by ,palm 7p4 #cd71 who states that the opposite leaves of the ,hop always stand in a row1 exactly over one another1 on the same side of the supporting stick1 whatever its thickness may be4 ,my sons visited a hop-field for me1 and reported that though they generally found the points of insertion of the leaves standing over each other for a space of two or three feet in height1 yet this never occurred up the whole length of the pole2 the points of insertion forming1 as might have been expected1 an irregular spire4 ,any irregularity in the pole entirely destroyed the regularity of position of the leaves4 ,from casual inspection1 it appeared to me that the opposite leaves of ,thunbergia alata were arranged in lines up the sticks round which they had twined2 accordingly1 ,i raised a dozen plants1 and gave them sticks of various thicknesses1 as well as string1 to twine round2 and in this case one alone out of the dozen had its leaves arranged in a perpendicular line3 ,i conclude1 therefore1 ,palm's statement is not quite accurate4 ,the leaves of different twining-plants are arranged on the stem 7before it has twined7 alternately1 or oppositely1 or in a spire4 ,in the latter case the line of insertion of the leaves and the course of the revolutions coincide4 ,this fact has been well shown by ,dutrochet1 #ai who found different individuals of ,solanum dulcamara twining in opposite directions1 and these had their leaves in each case spirally arranged in the same direction4 ,a dense whorl of many leaves would apparently be incommodious for a twining plant1 and some authors assert that none have their leaves thus arranged2 but a twining ,siphomeris has whorls of three leaves4 ,if a stick which has arrested a revolving shoot1 but has not as yet been encircled1 be suddenly taken away1 the shoot generally springs forward1 showing that it was pressing with some force against the stick4 ,after a shoot has wound round a stick1 if this be withdrawn1 it retains for a time its spiral form2 it then straightens itself1 and again commences to revolve4 ,the long1 much-inclined shoot of the ,ceropegia previously alluded to offered some curious peculiarities4 ,the lower and older internodes1 which continued to revolve1 were incapable1 on repeated trials1 of twining round a thin stick2 showing that1 although the power of movement was retained1 this was not sufficient to enable the plant to twine4 ,i then moved the stick to a greater distance1 so that it was struck by a point #b inches from the extremity of the penultimate internode2 and it was then neatly encircled by this part of the penultimate and by the ultimate internode4 ,after leaving the spirally wound shoot for eleven hours1 ,i quietly withdrew the stick1 and in the course of the day the curled portion straightened itself and recommenced revolving2 but the lower and not curled portion of the penultimate internode did not move1 a sort of hinge separating the moving and the motionless part of the same internode4 ,after a few days1 however1 ,i found that this lower part had likewise recovered its revolving power4 ,these several facts show that the power of movement is not immediately lost in the arrested portion of a revolving shoot2 and that after being temporarily lost it can be recovered4 ,when a shoot has remained for a considerable time round a support1 it permanently retains its spiral form even when the support is removed4 ,when a tall stick was placed so as to arrest the lower and rigid internodes of the ,ceropegia1 at the distance at first of #ae and then of #ba inches from the centre of revolution1 the straight shoot slowly and gradually slid up the stick1 so as to become more and more highly inclined1 but did not pass over the summit4 ,then1 after an interval sufficient to have allowed of a semi-revolution1 the shoot suddenly bounded from the stick and fell over to the opposite side or point of the compass1 and reassumed its previous slight inclination4 ,it now recommenced revolving in its usual course1 so that after a semi-revolution it again came into contact with the stick1 again slid up it1 and again bounded from it and fell over to the opposite side4 ,this movement of the shoot had a very odd appearance1 as if it were disgusted with its failure but was resolved to try again4 ,we shall1 ,i think1 understand this movement by considering the former illustration of the sapling1 in which the growing surface was supposed to creep round from the northern by the western to the southern face2 and thence back again by the eastern to the northern face1 successively bowing the sapling in all directions4 ,now with the ,ceropegia1 the stick being placed to the south of the shoot and in contact with it1 as soon as the circulatory growth reached the western surface1 no effect would be produced1 except that the shoot would be pressed firmly against the stick4 ,but as soon as growth on the southern surface began1 the shoot would be slowly dragged with a sliding movement up the stick2 and then1 as soon as the eastern growth commenced1 the shoot would be drawn from the stick1 and its weight coinciding with the effects of the changed surface of growth1 would cause it suddenly to fall to the opposite side1 reassuming its previous slight inclination2 and the ordinary revolving movement would then go on as before4 ,i have described this curious case with some care1 because it first led me to understand the order in which1 as ,i then thought1 the surfaces contracted2 but in which1 as we now know from ,sachs and ,,ii4 de ,vries1 they grow for a time rapidly1 thus causing the shoot to bow towards the opposite side4 ,the view just given further explains1 as ,i believe1 a fact observed by ,mohl 7p4 #ace71 namely1 that a revolving shoot1 though it will twine round an object as thin as a thread1 cannot do so round a thick support4 ,i placed some long revolving shoots of a ,wistaria close to a post between #e and #f inches in diameter1 but1 though aided by me in many ways1 they could not wind round it4 ,this apparently was due to the flexure of the shoot1 whilst winding round an object so gently curved as this post1 not being sufficient to hold the shoot to its place when the growing surface crept round to the opposite surface of the shoot2 so that it was withdrawn at each revolution from its support4 ,when a free shoot has grown far beyond its support1 it sinks downwards from its weight1 as already explained in the case of the ,hop1 with the revolving extremity turned upwards4 ,if the support be not lofty1 the shoot falls to the ground1 and resting there1 the extremity rises up4 ,sometimes several shoots1 when flexible1 twine together into a cable1 and thus support one another4 ,single thin depending shoots1 such as those of the ,sollya ,drummondii1 will turn abruptly backwards and wind up on themselves4 ,the greater number of the depending shoots1 however1 of one twining plant1 the ,hibbertia dentata1 showed but little tendency to turn upwards4 ,in other cases1 as with the ,cryptostegia grandiflora1 several internodes which were at first flexible and revolved1 if they did not succeed in twining round a support1 become quite rigid1 and supporting themselves upright1 carried on their summits the younger revolving internodes4 ,here will be a convenient place to give a ,table showing the direction and rate of movement of several twining plants1 with a few appended remarks4 ,these plants are arranged according to ,lindley's #8,vegetable ,kingdom' of #ahec2 and they have been selected from all parts of the series so as to show that all kinds behave in a nearly uniform manner4 #bd ,the ,rate of ,revolution of various ,twining ,plants4 7,,acotyledons47 ,lygodium scandens 7,polypodiace7 moves against the sun4 ,h4 ,m4 ,june #ah1 #ast circle was made in #f #j #ah1 #bnd #f #ae 7late in evening7 #ai1 #crd #e #cb 7very hot day7 #ai1 #dth #e #j 7very hot day7 #bj1 #eth #f #j ,lygodium articulatum moves against the sun4 ,h4 ,m4 ,july #ai1 #ast circle was made in #af #cj 7shoot very young7 #bj1 #bnd #ae #j #ba1 #crd #h #j #bb1 #dth #aj #cj 7,,monocotyledons47 ,ruscus androgynus 7,liliace71 placed in the hot-house1 moves against the sun4 ,h4 ,m4 ,may #bd1 #ast circle was made in #f #ad 7shoot very young7 #be1 #bnd #b #ba #be1 #crd #c #cg #be1 #dth #c #bb #bf1 #eth #b #ej #bg1 #fth #c #eb #bg1 #gth #d #aa ,asparagus 7unnamed species from ,kew7 7,liliace7 moves against the sun1 placed in hothouse4 ,h4 ,m4 ,dec4 #bf1 #ast circle was made in #e #j #bg1 #bnd #e #dj ,tamus communis 7,dioscoreace74 ,a young shoot from a tuber in a pot placed in the greenhouse3 follows the sun4 ,h4 ,m4 ,july1 #g1 #ast circle was made in #c #aj #g1 #bnd #b #ch #h1 #crd #c #e #h1 #dth #b #ef #h1 #eth #b #cj #h1 #fth #b #cj ,lapagerea rosea 7,philesiace71 in greenhouse1 follows the sun4 ,h4 ,m4 ,march #i1 #ast circle was made in #bf #ae 7shoot young7 #aj1 semicircle #h #ae #aa1 #bnd circle #aa #j #ab1 #crd #ae #cj #ac1 #dth #ad #ae #af1 #eth #h #dj when placed in the hothouse2 but the next day the shoot remained stationary4 ,roxburghia viridiflora 7,roxburghiace7 moves against the sun2 it completed a circle in about #bd hours4 7,,dicotyledons47 ,humulus ,lupulus 7,urticace7 follows the sun4 ,the plant was kept in a room during warm weather4 ,h4 ,m4 ,april #i1 #b circles were made in #d #af ,aug4 #ac1 #crd circle was #b #j #ad1 #dth #b #bj #ad1 #eth #b #af #ad1 #fth #b #b #ad1 #gth #b #j #ad1 #hth #b #d ,with the ,hop a semicircle was performed1 in travelling from the light1 in #a hr4 #cc m42 in travelling to the light1 in #a hr4 #ac m42 difference of rate1 #bj m4 ,akebia quinata 7,lardizabalace71 placed in hothouse1 moves against the sun4 ,h4 ,m4 ,march #ag1 #ast circle was made in #d #j 7shoot young7 #ah1 #bnd #a #dj #ah1 #crd #a #cj #ai1 #dth #a #de ,stauntonia latifolia 7,lardizabalace71 placed in hothouse1 moves against the sun4 ,h4 ,m4 ,march #bh1 #ast circle was made in #c #cj #bi1 #bnd #c #de ,sphrostemma marmoratum 7,schizandrace7 follows the sun4 ,h4 ,m4 ,august #eth1 #ast circle was made in about #bd #j #eth1 #bnd circle was made in #ah #cj ,stephania rotunda 7,menispermace7 moves against the sun4 ,h4 ,m4 ,may #bg1 #ast circle was made in #e #e #cj1 #bnd #g #f ,june #b1 #crd #e #ae #c1 #dth #f #bh ,thryallis brachystachys 7,malpighiace7 moves against the sun3 one shoot made a circle in #ab hrs41 and another in #aj hrs4 #cj m42 but the next day1 which was much colder1 the first shoot took #aj hrs4 to perform only a semicircle4 ,hibbertia dentata 7,dilleniace71 placed in the hothouse1 followed the sun1 and made 7,may #ahth7 a circle in #g hrs4 #bj m42 on the #aith1 reversed its course1 and moved against the sun1 and made a circle in #g hrs42 on the #bjth1 moved against the sun one-third of a circle1 and then stood still2 on the #bfth1 followed the sun for two-thirds of a circle1 and then returned to its starting-point1 taking for this double course #aa hrs4 #df m4 ,sollya ,drummondii 7,pittosporace7 moves against the sun kept in greenhouse4 ,h4 ,m4 ,april #d1 #ast circle was made in #d #be #e1 #bnd #h #j 7very cold day7 #f1 #crd #f #be #g1 #dth #g #e ,polygonum dumetorum 7,polygonace74 ,this case is taken from ,dutrochet 7p4 #bii71 as ,i observed1 no allied plant3 follows the sun4 ,three shoots1 cut off a plant1 and placed in water made circles in #c hrs4 #aj m41 #e hrs4 #bj m41 and #g hrs4 #ae m4 ,wistaria ,chinensis 7,leguminos71 in greenhouse1 moves against the sun4 ,h4 ,m4 ,may #ac1 #ast circle was made in #c #e #ac1 #bnd #c #bj #af1 #crd #b #e #bd1 #dth #c #ba #be1 #eth #b #cg #be1 #fth #b #ce ,phaseolus vulgaris 7,leguminos71 in greenhouse1 moves against the sun4 ,h4 ,m4 ,may1 #ast circle was made in #b #j #bnd #a #ee #crd #a #ee ,dipladenia urophylla 7,apocynace7 moves against the sun4 ,h4 ,m4 ,april #ah1 #ast circle was made in #h #j #ai1 #bnd #i #ae #cj1 #crd #i #dj ,dipladenia crassinoda moves against the sun4 ,h4 ,m4 ,may #af1 #ast circle was made in #i #e ,july #bj1 #bnd #h #j #ba1 #crd #h #e ,ceropegia ,gardnerii 7,asclepiadace7 moves against the sun4 ,h4 ,m4 ,shoot very young1 #b inches in #ast circle was #g #ee length performed in ,shoot still young #bnd #g #j ,long shoot #crd #f #cc ,long shoot #dth #e #ae ,long shoot #eth #f #de ,stephanotis floribunda 7,asclepiadace7 moves against the sun and made a circle in #f hrs4 #dj m41 a second circle in about #i hrs4 ,hoya carnosa 7,asclepiadace7 made several circles in from #af hrs4 to #bb hrs4 or #bd hrs4 ,ipoma purpurea 7,convolvulace7 moves against the sun4 ,plant placed in room with lateral light4 #ast circle was made in #b hrs4 #db ,semicircle1 from the light in #a m4 hr4 #ad m41 to the light #a hr4 #bh m43 difference #ad m4 #bnd circle was made in #b hrs4 #dg ,semicircle1 from the light in #a m4 hr4 #ag m41 to the light #a hr4 #cj m43 difference #ac m4 ,ipoma jucunda 7,convolvulace7 moves against the sun1 placed in my study1 with windows facing the north-east4 ,weather hot4 #ast circle was made in #e hrs4 #cj ,semicircle1 from the light in #d m4 hrs4 #cj m41 to the light #a hr4 #j m43 difference #c hrs4 #cj m4 #bnd circle was made in #e hrs4 #bj ,semicircle1 from the light in #c m4 7,late in afternoon3 circle hrs4 #ej m41 to the light #a hr4 #cj completed at #f hrs4 #dj m4 ,p4,m47 m43 difference #b hrs4 #bj m4 ,we have here a remarkable instance of the power of light in retarding and hastening the revolving movement4 7,see ,,errata47 ,convolvulus sepium 7large-flowered cultivated var47 moves against the sun4 ,two circles1 were made each in #a hr4 #db m43 difference in semicircle from and to the light #ad m4 ,rivea tilifolia 7,convolvulace7 moves against the sun1 made four revolutions in #i hrs42 so that1 on an average1 each was performed in #b hrs4 #ae m4 ,plumbago rosea 7,plumbaginace7 follows the sun4 ,the shoot did not begin to revolve until nearly a yard in height2 it then made a fine circle in #aj hrs4 #de m4 ,during the next few days it continued to move1 but irregularly4 ,on ,august #aeth the shoot followed1 during a period of #aj hrs4 #dj m41 a long and deeply zigzag course and then made a broad ellipse4 ,the figure apparently represented three ellipses1 each of which averaged #c hrs4 #ch m4 for its completion4 ,jasminum pauciflorum1 ,bentham 7,jasminace71 moves against the sun4 ,a circle was made in #g hrs4 #ae m41 and a second rather more quickly4 ,clerodendrum ,thomsonii 7,verbenace7 follows the sun4 ,h4 ,m4 ,april #ab1 #ast circle was made in #e #de 7shoot very young7 #ad1 #bnd #c #cj #ah1 a semicircle #e #j 7directly after the plant was shaken on being moved7 #ai1 #crd circle #c #j #bj1 #dth #d #bj ,tecoma jasminoides 7,bignoniace7 moves against the sun4 ,h4 ,m4 ,march #ag1 #ast circle was made in #f #cj #ai1 #bnd #g #j #bb1 #crd #h #cj 7very cold day7 #bd1 #dth #f #de ,thunbergia alata 7,acanthace7 moves against sun4 ,h4 ,m4 ,april #ad1 #ast circle was made in #c #bj #ah1 #bnd #b #ej #ah1 #crd #b #ee #ah1 #dth #c #ee 7late in afternoon7 ,adhadota cydonfolia 7,acanthace7 follows the sun4 ,a young shoot made a semicircle in #bd hrs42 subsequently it made a circle in between #dj hrs4 and #dh hrs4 ,another shoot1 however1 made a circle in #bf hrs4 #cj m4 ,mikania scandens 7,composit7 moves against the sun4 ,h4 ,m4 ,march #ad1 #ast circle was made in #c #aj #ae1 #bnd #c #j #af1 #crd #c #j #ag1 #dth #c #cc ,april #g1 #eth #b #ej #g1 #fth #b #dj ,this circle was made after a copious watering with cold water at #dg ,fahr4 ,combretum argenteum 7,combretace7 moves against the sun4 ,kept in hothouse4 ,h4 ,m4 ,jan4 #bd1 #ast circle was made in #b #ee ,early in morning1 when the temperature of the house had fallen a little4 #bd1 #b circles each at an #b #bj average of #be1 #dth circle was made in #b #be ,combretum purpureum revolves not quite so quickly as ,c4 argenteum4 ,loasa aurantiaca 7,loasace74 ,revolutions variable in their course3 a plant which moved against the sun4 ,h4 ,m4 ,june #bj1 #ast circle was made in #b #cg #bj1 #bnd #b #ac #bj1 #crd #d #j #ba1 #dth #b #ce #bb1 #eth #c #bf #bc1 #fth #c #e ,another plant which followed the sun in its revolutions4 ,h4 ,m4 ,july #aa1 #ast circle was made in #a #ea ,very hot day4 #aa1 #bnd #a #df #aa1 #crd #a #da #aa1 #dth #a #dh #ab1 #eth #b #ce ,scyphanthus elegans 7,loasace7 follows the sun4 ,h4 ,m4 ,june #ac1 #ast circle was made in #a #de #ac1 #bnd #a #ag #ad1 #crd #a #cf #ad1 #dth #a #ei #ad1 #eth #b #c ,siphomeris or ,lecontea 7unnamed sp47 7,cinchonace7 follows the sun4 ,h4 ,m4 ,may #be1 semicircle was made in #aj #bg 7shoot extremely young7 #bf1 #ast circle #aj #ae 7shoot still young7 #cj1 #bnd #h #ee ,june #b1 #crd #h #aa #f1 #dth #f #h #h1 #eth #g #bj ,taken from the hothouse1 and placed in a room in my house4 #i1 #fth #h #cf ,manettia bicolor 7,cinchonace71 young plant1 follows the sun4 ,h4 ,m4 ,july #g1 #ast circle was made in #f #ah #h1 #bnd #f #ec #i1 #crd #f #cj ,lonicera brachypoda 7,caprifoliace7 follows the sun1 kept in a warm room in the house4 ,h4 ,m4 ,april1 #ast circle was made in #i #aj 7about7 ,april1 #bnd circle was made in #ab #bj 7a distinct shoot1 very young1 on same plant7 #crd #g #cj #dth #h #j ,in this latter circle1 the semicircle from the light took #e hrs4 #bc m41 and to the light #b hrs4 #cg min43 difference #b hrs #df m4 ,aristolochia gigas 7,aristolochiace7 moves against the sun4 ,h4 ,m4 ,july #bb1 #ast circle was made in #h #j 7rather young shoot7 #bc1 #bnd #g #ae #bd1 #crd #e #j 7about7 ,in the foregoing ,table1 which includes twining plants belonging to widely different orders1 we see that the rate at which growth travels or circulates round the axis 7on which the revolving movement depends71 differs much4 ,as long as a plant remains under the same conditions1 the rate is often remarkably uniform1 as with the ,hop1 ,mikania1 ,phaseolus1 c4 ,the ,scyphanthus made one revolution in #a hr4 #ag m41 and this is the quickest rate observed by me2 but we shall hereafter see a tendril-bearing ,passiflora revolving more rapidly4 ,a shoot of the ,akebia quinata made a revolution in #a hr4 #cj m41 and three revolutions at the average rate of #a hr4 #ch m42 a ,convolvulus made two revolutions at the average of #a hr4 #db m41 and ,phaseolus vulgaris three at the average of #a hr4 #eg m4 ,on the other hand1 some plants take #bd hrs4 for a single revolution1 and the ,adhadota sometimes required #dh hrs42 yet this latter plant is an efficient twiner4 ,species of the same genus move at different rates4 ,the rate does not seem governed by the thickness of the shoots3 those of the ,sollya are as thin and flexible as string1 but move more slowly than the thick and fleshy shoots of the ,ruscus1 which seem little fitted for movement of any kind4 ,the shoots of the ,wistaria1 which become woody1 move faster than those of the herbaceous ,ipomoea or ,thunbergia4 ,we know that the internodes1 whilst still very young1 do not acquire their proper rate of movement2 hence the several shoots on the same plant may sometimes be seen revolving at different rates4 ,the two or three1 or even more1 internodes which are first formed above the cotyledons1 or above the root-stock of a perennial plant1 do not move2 they can support themselves1 and nothing superfluous is granted4 ,a greater number of twiners revolve in a course opposed to that of the sun1 or to the hands of a watch1 than in the reversed course1 and1 consequently1 the majority1 as is well known1 ascend their supports from left to right4 ,occasionally1 though rarely1 plants of the same order twine in opposite directions1 of which ,mohl 7p4 #abe7 gives a case in the ,leguminos1 and we have in the table another in the ,acanthace4 ,i have seen no instance of two species of the same genus twining in opposite directions1 and such cases must be rare2 but ,fritz ,mller #cc states that although ,mikania scandens twines1 as ,i have described1 from left to right1 another species in ,south ,brazil twines in an opposite direction4 ,it would have been an anomalous circumstance if no such cases had occurred1 for different individuals of the same species1 namely1 of ,solanum dulcamara 7,dutrochet1 tom4 xix4 p4 #bii71 revolve and twine in two directions3 this plant1 however2 is a most feeble twiner4 ,loasa aurantiaca 7,lon1 p4 #cea7 offers a much more curious case3 ,i raised seventeen plants3 of these eight revolved in opposition to the sun and ascended from left to right2 five followed the sun and ascended from right to left2 and four revolved and twined first in one direction1 and then reversed their course1 #cd the petioles of the opposite leaves affording a point d'appui for the reversal of the spire4 ,one of these four plants made seven spiral turns from right to left1 and five turns from left to right4 ,another plant in the same family1 the ,scyphanthus elegans1 habitually twines in this same manner4 ,i raised many plants of it1 and the stems of all took one turn1 or occasionally two or even three turns in one direction1 and then1 ascending for a short space straight1 reversed their course and took one or two turns in an opposite direction4 ,the reversal of the curvature occurred at any point in the stem1 even in the middle of an internode4 ,had ,i not seen this case1 ,i should have thought its occurrence most improbable4 ,it would be hardly possible with any plant which ascended above a few feet in height1 or which lived in an exposed situation2 for the stem could be pulled away easily from its support1 with but little unwinding2 nor could it have adhered at all1 had not the internodes soon become moderately rigid4 ,with leaf-climbers1 as we shall soon see1 analogous cases frequently occur2 but these present no difficulty1 as the stem is secured by the clasping petioles4 ,in the many other revolving and twining plants observed by me1 ,i never but twice saw the movement reversed2 once1 and only for a short space1 in ,ipomoea jucunda2 but frequently with ,hibbertia dentata4 ,this plant at first perplexed me much1 for ,i continually observed its long and flexible shoots1 evidently well fitted for twining1 make a whole1 or half1 or quarter circle in one direction and then in an opposite direction2 consequently1 when ,i placed the shoots near thin or thick sticks1 or perpendicularly stretched string1 they seemed as if constantly trying to ascend1 but always failed4 ,i then surrounded the plant with a mass of branched twigs2 the shoots ascended1 and passed through them1 but several came out laterally1 and their depending extremities seldom turned upwards as is usual with twining plants4 ,finally1 ,i surrounded a second plant with many thin upright sticks1 and placed it near the first one with twigs2 and now both had got what they liked1 for they twined up the parallel sticks1 sometimes winding round one and sometimes round several2 and the shoots travelled laterally from one to the other pot2 but as the plants grew older1 some of the shoots twined regularly up thin upright sticks4 ,though the revolving movement was sometimes in one direction and sometimes in the other1 the twining was invariably from left to right2 #cf so that the more potent or persistent movement of revolution must have been in opposition to the course of the sun4 ,it would appear that this ,hibbertia is adapted both to ascend by twining1 and to ramble laterally through the thick ,australian scrub4 ,i have described the above case in some detail1 because1 as far as ,i have seen1 it is rare to find any special adaptations with twining plants1 in which respect they differ much from the more highly organized tendril-bearers4 ,the ,solanum dulcamara1 as we shall presently see1 can twine only round stems which are both thin and flexible4 ,most twining plants are adapted to ascend supports of moderate though of different thicknesses4 ,our ,english twiners1 as far as ,i have seen1 never twine round trees1 excepting the honeysuckle 7,lonicera periclymenum71 which ,i have observed twining up a young beech-tree nearly #d inches in diameter4 ,mohl 7p4 #acd7 found that the ,phaseolus multiflorus and ,ipomoea purpurea could not1 when placed in a room with the light entering on one side1 twine round sticks between #c and #d inches in diameter2 for this interfered1 in a manner presently to be explained1 with the revolving movement4 ,in the open air1 however1 the ,phaseolus twined round a support of the above thickness1 but failed in twining round one #i inches in diameter4 ,nevertheless1 some twiners of the warmer temperate regions can manage this latter degree of thickness2 for ,i hear from ,dr4 ,hooker that at ,kew the ,ruscus androgynus has ascended a column #i inches in diameter2 and although a ,wistaria grown by me in a small pot tried in vain for weeks to get round a post between #e and #f inches in thickness1 yet at ,kew a plant ascended a trunk above #f inches in diameter4 ,the tropical twiners1 on the other hand1 can ascend thicker trees2 ,i hear from ,drs4 ,thomson and ,hooker that this is the case with the ,butea parviflora1 one of the ,menispermace1 and with some ,dalbergias and other ,leguminos4 #cg ,this power would be necessary for any species which had to ascend by twining the large trees of a tropical forest2 otherwise they would hardly ever be able to reach the light4 ,in our temperate countries it would be injurious to the twining plants which die down every year if they were enabled to twine round trunks of trees1 for they could not grow tall enough in a single season to reach the summit and gain the light4 ,by what means certain twining plants are adapted to ascend only thin stems1 whilst others can twine round thicker ones1 ,i do not know4 ,it appeared to me probable that twining plants with very long revolving shoots would be able to ascend thick supports2 accordingly ,i placed ,ceropegia ,gardnerii near a post #f inches in diameter1 but the shoots entirely failed to wind round it2 their great length and power of movement merely aid them in finding a distant stem round which to twine4 ,the ,sphrostemma marmoratum is a vigorous tropical twiner2 and as it is a very slow revolver1 ,i thought that this latter circumstance might help it in ascending a thick support2 but though it was able to wind round a #f-;inch post1 it could do this only on the same level or plane1 and did not form a spire and thus ascend4 ,as ferns differ so much in structure from phanerogamic plants1 it may be worth while here to show that twining ferns do not differ in their habits from other twining plants4 ,in ,lygodium articulatum the two internodes of the stem 7properly the rachis7 which are first formed above the root-stock do not move2 the third from the ground revolves1 but at first very slowly4 ,this species is a slow revolver3 but ,l4 scandens made five revolutions1 each at the average rate of #e hrs4 #de m42 and this represents fairly well the usual rate1 taking quick and slow movers1 amongst phanerogamic plants4 ,the rate was accelerated by increased temperature4 ,at each stage of growth only the two upper internodes revolved4 ,a line painted along the convex surface of a revolving internode becomes first lateral1 then concave1 then lateral and ultimately again convex4 ,neither the internodes nor the petioles are irritable when rubbed4 ,the movement is in the usual direction1 namely1 in opposition to the course of the sun2 and when the stem twines round a thin stick1 it becomes twisted on its own axis in the same direction4 ,after the young internodes have twined round a stick1 their continued growth causes them to slip a little upwards4 ,if the stick be soon removed1 they straighten themselves1 and recommence revolving4 ,the extremities of the depending shoots turn upwards1 and twine on themselves4 ,in all these respects we have complete identity with twining phanerogamic plants2 and the above enumeration may serve as a summary of the leading characteristics of all twining plants4 ,the power of revolving depends on the general health and vigour of the plant1 as has been laboriously shown by ,palm4 ,but the movement of each separate internode is so independent of the others1 that cutting off an upper one does not affect the revolutions of a lower one4 ,when1 however1 ,dutrochet cut off two whole shoots of the ,hop1 and placed them in water1 the movement was greatly retarded2 for one revolved in #bj hrs4 and the other in #bc hrs41 whereas they ought to have revolved in between #b hrs4 and #b hrs4 #cj m4 ,shoots of the ,kidney-bean1 cut off and placed in water1 were similarly retarded1 but in a less degree4 ,i have repeatedly observed that carrying a plant from the greenhouse to my room1 or from one part to another of the greenhouse1 always stopped the movement for a time2 hence ,i conclude that plants in a state of nature and growing in exposed situations1 would not make their revolutions during very stormy weather4 ,a decrease in temperature always caused a considerable retardation in the rate of revolution2 but ,dutrochet 7tom4 xvii4 pp4 #iid1 #iif7 has given such precise observations on this head with respect to the common pea that ,i need say nothing more4 ,when twining plants are placed near a window in a room1 the light in some cases has a remarkable power 7as was likewise observed by ,dutrochet1 p4 #iih1 with the pea7 on the revolving movement1 but this differs in degree with different plants2 thus ,ipomoea jucunda made a complete circle in #e hrs4 #cj m42 the semicircle from the light taking #d hrs4 #hj m41 and that towards the light only #a hr4 ,lonicera brachypoda revolved1 in a reversed direction to the ,ipomoea1 in #h hrs42 the semicircle from the light taking #e hrs4 #bc m41 and that to the light only #b hrs4 #cg m4 ,from the rate of revolution in all the plants observed by me1 being nearly the same during the night and the day1 ,i infer that the action of the light is confined to retarding one semicircle and accelerating the other1 so as not to modify greatly the rate of the whole revolution4 ,this action of the light is remarkable1 when we reflect how little the leaves are developed on the young and thin revolving internodes4 ,it is all the more remarkable1 as botanists believe 7,mohl1 p4 #aai7 that twining plants are but little sensitive to the action of light4 ,i will conclude my account of twining plants by giving a few miscellaneous and curious cases4 ,with most twining plants all the branches1 however many there may be1 go on revolving together2 but1 according to ,mohl 7p4 #d71 only the lateral branches of ,tamus elephantipes twine1 and not the main stem4 ,on the other hand1 with a climbing species of ,asparagus1 the leading shoot alone1 and not the branches1 revolved and twined2 but it should be stated that the plant was not growing vigorously4 ,my plants of ,combretum argenteum and ,c4 purpureum made numerous short healthy shoots2 but they showed no signs of revolving1 and ,i could not conceive how these plants could be climbers2 but at last ,c4 argenteum put forth from the lower part of one of its main branches a thin shoot1 #e or #f feet in length1 differing greatly in appearance from the previous shoots1 owing to its leaves being little developed1 and this shoot revolved vigorously and twined4 ,so that this plant produces shoots of two kinds4 ,with ,periploca ,grca 7,palm1 p4 #dc7 the uppermost shoots alone twine4 ,polygonum convolvulus twines only during the middle of the summer 7,palm1 p4 #dc1 #id72 and plants growing vigorously in the autumn show no inclination to climb4 ,the majority of ,asclepiadace are twiners2 but ,asclepias nigra only 8in fertiliori solo incipit scandere subvolubili caule0 7,willdenow1 quoted and confirmed by ,palm1 p4 #da74 ,asclepias vincetoxicum does not regularly twine1 but occasionally does so 7,palm1 p4 #db2 ,mohl1 p4 #aab7 when growing under certain conditions4 ,so it is with two species of ,ceropegia1 as ,i hear from ,prof4 ,harvey1 for these plants in their native dry ,south ,african home generally grow erect1 from #f inches to #b feet in height1--a very few taller specimens showing some inclination to curve2 but when cultivated near ,dublin1 they regularly twined up sticks #e or #f feet in height4 ,most ,convolvulace are excellent twiners2 but in ,south ,africa ,ipomoea argyroides almost always grows erect and compact1 from about #ab to #ah inches in height1 one specimen alone in ,prof4 ,harvey's collection showing an evident disposition to twine4 ,on the other hand1 seedlings raised near ,dublin twined up sticks above #h feet in height4 ,these facts are remarkable2 for there can hardly be a doubt that in the dryer provinces of ,south ,africa these plants have propagated themselves for thousands of generations in an erect condition2 and yet they have retained during this whole period the innate power of spontaneously revolving and twining1 whenever their shoots become elongated under proper conditions of life4 ,most of the species of ,phaseolus are twiners2 but certain varieties of the ,p4 multiflorus produce 7,lon1 p4 #fha7 two kinds of shoots1 some upright and thick1 and others thin and twining4 ,i have seen striking instances of this curious case of variability in 8,fulmer's dwarf forcing-bean10 which occasionally produced a single long twining shoot4 ,solanum dulcamara is one of the feeblest and poorest of twiners3 it may often be seen growing as an upright bush1 and when growing in the midst of a thicket merely scrambles up between the branches without twining2 but when1 according to ,dutrochet 7tom4 xix4 p4 #bii71 it grows near a thin and flexible support1 such as the stem of a nettle1 it twines round it4 ,i placed sticks round several plants1 and vertically stretched strings close to others1 and the strings alone were ascended by twining4 ,the stem twines indifferently to the right or left4 ,some others species of ,solanum1 and of another genus1 viz4 ,habrothamnus1 belonging to the same family1 are described in horticultural works as twining plants1 but they seem to possess this faculty in a very feeble degree4 ,we may suspect that the species of these two genera have as yet only partially acquired the habit of twining4 ,on the other hand with ,tecoma radicans1 a member of a family abounding with twiners and tendril-bearers1 but which climbs1 like the ivy1 by the aid of rootlets1 we may suspect that a former habit of twining has been lost1 for the stem exhibited slight irregular movements which could hardly be accounted for by changes in the action of the light4 ,there is no difficulty in understanding how a spirally twining plant could graduate into a simple root-climber2 for the young internodes of ,bignonia ,tweedyana and of ,hoya carnosa revolve and twine1 but likewise emit rootlets which adhere to any fitting surface1 so that the loss of twining would be no great disadvantage and in some respects an advantage to these species1 as they would then ascend their supports in a more direct line4 #dd ,,chapter ,,ii4 ,,leaf-,,climbers4 ,plants which climb by the aid of spontaneously revolving and sensitive petioles--,clematis--,tropolum--,maurand ia1 flower-peduncles moving spontaneously and sensitive to a touch--,rhodochiton--,lophospermum--inte rnodes sensitive--,solanum1 thickening of the clasped petioles--,fumaria--,adlumia--,plants which climb by the aid of their produced midribs--,gloriosa--,flagellaria--,nepen thes--,summary on leaf-climbers4 ,,we now come to our second class of climbing plants1 namely1 those which ascend by the aid of irritable or sensitive organs4 ,for convenience' sake the plants in this class have been grouped under two sub-divisions1 namely1 leaf-climbers1 or those which retain their leaves in a functional condition1 and tendril-bearers4 ,but these sub-divisions graduate into each other1 as we shall see under ,corydalis and the ,gloriosa lily4 ,it has long been observed that several plants climb by the aid of their leaves1 either by their petioles 7foot-stalks7 or by their produced midribs2 but beyond this simple fact they have not been described4 ,palm and ,mohl class these plants with those which bear tendrils2 but as a leaf is generally a defined object1 the present classification1 though artificial1 has at least some advantages4 ,leaf-climbers are1 moreover1 intermediate in many respects between twiners and tendril-bearers4 ,eight species of ,clematis and seven of ,tropolum were observed1 in order to see what amount of difference in the manner of climbing existed within the same genus2 and the differences are considerable4 ,,clematis4--,c4 glandulosa4--,the thin upper internodes revolve1 moving against the course of the sun1 precisely like those of a true twiner1 at an average rate1 judging from three revolutions1 of #c hrs4 #dh m4 ,the leading shoot immediately twined round a stick placed near it2 but1 after making an open spire of only one turn and a half1 it ascended for a short space straight1 and then reversed its course and wound two turns in an opposite direction4 ,this was rendered possible by the straight piece between the opposed spires having become rigid4 ,the simple1 broad1 ovate leaves of this tropical species1 with their short thick petioles1 seem but ill-fitted for any movement2 and whilst twining up a vertical stick1 no use is made of them4 ,nevertheless1 if the footstalk of a young leaf be rubbed with a thin twig a few times on any side1 it will in the course of a few hours bend to that side2 afterwards becoming straight again4 ,the under side seemed to be the most sensitive2 but the sensitiveness or irritability is slight compared to that which we shall meet with in some of the following species2 thus1 a loop of string1 weighing #a4fd grain 7#ajf4b mg47 and hanging for some days on a young footstalk1 produced a scarcely perceptible effect4 ,a sketch is here given of two young leaves which had naturally caught hold of two thin branches4 ,a forked twig placed so as to press lightly on the under side of a young footstalk caused it1 in #ab hrs41 to bend greatly1 and ultimately to such an extent that the leaf passed to the opposite side of the stem2 the forked stick having been removed1 the leaf slowly recovered its former position4 ,picture3 ,fig4 #a4 ,clematis glandulosa4 ,with two young leaves clasping two twigs1 with the clasping portions thickened ,the young leaves spontaneously and gradually change their position3 when first developed the petioles are upturned and parallel to the stem2 they then slowly bend downwards1 remaining for a short time at right angles to the stem1 and then become so much arched downwards that the blade of the leaf points to the ground with its tip curled inwards1 so that the whole petiole and leaf together form a hook4 ,they are thus enabled to catch hold of any twig with which they may be brought into contact by the revolving movement of the internodes4 ,if this does not happen1 they retain their hooked shape for a considerable time1 and then bending upwards reassume their original upturned position1 which is preserved ever afterwards4 ,the petioles which have clasped any object soon become much thickened and strengthened1 as may be seen in the drawing4 ,clematis montana4--,the long1 thin petioles of the leaves1 whilst young1 are sensitive1 and when lightly rubbed bend to the rubbed side1 subsequently becoming straight4 ,they are far more sensitive than the petioles of ,c4 glandulosa2 for a loop of thread weighing a quarter of a grain 7#af4b mg47 caused them to bend2 a loop weighing only one-eighth of a grain 7#h4a mg47 sometimes acted and sometimes did not act4 ,the sensitiveness extends from the blade of the leaf to the stem4 ,i may here state that ,i ascertained in all cases the weights of the string and thread used by carefully weighing #ej inches in a chemical balance1 and then cutting off measured lengths4 ,the main petiole carries three leaflets2 but their short1 sub-petioles are not sensitive4 ,a young1 inclined shoot 7the plant being in the greenhouse7 made a large circle opposed to the course of the sun in #d hrs4 #bj m41 but the next day1 being very cold1 the time was #e hrs4 #aj m4 ,a stick placed near a revolving stem was soon struck by the petioles which stand out at right angles1 and the revolving movement was thus arrested4 ,the petioles then began1 being excited by the contact1 to slowly wind round the stick4 ,when the stick was thin1 a petiole sometimes wound twice round it4 ,the opposite leaf was in no way affected4 ,the attitude assumed by the stem after the petiole had clasped the stick1 was that of a man standing by a column1 who throws his arm horizontally round it4 ,with respect to the stem's power of twining1 some remarks will be made under ,c4 calycina4 ,clematis ,sieboldi4--,a shoot made three revolutions against the sun at an average rate of #c hrs4 #aa m4 ,the power of twining is like that of the last species4 ,its leaves are nearly similar in structure and in function1 excepting that the sub-petioles of the lateral and terminal leaflets are sensitive4 ,a loop of thread1 weighing one-eighth of a grain1 acted on the main petiole1 but not until two or three days had elapsed4 ,the leaves have the remarkable habit of spontaneously revolving1 generally in vertical ellipses1 in the same manner1 but in a less degree1 as will be described under ,c4 microphylla4 ,clematis calycina4--,the young shoots are thin and flexible3 one revolved1 describing a broad oval1 in #e hrs4 #cj m41 and another in #f hrs4 #ab m4 ,they followed the course of the sun2 but the course1 if observed long enough1 would probably be found to vary in this species1 as well as in all the others of the genus4 ,it is a rather better twiner than the two last species3 the stem sometimes made two spiral turns round a thin stick1 if free from twigs2 it then ran straight up for a space1 and reversing its course took one or two turns in an opposite direction4 ,this reversal of the spire occurred in all the foregoing species4 ,the leaves are so small compared with those of most of the other species1 that the petioles at first seem ill-adapted for clasping4 ,nevertheless1 the main service of the revolving movement is to bring them into contact with surrounding objects1 which are slowly but securely seized4 ,the young petioles1 which alone are sensitive1 have their ends bowed a little downwards1 so as to be in a slight degree hooked2 ultimately the whole leaf1 if it catches nothing1 becomes level4 ,i gently rubbed with a thin twig the lower surfaces of two young petioles2 and in #b hrs4 #cj m4 they were slightly curved downwards2 in #e hrs41 after being rubbed1 the end of one was bent completely back1 parallel to the basal portion2 in #d hrs4 subsequently it became nearly straight again4 ,to show how sensitive the young petioles are1 ,i may mention that ,i just touched the under sides of two with a little water-colour1 which when dry formed an excessively thin and minute crust2 but this sufficed in #bd hrs4 to cause both to bend downwards4 ,whilst the plant is young1 each leaf consists of three divided leaflets1 which barely have distinct petioles1 and these are not sensitive2 but when the plant is well grown1 the petioles of the two lateral and terminal leaflets are of considerable length1 and become sensitive so as to be capable of clasping an object in any direction4 ,when a petiole has clasped a twig1 it undergoes some remarkable changes1 which may be observed with the other species1 but in a less strongly marked manner1 and will here be described once for all4 ,the clasped petiole in the course of two or three days swells greatly1 and ultimately becomes nearly twice as thick as the opposite one which has clasped nothing4 ,when thin transverse slices of the two are placed under the microscope their difference is conspicuous3 the side of the petiole which has been in contact with the support1 is formed of a layer of colourless cells with their longer axes directed from the centre1 and these are very much larger than the corresponding cells in the opposite or unchanged petiole2 the central cells1 also1 are in some degree enlarged1 and the whole is much indurated4 ,the exterior surface generally becomes bright red4 ,but a far greater change takes place in the nature of the tissues than that which is visible3 the petiole of the unclasped leaf is flexible and can be snapped easily1 whereas the clasped one acquires an extraordinary degree of toughness and rigidity1 so that considerable force is required to pull it into pieces4 ,with this change1 great durability is probably acquired2 at least this is the case with the clasped petioles of ,clematis vitalba4 ,the meaning of these changes is obvious1 namely1 that the petioles may firmly and durably support the stem4 ,clematis microphylla1 var4 leptophylla4--,the long and thin internodes of this ,australian species revolve sometimes in one direction and sometimes in an opposite one1 describing long1 narrow1 irregular ellipses or large circles4 ,four revolutions were completed within five minutes of the same average rate of #a hr4 #ea m42 so that this species moves more quickly than the others of the genus4 ,the shoots1 when placed near a vertical stick1 either twine round it1 or clasp it with the basal portions of their petioles4 ,the leaves whilst young are nearly of the same shape as those of ,c4 viticella1 and act in the same manner like a hook1 as will be described under that species4 ,but the leaflets are more divided1 and each segment whilst young terminates in a hardish point1 which is much curved downwards and inwards2 so that the whole leaf readily catches hold of any neighbouring object4 ,the petioles of the young terminal leaflets are acted on by loops of thread weighing th and even #j4jfbeth of a grain4 ,the basal portion of the main petiole is much less sensitive1 but will clasp a stick against which it presses4 ,the leaves1 whilst young1 are continually and spontaneously moving slowly4 ,a bell-glass was placed over a shoot secured to a stick1 and the movements of the leaves were traced on it during several days4 ,a very irregular line was generally formed2 but one day1 in the course of eight hours and three quarters1 the figure clearly represented three and a half irregular ellipses1 the most perfect one of which was completed in #b hrs4 #ce m4 ,the two opposite leaves moved independently of each other4 ,this movement of the leaves would aid that of the internodes in bringing the petioles into contact with surrounding objects4 ,i discovered this movement too late to be enabled to observe it in the other species2 but from analogy ,i can hardly doubt that the leaves of at least ,c4 viticella1 ,c4 flammula1 and ,c4 vitalba move spontaneously2 and1 judging from ,c4 ,sieboldi1 this probably is the case with ,c4 montana and ,c4 calycina4 ,i ascertained that the simple leaves of ,c4 glandulosa exhibited no spontaneous revolving movement4 ,clematis viticella1 var4 venosa4--,in this and the two following species the power of spirally twining is completely lost1 and this seems due to the lessened flexibility of the internodes and to the interference caused by the large size of the leaves4 ,but the revolving movement1 though restricted1 is not lost4 ,in our present species a young internode1 placed in front of a window1 made three narrow ellipses1 transversely to the direction of the light1 at an average rate of #b hrs4 #dj m4 ,when placed so that the movements were to and from the light1 the rate was greatly accelerated in one half of the course1 and retarded in the other1 as with twining plants4 ,the ellipses were small2 the longer diameter1 described by the apex of a shoot bearing a pair of not expanded leaves1 was only #d inches1 and that by the apex of the penultimate internode only #a inch4 ,at the most favourable period of growth each leaf would hardly be carried to and fro by the movement of the internodes more than two or three inches1 but1 as above stated1 it is probable that the leaves themselves move spontaneously4 ,the movement of the whole shoot by the wind and by its rapid growth1 would probably be almost equally efficient as these spontaneous movements1 in bringing the petioles into contact with surrounding objects4 ,the leaves are of large size4 ,each bears three pairs of lateral leaflets and a terminal one1 all supported on rather long sub-petioles4 ,the main petiole bends a little angularly downwards at each point where a pair of leaflets arises 7see fig4 #b71 and the petiole of the terminal leaflet is bent downwards at right angles2 hence the whole petiole1 with its rectangularly bent extremity1 acts as a hook4 ,this hook1 the lateral petioles being directed a little upwards2 forms an excellent grappling apparatus1 by which the leaves readily become entangled with surrounding objects4 ,if they catch nothing1 the whole petiole ultimately grows straight4 ,the main petiole1 the sub-petioles1 and the three branches into which each basi-lateral sub-petiole is generally subdivided1 are all sensitive4 ,the basal portion of the main petiole1 between the stem and the first pair of leaflets1 is less sensitive than the remainder2 it will1 however1 clasp a stick with which it is left in contact4 ,the inferior surface of the rectangularly bent terminal portion 7carrying the terminal leaflet71 which forms the inner side of the end of the hook1 is the most sensitive part2 and this portion is manifestly best adapted to catch a distant support4 ,to show the difference in sensibility1 ,i gently placed loops of string of the same weight 7in one instance weighing only #j4hb of a grain or #ec4ad mg47 on the several lateral sub-petioles and on the terminal one2 in a few hours the latter was bent1 but after #bd hrs4 no effect was produced on the other sub-petioles4 ,again1 a terminal sub-petiole placed in contact with a thin stick became sensibly curved in #de m41 and in #a hr4 #aj m4 moved through ninety degrees2 whilst a lateral sub-petiole did not become sensibly curved until #c hrs4 #cj m4 had elapsed4 ,in all cases1 if the sticks are taken away1 the petioles continue to move during many hours afterwards2 so they do after a slight rubbing2 but they become straight again1 after about a day's interval1 that is if the flexure has not been very great or long continued4 ,picture3 ,fig4 #b4 ,a young leaf of ,clematis viticeela ,the graduated difference in the extension of the sensitiveness in the petioles of the above-described species deserves notice4 ,in ,c4 montana it is confined to the main petiole1 and has not spread to the sub-petioles of the three leaflets2 so it is with young plants of ,c4 calycina1 but in older plants it spreads to the three sub-petioles4 ,in ,c4 viticella the sensitiveness has spread to the petioles of the seven leaflets1 and to the subdivisions of the basi-lateral sub-petioles4 ,but in this latter species it has diminished in the basal part of the main petiole1 in which alone it resided in ,c4 montana2 whilst it has increased in the abruptly bent terminal portion4 ,clematis flammula4--,the rather thick1 straight1 and stiff shoots1 whilst growing vigorously in the spring1 make small oval revolutions1 following the sun in their course4 ,four were made at an average rate of #c hrs4 #de m4 ,the longer axis of the oval1 described by the extreme tip1 was directed at right angles to the line joining the opposite leaves2 its length was in one case only #a1 and in another case #a inch2 so that the young leaves were moved a very short distance4 ,the shoots of the same plant observed in midsummer1 when growing not so quickly1 did not revolve at all4 ,i cut down another plant in the early summer1 so that by ,august #ast it had formed new and moderately vigorous shoots2 these1 when observed under a bell-glass1 were on some days quite stationary1 and on other days moved to and fro only about the eighth of an inch4 ,consequently the revolving power is much enfeebled in this species1 and under unfavourable circumstances is completely lost4 ,the shoot must depend for coming into contact with surrounding objects on the probable1 though not ascertained spontaneous movement of the leaves1 on rapid growth1 and on movement from the wind4 ,hence1 perhaps1 it is that the petioles have acquired a high degree of sensitiveness as a compensation for the little power of movement in the shoots4 ,the petioles are bowed downwards1 and have the same general hook-like form as in ,c4 viticella4 ,the medial petiole and the lateral sub-petioles are sensitive1 especially the much bent terminal portion4 ,as the sensitiveness is here greater than in any other species of the genus observed by me1 and is in itself remarkable1 ,i will give fuller details4 ,the petioles1 when so young that they have not separated from one another1 are not sensitive2 when the lamina of a leaflet has grown to a quarter of an inch in length 7that is1 about one-sixth of its full size71 the sensitiveness is highest2 but at this period the petioles are relatively much more fully developed than are the blades of the leaves4 ,full-grown petioles are not in the least sensitive4 ,a thin stick placed so as to press lightly against a petiole1 having a leaflet a quarter of an inch in length1 caused the petiole to bend in #c hrs4 #ae m4 ,in another case a petiole curled completely round a stick in #ab hrs4 ,these petioles were left curled for #bd hrs41 and the sticks were then removed2 but they never straightened themselves4 ,i took a twig1 thinner than the petiole itself1 and with it lightly rubbed several petioles four times up and down2 these in #a hr4 #de m4 became slightly curled2 the curvature increased during some hours and then began to decrease1 but after #be hrs4 from the time of rubbing a vestige of the curvature remained4 ,some other petioles similarly rubbed twice1 that is1 once up and once down1 became perceptibly curved in about #b hrs4 #cj m41 the terminal sub-petiole moving more than the lateral sub-petioles2 they all became straight again in between #ab hrs4 and #ad hrs4 ,lastly1 a length of about one-eighth of an inch of a sub-petiole1 was lightly rubbed with the same twig only once2 it became slightly curved in #c hrs41 remaining so during #aa hrs41 but by the next morning was quite straight4 ,the following observations are more precise4 ,after trying heavier pieces of string and thread1 ,i placed a loop of fine string1 weighing #a4jd gr4 7#fg4d mg47 on a terminal sub-petiole3 in #f hrs4 #dj m4 a curvature could be seen2 in #bd hrs4 the petiole formed an open ring round the string2 in #dh hrs4 the ring had almost closed on the string1 and in #gb hrs4 seized it so firmly1 that some force was necessary for its withdrawal4 ,a loop weighing #j4eb of a grain 7#cc4g mg47 caused in #ad hrs4 a lateral sub-petiole just perceptibly to curve1 and in #bd hrs4 it moved through ninety degrees4 ,these observations were made during the summer3 the following were made in the spring1 when the petioles apparently are more sensitive3--,a loop of thread1 weighing one-eighth of a grain 7#h4a mg471 produced no effect on the lateral sub-petioles1 but placed on a terminal one1 caused it1 after #bd hrs41 to curve moderately2 the curvature1 though the loop remained suspended1 was after #dh hrs4 diminished1 but never disappeared2 showing that the petiole had become partially accustomed to the insufficient stimulus4 ,this experiment was twice repeated with nearly the same result4 ,lastly1 a loop of thread1 weighing only one-sixteenth of a grain 7#d4je mg47 was twice gently placed by a forceps on a terminal sub-petiole 7the plant being1 of course1 in a still and closed room71 and this weight certainly caused a flexure1 which very slowly increased until the petiole moved through nearly ninety degrees3 beyond this it did not move2 nor did the petiole1 the loop remaining suspended1 ever become perfectly straight again4 ,when we consider1 on the one hand1 the thickness and stiffness of the petioles1 and1 on the other hand1 the thinness and softness of fine cotton thread1 and what an extremely small weight one-sixteenth of a grain 7#d4je mg47 is1 these facts are remarkable4 ,but ,i have reason to believe that even a less weight excites curvature when pressing over a broader surface than that acted on by a thread4 ,having noticed that the end of a suspended string which accidentally touched a petiole1 caused it to bend1 ,i took two pieces of thin twine1 #aj inches in length 7weighing #a4fd gr471 and1 tying them to a stick1 let them hang as nearly perpendicularly downwards as their thinness and flexuous form1 after being stretched1 would permit2 ,i then quietly placed their ends so as just to rest on two petioles1 and these certainly became curved in #cf hrs4 ,one of the ends touched the angle between a terminal and lateral sub-petiole1 and it was in #dh hours caught between them as by a forceps4 ,in these cases the pressure1 though spread over a wider surface than that touched by the cotton thread1 must have been excessively slight4 ,clematis vitalba4--,the plants were in pots and not healthy1 so that ,i dare not trust my observations1 which indicate much similarity in habits with ,c4 flammula4 ,i mention this species only because ,i have seen many proofs that the petioles in a state of nature are excited to movement by very slight pressure4 ,for instance1 ,i have found them embracing thin withered blades of grass1 the soft young leaves of a maple1 and the flower-peduncles of the quaking-grass or ,briza4 ,the latter are about as thick as the hair of a man's beard1 but they were completely surrounded and clasped4 ,the petioles of a leaf1 so young that none of the leaflets were expanded1 had partially seized a twig4 ,those of almost all the old leaves1 even when unattached to any object1 are much convoluted2 but this is owing to their having come1 whilst young1 into contact during several hours with some object subsequently removed4 ,with none of the above-described species1 cultivated in pots and carefully observed1 was there any permanent bending of the petioles without the stimulus of contact4 ,in winter1 the blades of the leaves of ,c4 vitalba drop off2 but the petioles 7as was observed by ,mohl7 remain attached to the branches1 sometimes during two seasons2 and1 being convoluted1 they curiously resemble true tendrils1 such as those possessed by the allied genus ,naravelia4 ,the petioles which have clasped some object become much more stiff1 hard1 and polished than those which have failed in this their proper function4 ,,trop,,olum4--,i observed ,t4 tricolorum1 ,t4 azureum1 ,t4 pentaphyllum1 ,t4 peregrinum1 ,t4 elegans1 ,t4 tuberosum1 and a dwarf variety of1 as ,i believe1 ,t4 minus4 ,tropolum tricolorum1 var4 grandiflorum4--,the flexible shoots1 which first rise from the tubers1 are as thin as fine twine4 ,one such shoot revolved in a course opposed to the sun1 at an average rate1 judging from three revolutions1 of #a hr4 #bc m42 but no doubt the direction of the revolving movement is variable4 ,when the plants have grown tall and are branched1 all the many lateral shoots revolve4 ,the stem1 whilst young1 twines regularly round a thin vertical stick1 and in one case ,i counted eight spiral turns in the same direction2 but when grown older1 the stem often runs straight up for a space1 and1 being arrested by the clasping petioles1 makes one or two spires in a reversed direction4 ,until the plant grows to a height of two or three feet1 requiring about a month from the time when the first shoot appears above ground1 no true leaves are produced1 but1 in their place1 filaments coloured like the stem4 ,the extremities of these filaments are pointed1 a little flattened1 and furrowed on the upper surface4 ,they never become developed into leaves4 ,as the plant grows in height new filaments are produced with slightly enlarged tips2 then others1 bearing on each side of the enlarged medial tip a rudimentary segment of a leaf2 soon other segments appear1 and at last a perfect leaf is formed1 with seven deep segments4 ,so that on the same plant we may see every step1 from tendril-like clasping filaments to perfect leaves with clasping petioles4 ,after the plant has grown to a considerable height1 and is secured to its support by the petioles of the true leaves1 the clasping filaments on the lower part of the stem wither and drop off2 so that they perform only a temporary service4 ,these filaments or rudimentary leaves1 as well as the petioles of the perfect leaves1 whilst young1 are highly sensitive on all sides to a touch4 ,the slightest rub caused them to curve towards the rubbed side in about three minutes1 and one bent itself into a ring in six minutes2 they subsequently became straight4 ,when1 however1 they have once completely clasped a stick1 if this is removed1 they do not straighten themselves4 ,the most remarkable fact1 and one which ,i have observed in no other species of the genus1 is that the filaments and the petioles of the young leaves1 if they catch no object1 after standing for some days in their original position1 spontaneously and slowly oscillate a little from side to side1 and then move towards the stem and clasp it4 ,they likewise often become1 after a time1 in some degree spirally contracted4 ,they therefore fully deserve to be called tendrils1 as they are used for climbing1 are sensitive to a touch1 move spontaneously1 and ultimately contract into a spire1 though an imperfect one4 ,the present species would have been classed amongst the tendril-bearers1 had not these characters been confined to early youth4 ,during maturity it is a true leaf-climber4 ,tropolum azureum4--,an upper internode made four revolutions1 following the sun1 at an average rate of #a hr4 #dg m4 ,the stem twined spirally round a support in the same irregular manner as that of the last species4 ,rudimentary leaves or filaments do not exist4 ,the petioles of the young leaves are very sensitive3 a single light rub with a twig caused one to move perceptibly in #e m41 and another in #f m4 ,the former became bent at right angles in #ae min41 and became straight again in between #e hrs4 and #f hrs4 ,a loop of thread weighing th of a grain caused another petiole to curve4 ,tropolum pentaphyllum4--,this species has not the power of spirally twining1 which seems due1 not so much to a want of flexibility in the stem1 as to continual interference from the clasping petioles4 ,an upper internode made three revolutions1 following the sun1 at an average rate of #a hr4 #df m4 ,the main purpose of the revolving movement in all the species of ,tropolum manifestly is to bring the petioles into contact with some supporting object4 ,the petiole of a young leaf1 after a slight rub1 became curved in #f m42 another1 on a cold day1 in #bj m41 and others in from #h m4 to #aj m4 ,their curvature usually increased greatly in from #ae m4 to #bj m41 and they became straight again in between #e hrs4 and #f hrs41 but on one occasion in #c hrs4 ,when a petiole has fairly clasped a stick1 it is not able1 on the removal of the stick1 to straighten itself4 ,the free upper part of one1 the base of which had already clasped a stick1 still retained the power of movement4 ,a loop of thread weighing th of a grain caused a petiole to curve2 but the stimulus was not sufficient1 the loop remaining suspended1 to cause a permanent flexure4 ,if a much heavier loop be placed in the angle between the petiole and the stem1 it produces no effect2 whereas we have seen with ,clematis montana that the angle between the stem and petiole is sensitive4 ,tropolum peregrinum4--,the first-formed internodes of a young plant did not revolve1 resembling in this respect those of a twining plant4 ,in an older plant the four upper internodes made three irregular revolutions1 in a course opposed to the sun1 at an average rate of #a hr4 #dh min4 ,it is remarkable that the average rate of revolution 7taken1 however1 but from few observations7 is very nearly the same in this and the two last species1 namely1 #a hr4 #dg m41 #a hr4 #df m41 and #a hr4 #dh m4 ,the present species cannot twine spirally1 which seems mainly due to the rigidity of the stem4 ,in a very young plant1 which did not revolve1 the petioles were not sensitive4 ,in older plants the petioles of quite young leaves1 and of leaves as much as an inch and a quarter in diameter1 are sensitive4 ,a moderate rub caused one to curve in #aj m41 and others in #bj m4 ,they became straight again in between #e hrs4 #de m4 and #h hrs4 ,petioles which have naturally come into contact with a stick1 sometimes take two turns round it4 ,after they have clasped a support1 they become rigid and hard4 ,they are less sensitive to a weight than in the previous species2 for loops of string weighing #j4hb of a grain 7#ec4ad mg471 did not cause any curvature1 but a loop of double this weight 7#a4fd gr47 acted4 ,tropolum elegans4--,i did not make many observations on this species4 ,the short and stiff internodes revolve irregularly1 describing small oval figures4 ,one oval was completed in #c hrs4 ,a young petiole1 when rubbed1 became slightly curved in #ag m42 and afterwards much more so4 ,it was nearly straight again in #h hrs4 ,tropolum tuberosum4--,on a plant nine inches in height1 the internodes did not move at all2 but on an older plant they moved irregularly and made small imperfect ovals4 ,these movements could be detected only by being traced on a bell-glass placed over the plant4 ,sometimes the shoots stood still for hours2 during some days they moved only in one direction in a crooked line2 on other days they made small irregular spires or circles1 one being completed in about #d hrs4 ,the extreme points reached by the apex of the shoot were only about one or one and a half inches asunder2 yet this slight movement brought the petioles into contact with some closely surrounding twigs1 which were then clasped4 ,with the lessened power of spontaneously revolving1 compared with that of the previous species1 the sensitiveness of the petioles is also diminished4 ,these1 when rubbed a few times1 did not become curved until half an hour had elapsed2 the curvature increased during the next two hours1 and then very slowly decreased2 so that they sometimes required #bd hrs4 to become straight again4 ,extremely young leaves have active petioles2 one with the lamina only #j4ae of an inch in diameter1 that is1 about a twentieth of the full size1 firmly clasped a thin twig4 ,but leaves grown to a quarter of their full size can likewise act4 ,tropolum minus 7874--,the internodes of a variety named 8dwarf crimson ,nasturtium0 did not revolve1 but moved in a rather irregular course during the day to the light1 and from the light at night4 ,the petioles1 when well rubbed1 showed no power of curving2 nor could ,i see that they ever clasped any neighbouring object4 ,we have seen in this genus a gradation from species such as ,t4 tricolorum1 which have extremely sensitive petioles1 and internodes which rapidly revolve and spirally twine up a support1 to other species such as ,t4 elegans and ,t4 tuberosum1 the petioles of which are much less sensitive1 and the internodes of which have very feeble revolving powers and cannot spirally twine round a support1 to this last species1 which has entirely lost or never acquired these faculties4 ,from the general character of the genus1 the loss of power seems the more probable alternative4 ,in the present species1 in ,t4 elegans1 and probably in others1 the flower-peduncle1 as soon as the seed-capsule begins to swell1 spontaneously bends abruptly downwards and becomes somewhat convoluted4 ,if a stick stands in the way1 it is to a certain extent clasped2 but1 as far as ,i have been able to observe1 this clasping movement is independent of the stimulus from contact4 ,,antirrhine4--,in this tribe 7,lindley7 of the ,scrophulariace1 at least four of the seven included genera have leaf-climbing species4 ,maurandia ,barclayana4--,a thin1 slightly bowed shoot made two revolutions1 following the sun1 each in #c hrs4 #ag min42 on the previous day this same shoot revolved in an opposite direction4 ,the shoots do not twine spirally1 but climb excellently by the aid of their young and sensitive petioles4 ,these petioles1 when lightly rubbed1 move after a considerable interval of time1 and subsequently become straight again4 ,a loop of thread weighing th of a grain caused them to bend4 ,maurandia semperflorens4--,this freely growing species climbs exactly like the last1 by the aid of its sensitive petioles4 ,a young internode made two circles1 each in #a hr4 #df min42 so that it moved almost twice as rapidly as the last species4 ,the internodes are not in the least sensitive to a touch or pressure4 ,i mention this because they are sensitive in a closely allied genus1 namely1 ,lophospermum4 ,the present species is unique in one respect4 ,mohl asserts 7p4 #de7 that 8the flower-peduncles1 as well as the petioles1 wind like tendrils20 but he classes as tendrils such objects as the spiral flower-stalks of the ,vallisneria4 ,this remark1 and the fact of the flower-peduncles being decidedly flexuous1 led me carefully to examine them4 ,they never act as true tendrils2 ,i repeatedly placed thin sticks in contact with young and old peduncles1 and ,i allowed nine vigorous plants to grow through an entangled mass of branches2 but in no one instance did they bend round any object4 ,it is indeed in the highest degree improbable that this should occur1 for they are generally developed on branches which have already securely clasped a support by the petioles of their leaves2 and when borne on a free depending branch1 they are not produced by the terminal portion of the internode which alone has the power of revolving2 so that they could be brought only by accident into contact with any neighbouring object4 ,nevertheless 7and this is the remarkable fact7 the flower-peduncles1 whilst young1 exhibit feeble revolving powers1 and are slightly sensitive to a touch4 ,having selected some stems which had firmly clasped a stick by their petioles1 and having placed a bell-glass over them1 ,i traced the movements of the young flower-peduncles4 ,the tracing generally formed a short and extremely irregular line1 with little loops in its course4 ,a young peduncle #a inch in length was carefully observed during a whole day1 and it made four and a half narrow1 vertical1 irregular1 and short ellipses--each at an average rate of about #b hrs4 #be m4 ,an adjoining peduncle described during the same time similar1 though fewer1 ellipses4 ,as the plant had occupied for some time exactly the same position1 these movements could not be attributed to any change in the action of the light4 ,peduncles1 old enough for the coloured petals to be just visible1 do not move4 ,with respect to irritability1 #fh ,i rubbed two young peduncles 7#a inch in length7 a few times very lightly with a thin twig2 one was rubbed on the upper1 and the other on the lower side1 and they became in between #d hrs4 and #e hrs4 distinctly bowed towards these sides2 in #bd hrs4 subsequently1 they straightened themselves4 ,next day they were rubbed on the opposite sides1 and they became perceptibly curved towards these sides4 ,two other and younger peduncles 7three-fourths of an inch in length7 were lightly rubbed on their adjoining sides1 and they became so much curved towards one another1 that the arcs of the bows stood at nearly right angles to their previous direction2 and this was the greatest movement seen by me4 ,subsequently they straightened themselves4 ,other peduncles1 so young as to be only three-tenths of an inch in length1 became curved when rubbed4 ,on the other hand1 peduncles above #a inch in length required to be rubbed two or three times1 and then became only just perceptibly bowed4 ,loops of thread suspended on the peduncles produced no effect2 loops of string1 however1 weighing #j4hb and #a4fd of a grain sometimes caused a slight curvature2 but they were never closely clasped1 as were the far lighter loops of thread by the petioles4 ,in the nine vigorous plants observed by me1 it is certain that neither the slight spontaneous movements nor the slight sensitiveness of the flower-peduncles aided the plants in climbing4 ,if any member of the ,scrophulariace had possessed tendrils produced by the modification of flower-peduncles1 ,i should have thought that this species of ,maurandia had perhaps retained a useless or rudimentary vestige of a former habit2 but this view cannot be maintained4 ,we may suspect that1 owing to the principle of correlation1 the power of movement has been transferred to the flower-peduncles from the young internodes1 and sensitiveness from the young petioles4 ,but to whatever cause these capacities are due1 the case is interesting2 for1 by a little increase in power through natural selection1 they might easily have been rendered as useful to the plant in climbing1 as are the flower-peduncles 7hereafter to be described7 of ,vitis or ,cardiospermum4 ,rhodochiton volubile4--,a long flexible shoot swept a large circle1 following the sun1 in #e hrs4 #cj m42 and1 as the day became warmer1 a second circle was completed in #d hrs4 #aj m4 ,the shoots sometimes make a whole or a half spire round a vertical stick1 they then run straight up for a space1 and afterwards turn spirally in an opposite direction4 ,the petioles of very young leaves about one-tenth of their full size1 are highly sensitive1 and bend towards the side which is touched2 but they do not move quickly4 ,one was perceptibly curved in #a hr4 #aj m41 after being lightly rubbed1 and became considerably curved in #e hrs4 #dj m42 some others were scarcely curved in #e hrs4 #cj m41 but distinctly so in #f hrs4 #cj m4 ,a curvature was perceptible in one petiole in between #d hrs4 #cj m4 and #e hrs41 after the suspension of a little loop of string4 ,a loop of fine cotton thread1 weighing one sixteenth of a grain 7#d4je mg471 not only caused a petiole slowly to bend1 but was ultimately so firmly clasped that it could be withdrawn only by some little force4 ,the petioles1 when coming into contact with a stick1 take either a complete or half a turn round it1 and ultimately increase much in thickness4 ,they do not possess the power of spontaneously revolving4 ,lophospermum scandens1 var4 purpureum4--,some long1 moderately thin internodes made four revolutions at an average rate of #c hrs4 #ae m4 ,the course pursued was very irregular1 namely1 an extremely narrow ellipse1 a large circle1 an irregular spire or a zigzag line1 and sometimes the apex stood still4 ,the young petioles1 when brought by the revolving movement into contact with sticks1 clasped them1 and soon increased considerably in thickness4 ,but they are not quite so sensitive to a weight as those of the ,rhodochiton1 for loops of thread weighing one-eighth of a grain did not always cause them to bend4 ,this plant presents a case not observed by me in any other leaf-climber or twiner1 #ga namely1 that the young internodes of the stem are sensitive to a touch4 ,when a petiole of this species clasps a stick1 it draws the base of the internode against it2 and then the internode itself bends towards the stick1 which is caught between the stem and the petiole as by a pair of pincers4 ,the internode afterwards straightens itself1 excepting the part in actual contact with the stick4 ,young internodes alone are sensitive1 and these are sensitive on all sides along their whole length4 ,i made fifteen trials by twice or thrice lightly rubbing with a thin twig several internodes2 and in about #b hrs41 but in one case in #c hrs41 all were bent3 they became straight again in about #d hrs4 afterwards4 ,an internode1 which was rubbed as often as six or seven times1 became just perceptibly curved in #a hr4 #ae m41 and in #c hrs4 the curvature increased much2 it became straight again in the course of the succeeding night4 ,i rubbed some internodes one day on one side1 and the next day either on the opposite side or at right angles to the first side2 and the curvature was always towards the rubbed side4 ,according to ,palm 7p4 #fc71 the petioles of ,linaria cirrhosa and1 to a limited degree1 those of ,l4 elatine have the power of clasping a support4 ,,solanace4--,solanum jasminoides4--,some of the species in this large genus are twiners2 but the present species is a true leaf-climber4 ,a long1 nearly upright shoot made four revolutions1 moving against the sun1 very regularly at an average rate of #c hrs4 #bf m4 ,the shoots1 however1 sometimes stood still4 ,it is considered a greenhouse plant2 but when kept there1 the petioles took several days to clasp a stick3 in the hothouse a stick was clasped in #g hrs4 ,in the greenhouse a petiole was not affected by a loop of string1 suspended during several days and weighing #b grains 7#afc mg472 but in the hothouse one was made to curve by a loop weighing #a4fd gr4 7#ajf4bg mg472 and1 on the removal of the string1 it became straight again4 ,another petiole was not at all acted on by a loop weighing only #j4hb of a grain 7#ec4ad mg47 ,we have seen that the petioles of some other leaf-climbing plants are affected by one-thirteenth of this latter weight4 ,in this species1 and in no other leaf-climber seen by me1 a full-grown leaf is capable of clasping a stick2 but in the greenhouse the movement was so extraordinarily slow that the act required several weeks2 on each succeeding week it was clear that the petiole had become more and more curved1 until at last it firmly clasped the stick4 ,picture3 ,fig4 #c4 ,solanum jasminoides1 with one of its petioles clasping a stick ,the flexible petiole of a half or a quarter grown leaf which has clasped an object for three or four days increases much in thickness1 and after several weeks becomes so wonderfully hard and rigid that it can hardly be removed from its support4 ,on comparing a thin transverse slice of such a petiole with one from an older leaf growing close beneath1 which had not clasped anything1 its diameter was found to be fully doubled1 and its structure greatly changed4 ,in two other petioles similarly compared1 and here represented1 the increase in diameter was not quite so great4 ,in the section of the petiole in its ordinary state 7,a71 we see a semilunar band of cellular tissue 7not well shown in the woodcut7 differing slightly in appearance from that outside it1 and including three closely approximate groups of dark vessels4 ,near the upper surface of the petiole1 beneath two exterior ridges1 there are two other small circular groups of vessels4 ,in the section of the petiole 7,b7 which had clasped during several weeks a stick1 the two exterior ridges have become much less prominent1 and the two groups of woody vessels beneath them much increased in diameter4 ,the semilunar band has been converted into a complete ring of very hard1 white1 woody tissue1 with lines radiating from the centre4 ,the three groups of vessels1 which1 though near together1 were before distinct1 are now completely blended4 ,the upper part of this ring of woody vessels1 formed by the prolongation of the horns of the original semilunar band1 is narrower than the lower part1 and slightly less compact4 ,this petiole after clasping the stick had actually become thicker than the stem from which it arose2 and this was chiefly due to the increased thickness of the ring of wood4 ,this ring presented1 both in a transverse and longitudinal section1 a closely similar structure to that of the stem4 ,it is a singular morphological fact that the petiole should thus acquire a structure almost identically the same with that of the axis2 and it is a still more singular physiological fact that so great a change should have been induced by the mere act of clasping a support4 #ge ,picture3 ,fig4 #d4 ,solanum jasminoides4 ,a4 ,section of the petiole in its ordinary state4 ,b4 ,section of the petiole some weeks after it had clasped a stick1 as shown in fig4 #b ,,fumariace4--,fumaria officinalis4--,it could not have been anticipated that so lowly a plant as this ,fumaria should have been a climber4 ,it climbs by the aid of the main and lateral petioles of its compound leaves2 and even the much-flattened terminal portion of the petiole can seize a support4 ,i have seen a substance as soft as a withered blade of grass caught4 ,petioles which have clasped any object ultimately become rather thicker and more cylindrical4 ,on lightly rubbing several petioles with a twig1 they became perceptibly curved in #a hr4 #ae m41 and subsequently straightened themselves4 ,a stick gently placed in the angle between two sub-petioles excited them to move1 and was almost clasped in #i hrs4 ,a loop of thread1 weighing one-eighth of a grain1 caused1 after #ab hrs4 and before #bj hrs1 had elapsed1 a considerable curvature2 but it was never fairly clasped by the petiole4 ,the young internodes are in continual movement1 which is considerable in extent1 but very irregular2 a zigzag line1 or a spire crossing itself2 or a figure of #h being formed4 ,the course during #ab hrs41 when traced on a bell-glass1 apparently represented about four ellipses4 ,the leaves themselves likewise move spontaneously1 the main petioles curving themselves in accordance with the movements of the internodes2 so that when the latter moved to one side1 the petioles moved to the same side1 then1 becoming straight1 reversed their curvature4 ,the petioles1 however1 do not move over a wide space1 as could be seen when a shoot was securely tied to a stick4 ,the leaf in this case followed an irregular course1 like that made by the internodes4 ,adlumia cirrhosa4--,i raised some plants late in the summer2 they formed very fine leaves1 but threw up no central stem4 ,the first-formed leaves were not sensitive2 some of the later ones were so1 but only towards their extremities1 which were thus enabled to clasp sticks4 ,this could be of no service to the plant1 as these leaves rose from the ground2 but it showed what the future character of the plant would have been1 had it grown tall enough to climb4 ,the tip of one of these basal leaves1 whilst young1 described in #a hr4 #cf m4 a narrow ellipse1 open at one end1 and exactly three inches in length2 a second ellipse was broader1 more irregular1 and shorter1 viz41 only #b inches in length1 and was completed in #b hrs4 #b m4 ,from the analogy of ,fumaria and ,corydalis1 ,i have no doubt that the internodes of ,adlumia have the power of revolving4 ,corydalis claviculata4--,this plant is interesting from being in a condition so exactly intermediate between a leaf-climber and a tendril-bearer1 that it might have been described under either head2 but1 for reasons hereafter assigned1 it has been classed amongst tendril-bearers4 ,besides the plants already described1 ,bignonia unguis and its close allies1 though aided by tendrils1 have clasping petioles4 ,according to ,mohl 7p4 #dj71 ,cocculus ,japonicus 7one of the ,menispermace7 and a fern1 the ,ophioglossum ,japonicum 7p4 #ci71 climb by their leaf-stalks4 99 99 99 99 99 ,we now come to a small section of plants which climb by means of the produced midribs or tips of their leaves4 ,,liliace4--,gloriosa ,plantii4--,the stem of a half-grown plant continually moved1 generally describing an irregular spire1 but sometimes oval figures with the longer axes directed in different lines4 ,it either followed the sun1 or moved in an opposite course1 and sometimes stood still before reversing its direction4 ,one oval was completed in #c hrs4 #dj m42 of two horseshoe-shaped figures1 one was completed in #d hrs4 #ce m4 and the other in #c hrs4 ,the shoots1 in their movements1 reached points between four and five inches asunder4 ,the young leaves1 when first developed1 stand up nearly vertically2 but by the growth of the axis1 and by the spontaneous bending down of the terminal half of the leaf1 they soon become much inclined1 and ultimately horizontal4 ,the end of the leaf forms a narrow1 ribbon-like1 thickened projection1 which at first is nearly straight1 but by the time the leaf gets into an inclined position1 the end bends downwards into a well-formed hook4 ,this hook is now strong and rigid enough to catch any object1 and1 when caught1 to anchor the plant and stop the revolving movement4 ,its inner surface is sensitive1 but not in nearly so high a degree as that of the many before-described petioles2 for a loop of string1 weighing #a4fd grain1 produced no effect4 ,when the hook has caught a thin twig or even a rigid fibre1 the point may be perceived in from #a hr4 to #c hrs4 to have curled a little inwards2 and1 under favourable circumstances1 it curls round and permanently seizes an object in from #h hrs4 to #aj hrs4 ,the hook when first formed1 before the leaf has bent downwards1 is but little sensitive4 ,if it catches hold of nothing1 it remains open and sensitive for a long time2 ultimately the extremity spontaneously and slowly curls inwards1 and makes a button-like1 flat1 spiral coil at the end of the leaf4 ,one leaf was watched1 and the hook remained open for thirty-three days2 but during the last week the tip had curled so much inwards that only a very thin twig could have been inserted within it4 ,as soon as the tip has curled so much inwards that the hook is converted into a ring1 its sensibility is lost2 but as long as it remains open some sensibility is retained4 ,whilst the plant was only about six inches in height1 the leaves1 four or five in number1 were broader than those subsequently produced2 their soft and but little-attenuated tips were not sensitive1 and did not form hooks2 nor did the stem then revolve4 ,at this early period of growth1 the plant can support itself2 its climbing powers are not required1 and consequently are not developed4 ,so again1 the leaves on the summit of a full-grown flowering plant1 which would not require to climb any higher1 were not sensitive and could not clasp a stick4 ,we thus see how perfect is the economy of nature4 ,,commelynace4--,flagellaria ,indica4--,from dried specimens it is manifest that this plant climbs exactly like the ,gloriosa4 ,a young plant #ab inches in height1 and bearing fifteen leaves1 had not a single leaf as yet produced into a hook or tendril-like filament2 nor did the stem revolve4 ,hence this plant acquires its climbing powers later in life than does the ,gloriosa lily4 ,according to ,mohl 7p4 #da71 ,uvularia 7,melanthace7 also climbs like ,gloriosa4 ,these three last-named genera are ,monocotyledons2 but there is one ,dicotyledon1 namely ,nepenthes1 which is ranked by ,mohl 7p4 #da7 amongst tendril-bearers2 and ,i hear from ,dr4 ,hooker that most of the species climb well at ,kew4 ,this is effected by the stalk or midrib between the leaf and the pitcher coiling round any support4 ,the twisted part becomes thicker2 but ,i observed in ,mr4 ,veitch's hothouse that the stalk often takes a turn when not in contact with any object1 and that this twisted part is likewise thickened4 ,two vigorous young plants of ,n4 lvis and ,n4 distillatoria1 in my hothouse1 whilst less than a foot in height1 showed no sensitiveness in their leaves1 and had no power of climbing4 ,but when ,n4 lvis had grown to a height of #af inches1 there were signs of these powers4 ,the young leaves when first formed stand upright1 but soon become inclined2 at this period they terminate in a stalk or filament1 with the pitcher at the extremity hardly at all developed4 ,the leaves now exhibited slight spontaneous movements2 and when the terminal filaments came into contact with a stick1 they slowly bent round and firmly seized it4 ,but owing to the subsequent growth of the leaf1 this filament became after a time quite slack1 though still remaining firmly coiled round the stick4 ,hence it would appear that the chief use of the coiling1 at least whilst the plant is young1 is to support the pitcher with its load of secreted fluid4 99 99 99 99 99 ,summary on ,leaf-climbers4--,plants belonging to eight families are known to have clasping petioles1 and plants belonging to four families climb by the tips of their leaves4 ,in all the species observed by me1 with one exception1 the young internodes revolve more or less regularly1 in some cases as regularly as those of a twining plant4 ,they revolve at various rates1 in most cases rather rapidly4 ,some few can ascend by spirally twining round a support4 ,differently from most twiners1 there is a strong tendency in the same shoot to revolve first in one and then in an opposite direction4 ,the object gained by the revolving movement is to bring the petioles or the tips of the leaves into contact with surrounding objects2 and without this aid the plant would be much less successful in climbing4 ,with rare exceptions1 the petioles are sensitive only whilst young4 ,they are sensitive on all sides1 but in different degrees in different plants2 and in some species of ,clematis the several parts of the same petiole differ much in sensitiveness4 ,the hooked tips of the leaves of the ,gloriosa are sensitive only on their inner or inferior surfaces4 ,the petioles are sensitive to a touch and to excessively slight continued pressure1 even from a loop of soft thread weighing only the one-sixteenth of a grain 7#d4je mg472 and there is reason to believe that the rather thick and stiff petioles of ,clematis flammula are sensitive to even much less weight if spread over a wide surface4 ,the petioles always bend towards the side which is pressed or touched1 at different rates in different species1 sometimes within a few minutes1 but generally after a much longer period4 ,after temporary contact with any object1 the petiole continues to bend for a considerable time2 afterwards it slowly becomes straight again1 and can then re-act4 ,a petiole excited by an extremely slight weight sometimes bends a little1 and then becomes accustomed to the stimulus1 and either bends no more or becomes straight again1 the weight still remaining suspended4 ,petioles which have clasped an object for some little time cannot recover their original position4 ,after remaining clasped for two or three days1 they generally increase much in thickness either throughout their whole diameter or on one side alone2 they subsequently become stronger and more woody1 sometimes to a wonderful degree2 and in some cases they acquire an internal structure like that of the stem or axis4 ,the young internodes of the ,lophospermum as well as the petioles are sensitive to a touch1 and by their combined movement seize an object4 ,the flower-peduncles of the ,maurandia semperflorens revolve spontaneously and are sensitive to a touch1 yet are not used for climbing4 ,the leaves of at least two1 and probably of most1 of the species of ,clematis1 of ,fumaria and ,adlumia1 spontaneously curve from side to side1 like the internodes1 and are thus better adapted to seize distant objects4 ,the petioles of the perfect leaves of ,tropolum tricolorum1 as well as the tendril-like filaments of the plants whilst young1 ultimately move towards the stem or the supporting stick1 which they then clasp4 ,these petioles and filaments also show some tendency to contract spirally4 ,the tips of the uncaught leaves of the ,gloriosa1 as they grow old1 contract into a flat spire or helix4 ,these several facts are interesting in relation to true tendrils4 ,with leaf climbers1 as with twining plants1 the first internodes which rise from the ground do not1 at least in the cases observed by me1 spontaneously revolve2 nor are the petioles or tips of the first-formed leaves sensitive4 ,in certain species of ,clematis1 the large size of the leaves1 together with their habit of revolving1 and the extreme sensitiveness of their petioles1 appear to render the revolving movement of the internodes superfluous2 and this latter power has consequently become much enfeebled4 ,in certain species of ,tropolum1 both the spontaneous movements of the internodes and the sensitiveness of the petioles have become much enfeebled1 and in one species have been completely lost4 ,,chapter ,,iii4 ,,tendril-,,bearers4 ,nature of tendrils--,,bignoniace1 various species of1 and their different modes of climbing--,tendrils which avoid the light and creep into crevices--,development of adhesive discs--,excellent adaptations for seizing different kinds of supports4--,,polemoniace--,coba scandens much branched and hooked tendrils1 their manner of action--,,leguminos--,,composit--,,smila ce--,smilax aspera1 its inefficient tendrils--,,fumariace--,corydalis claviculata1 its state intermediate between that of a leaf-climber and a tendril-bearer4 ,,by tendrils ,i mean filamentary organs1 sensitive to contact and used exclusively for climbing4 ,by this definition1 spines1 hooks and rootlets1 all of which are used for climbing1 are excluded4 ,true tendrils are formed by the modification of leaves with their petioles1 of flower-peduncles1 branches1 #hd and perhaps stipules4 ,mohl1 who includes under the name of tendrils various organs having a similar external appearance1 classes them according to their homological nature1 as being modified leaves1 flower-peduncles1 c4 ,this would be an excellent scheme2 but ,i observe that botanists are by no means unanimous on the homological nature of certain tendrils4 ,consequently ,i will describe tendril-bearing plants by natural families1 following ,lindley's classification2 and this will in most cases keep those of the same nature together4 ,the species to be described belong to ten families1 and will be given in the following order3--,bignoniace1 ,polemoniace1 ,leguminos1 ,composit1 ,smilace1 ,fumariace1 ,cucurbitace1 ,vitace1 ,sapindace1 ,passiflorace4 #he ,,bignoniace4--,this family contains many tendril-bearers1 some twiners1 and some root-climbers4 ,the tendrils always consist of modified leaves4 ,nine species of ,bignonia1 selected by hazard1 are here described1 in order to show what diversity of structure and action there may be within the same genus1 and to show what remarkable powers some tendrils possess4 ,the species1 taken together1 afford connecting links between twiners1 leaf-climbers1 tendril-bearers1 and root-climbers4 ,picture3 ,fig4 #e4 ,bignonia4 ,unnamed species from ,kew ,bignonia 7an unnamed species from ,kew1 closely allied to ,b4 unguis1 but with smaller and rather broader leaves74--,a young shoot from a cut-down plant made three revolutions against the sun1 at an average rate of #b hrs4 #f m4 ,the stem is thin and flexible2 it twined round a slender vertical stick1 ascending from left to right1 as perfectly and as regularly as any true twining-plant4 ,when thus ascending1 it makes no use of its tendrils or petioles2 but when it twined round a rather thick stick1 and its petioles were brought into contact with it1 these curved round the stick1 showing that they have some degree of irritability4 ,the petioles also exhibit a slight degree of spontaneous movement2 for in one case they certainly described minute1 irregular1 vertical ellipses4 ,the tendrils apparently curve themselves spontaneously to the same side with the petioles2 but from various causes1 it was difficult to observe the movement of either the tendrils or petioles1 in this and the two following species4 ,the tendrils are so closely similar in all respects to those of ,b4 unguis1 that one description will suffice4 ,bignonia unguis4--,the young shoots revolve1 but less regularly and less quickly than those of the last species4 ,the stem twines imperfectly round a vertical stick1 sometimes reversing its direction1 in the same manner as described in so many leaf-climbers2 and this plant though possessing tendrils1 climbs to a certain extent like a leaf-climber4 ,each leaf consists of a petiole bearing a pair of leaflets1 and terminates in a tendril1 which is formed by the modification of three leaflets1 and closely resembles that above figured 7fig4 #e74 ,but it is a little larger1 and in a young plant was about half an inch in length4 ,it is curiously like the leg and foot of a small bird1 with the hind toe cut off4 ,the straight leg or tarsus is longer than the three toes1 which are of equal length1 and diverging1 lie in the same plane4 ,the toes terminate in sharp1 hard claws1 much curved downwards1 like those on a bird's foot4 ,the petiole of the leaf is sensitive to contact2 even a small loop of thread suspended for two days caused it to bend upwards2 but the sub-petioles of the two lateral leaflets are not sensitive4 ,the whole tendril1 namely1 the tarsus and the three toes1 are likewise sensitive to contact1 especially on their under surfaces4 ,when a shoot grows in the midst of thin branches1 the tendrils are soon brought by the revolving movement of the internodes into contact with them2 and then one toe of the tendril or more1 commonly all three1 bend1 and after several hours seize fast hold of the twigs1 like a bird when perched4 ,if the tarsus of the tendril comes into contact with a twig1 it goes on slowly bending1 until the whole foot is carried quite round1 and the toes pass on each side of the tarsus and seize it4 ,in like manner1 if the petiole comes into contact with a twig1 it bends round1 carrying the tendril1 which then seizes its own petiole or that of the opposite leaf4 ,the petioles move spontaneously1 and thus1 when a shoot attempts to twine round an upright stick1 those on both sides after a time come into contact with it1 and are excited to bend4 ,ultimately the two petioles clasp the stick in opposite directions1 and the foot-like tendrils1 seizing on each other or on their own petioles1 fasten the stem to the support with surprising security4 ,the tendrils are thus brought into action1 if the stem twines round a thin vertical stick2 and in this respect the present species differs from the last4 ,both species use their tendrils in the same manner when passing through a thicket4 ,this plant is one of the most efficient climbers which ,i have observed2 and it probably could ascend a polished stem incessantly tossed by heavy storms4 ,to show how important vigorous health is for the action of all the parts1 ,i may mention that when ,i first examined a plant which was growing moderately well1 though not vigorously1 ,i concluded that the tendrils acted only like the hooks on a bramble1 and that it was the most feeble and inefficient of all climbers6 ,bignonia ,tweedyana4--,this species is closely allied to the last1 and behaves in the same manner2 but perhaps twines rather better round a vertical stick4 ,on the same plant1 one branch twined in one direction and another in an opposite direction4 ,the internodes in one case made two circles1 each in #b hrs4 #cc m4 ,i was enabled to observe the spontaneous movements of the petioles better in this than in the two preceding species3 one petiole described three small vertical ellipses in the course of #aa hrs41 whilst another moved in an irregular spire4 ,some little time after a stem has twined round an upright stick1 and is securely fastened to it by the clasping petioles and tendrils1 it emits arial roots from the bases of its leaves2 and these roots curve partly round and adhere to the stick4 ,this species of ,bignonia1 therefore1 combines four different methods of climbing generally characteristic of distinct plants1 namely1 twining1 leaf-climbing1 tendril-climbing1 and root-climbing4 ,in the three foregoing species1 when the foot-like tendril has caught an object1 it continues to grow and thicken1 and ultimately becomes wonderfully strong1 in the same manner as the petioles of leaf-climbers4 ,if the tendril catches nothing1 it first slowly bends downwards1 and then its power of clasping is lost4 ,very soon afterwards it disarticulates itself from the petiole1 and drops off like a leaf in autumn4 ,i have seen this process of disarticulation in no other tendrils1 for these1 when they fail to catch an object1 merely wither away4 ,bignonia venusta4--,the tendrils differ considerably from those of the previous species4 ,the lower part1 or tarsus1 is four times as long as the three toes2 these are of equal length and diverge equally1 but do not lie in the same plane2 their tips are bluntly hooked1 and the whole tendril makes an excellent grapnel4 ,the tarsus is sensitive on all sides2 but the three toes are sensitive only on their outer surfaces4 ,the sensitiveness is not much developed2 for a slight rubbing with a twig did not cause the tarsus or the toes to become curved until an hour had elapsed1 and then only in a slight degree4 ,subsequently they straightened themselves4 ,both the tarsus and toes can seize well hold of sticks4 ,if the stem is secured1 the tendrils are seen spontaneously to sweep large ellipses2 the two opposite tendrils moving independently of one another4 ,i have no doubt1 from the analogy of the two following allied species1 that the petioles also move spontaneously2 but they are not irritable like those of ,b4 unguis and ,b4 ,tweedyana4 ,the young internodes sweep large circles1 one being completed in #b hrs4 #ae m41 and a second in #b hrs4 #ee m4 ,by these combined movements of the internodes1 petioles1 and grapnel-like tendrils1 the latter are soon brought into contact with surrounding objects4 ,when a shoot stands near an upright stick1 it twines regularly and spirally round it4 ,as it ascends1 it seizes the stick with one of its tendrils1 and1 if the stick be thin1 the right--and left-hand tendrils are alternately used4 ,this alternation follows from the stem necessarily taking one twist round its own axis for each completed circle4 ,the tendrils contract spirally a short time after catching any object2 those which catch nothing merely bend slowly downwards4 ,but the whole subject of the spiral contraction of tendrils will be discussed after all the tendril-bearing species have been described4 ,bignonia littoralis4--,the young internodes revolve in large ellipses4 ,an internode bearing immature tendrils made two revolutions1 each in #c hrs4 #ej m42 but when grown older with the tendrils mature1 it made two ellipses1 each at the rate of #b hrs4 #dd m4 ,this species1 unlike the preceding1 is incapable of twining round a stick3 this does not appear to be due to any want of flexibility in the internodes or to the action of the tendrils1 and certainly not to any want of the revolving power2 nor can ,i account for the fact4 ,nevertheless the plant readily ascends a thin upright stick by seizing a point above with its two opposite tendrils1 which then contract spirally4 ,if the tendrils seize nothing1 they do not become spiral4 ,the species last described1 ascended a vertical stick by twining spirally and by seizing it alternately with its opposite tendrils1 like a sailor pulling himself up a rope1 hand over hand2 the present species pulls itself up1 like a sailor seizing with both hands together a rope above his head4 ,the tendrils are similar in structure to those of the last species4 ,they continue growing for some time1 even after they have clasped an object4 ,when fully grown1 though borne by a young plant1 they are #i inches in length4 ,the three divergent toes are shorter relatively to the tarsus than in the former species2 they are blunt at their tips and but slightly hooked2 they are not quite equal in length1 the middle one being rather longer than the others4 ,their outer surfaces are highly sensitive2 for when lightly rubbed with a twig1 they became perceptibly curved in #d m4 and greatly curved in #g m4 ,in #g hrs4 they became straight again and were ready to re-act4 ,the tarsus1 for the space of one inch close to the toes1 is sensitive1 but in a rather less degree than the toes2 for the latter after a slight rubbing1 became curved in about half the time4 ,even the middle part of the tarsus is sensitive to prolonged contact1 as soon as the tendril has arrived at maturity4 ,after it has grown old1 the sensitiveness is confined to the toes1 and these are only able to curl very slowly round a stick4 ,a tendril is perfectly ready to act1 as soon as the three toes have diverged1 and at this period their outer surfaces first become irritable4 ,the irritability spreads but little from one part when excited to another3 thus1 when a stick was caught by the part immediately beneath the three toes1 these seldom clasped it1 but remained sticking straight out4 ,the tendrils revolve spontaneously4 ,the movement begins before the tendril is converted into a three-pronged grapnel by the divergence of the toes1 and before any part has become sensitive2 so that the revolving movement is useless at this early period4 ,the movement is1 also1 now slow1 two ellipses being completed conjointly in #bd hrs4 #ah m4 ,a mature tendril made an ellipse in #f hrs42 so that it moved much more slowly than the internodes4 ,the ellipses which were swept1 both in a vertical and horizontal plane1 were of large size4 ,the petioles are not in the least sensitive1 but revolve like the tendrils4 ,we thus see that the young internodes1 the petioles1 and the tendrils all continue revolving together1 but at different rates4 ,the movements of the tendrils which rise opposite one another are quite independent4 ,hence1 when the whole shoot is allowed freely to revolve1 nothing can be more intricate than the course followed by the extremity of each tendril4 ,a wide space is thus irregularly searched for some object to be grasped4 ,one other curious point remains to be mentioned4 ,in the course of a few days after the toes have closely clasped a stick1 their blunt extremities become developed1 though not invariably1 into irregular disc-like balls which have the power of adhering firmly to the wood4 ,as similar cellular outgrowths will be fully described under ,b4 capreolata1 ,i will here say nothing more about them4 ,bignonia quinoctialis1 var4 ,chamberlaynii4--,the internodes1 the elongated non-sensitive petioles1 and the tendrils all revolve4 ,the stem does not twine1 but ascends a vertical stick in the same manner as the last species4 ,the tendrils also resemble those of the last species1 but are shorter2 the three toes are more unequal in length1 the two outer ones being about one-third shorter and rather thinner than the middle toe2 but they vary in this respect4 ,they terminate in small hard points2 and what is important1 cellular adhesive discs are not developed4 ,the reduced size of two of the toes as well as their lessened sensitiveness1 seem to indicate a tendency to abortion2 and on one of my plants the first-formed tendrils were sometimes simple1 that is1 were not divided into three toes4 ,we are thus naturally led to the three following species with undivided tendrils3-- ,bignonia speciosa4--,the young shoots revolve irregularly1 making narrow ellipses1 spires or circles1 at rates varying from #c hrs4 #cj m4 to #d hrs4 #dj m42 but they show no tendency to twine4 ,whilst the plant is young and does not require a support1 tendrils are not developed4 ,those borne by a moderately young plant were five inches in length4 ,they revolve spontaneously1 as do the short and non-sensitive petioles4 ,when rubbed1 they slowly bend to the rubbed side and subsequently straighten themselves2 but they are not highly sensitive4 ,there is something strange in their behaviour3 ,i repeatedly placed close to them1 thick and thin1 rough and smooth sticks and posts1 as well as string suspended vertically1 but none of these objects were well seized4 ,after clasping an upright stick1 they repeatedly loosed it again1 and often would not seize it at all1 or their extremities did not coil closely round4 ,i have observed hundreds of tendrils belonging to various ,cucurbitaceous1 ,passifloraceous1 and ,leguminous plants1 and never saw one behave in this manner4 ,when1 however1 my plant had grown to a height of eight or nine feet1 the tendrils acted much better4 ,they now seized a thin1 upright stick horizontally1 that is1 at a point on their own level1 and not some way up the stick as in the case of all the previous species4 ,nevertheless1 the non-twining stem was enabled by this means to ascend the stick4 ,the extremity of the tendril is almost straight and sharp4 ,the whole terminal portion exhibits a singular habit1 which in an animal would be called an instinct2 for it continually searches for any little crevice or hole into which to insert itself4 ,i had two young plants2 and1 after having observed this habit1 ,i placed near them posts1 which had been bored by beetles1 or had become fissured by drying4 ,the tendrils1 by their own movement and by that of the internodes1 slowly travelled over the surface of the wood1 and when the apex came to a hole or fissure it inserted itself2 in order to effect this the extremity for a length of half or quarter of an inch1 would often bend itself at right angles to the basal part4 ,i have watched this process between twenty and thirty times4 ,the same tendril would frequently withdraw from one hole and insert its point into a second hole4 ,i have also seen a tendril keep its point1 in one case for #bj hrs4 and in another for #cf hrs41 in a minute hole1 and then withdraw it4 ,whilst the point is thus temporarily inserted1 the opposite tendril goes on revolving4 ,the whole length of a tendril often fits itself closely to any surface of wood with which it has come into contact2 and ,i have observed one bent at right angles1 from having entered a wide and deep fissure1 with its apex abruptly re-bent and inserted into a minute lateral hole4 ,after a tendril has clasped a stick1 it contracts spirally2 if it remains unattached it hangs straight downwards4 ,if it has merely adapted itself to the inequalities of a thick post1 though it has clasped nothing1 or if it has inserted its apex into some little fissure1 this stimulus suffices to induce spiral contraction2 but the contraction always draws the tendril away from the post4 ,so that in every case these movements1 which seem so nicely adapted for some purpose1 were useless4 ,on one occasion1 however1 the tip became permanently jammed into a narrow fissure4 ,i fully expected1 from the analogy of ,b4 capreolata and ,b4 littoralis1 that the tips would have been developed into adhesive discs2 but ,i could never detect even a trace of this process4 ,there is therefore at present something unintelligible about the habits of this plant4 ,bignonia picta4--,this species closely resembles the last in the structure and movements of its tendrils4 ,i also casually examined a fine growing plant of the allied ,b4 ,lindleyi1 and this apparently behaved in all respects in the same manner4 ,bignonia capreolata4--,we now come to a species having tendrils of a different type2 but first for the internodes4 ,a young shoot made three large revolutions1 following the sun1 at an average rate of #b hrs4 #bc m4 ,the stem is thin and flexible1 and ,i have seen one make four regular spiral turns round a thin upright stick1 ascending of course from right to left1 and therefore in a reversed direction compared with the before described species4 ,afterwards1 from the interference of the tendrils1 it ascended either straight up the stick or in an irregular spire4 ,the tendrils are in some respects highly remarkable4 ,in a young plant they were about #b inches in length and much branched1 the five chief branches apparently representing two pairs of leaflets and a terminal one4 ,each branch is1 however1 bifid or more commonly trifid towards the extremity1 with the points blunt yet distinctly hooked4 ,a tendril bends to any side which is lightly rubbed1 and subsequently becomes straight again2 but a loop of thread weighing th of a grain produced no effect4 ,on two occasions the terminal branches became slightly curved in #aj m4 after they had touched a stick2 and in #cj m4 the tips were curled quite round it4 ,the basal part is less sensitive4 ,the tendrils revolved in an apparently capricious manner1 sometimes very slightly or not at all2 at other times they described large regular ellipses4 ,i could detect no spontaneous movement in the petioles of the leaves4 ,whilst the tendrils are revolving more or less regularly1 another remarkable movement takes place1 namely1 a slow inclination from the light towards the darkest side of the house4 ,i repeatedly changed the position of my plants1 and some little time after the revolving movement had ceased1 the successively formed tendrils always ended by pointing to the darkest side4 ,when ,i placed a thick post near a tendril1 between it and the light1 the tendril pointed in that direction4 ,in two instances a pair of leaves stood so that one of the two tendrils was directed towards the light and the other to the darkest side of the house2 the latter did not move1 but the opposite one bent itself first upwards and then right over its fellow1 so that the two became parallel1 one above the other1 both pointing to the dark3 ,i then turned the plant half round2 and the tendril which had turned over recovered its original position1 and the opposite one which had not before moved1 now turned over to the dark side4 ,lastly1 on another plant1 three pairs of tendrils were produced at the same time by three shoots1 and all happened to be differently directed3 ,i placed the pot in a box open only on one side1 and obliquely facing the light2 in two days all six tendrils pointed with unerring truth to the darkest corner of the box1 though to do this each had to bend in a different manner4 ,six wind-vanes could not have more truly shown the direction of the wind1 than did these branched tendrils the course of the stream of light which entered the box4 ,i left these tendrils undisturbed for above #bd hrs41 and then turned the pot half round2 but they had now lost their power of movement1 and could not any longer avoid the light4 ,when a tendril has not succeeded in clasping a support1 either through its own revolving movement or that of the shoot1 or by turning towards any object which intercepts the light1 it bends vertically downwards and then towards its own stem1 which it seizes together with the supporting stick1 if there be one4 ,a little aid is thus given in keeping the stem secure4 ,if the tendril seizes nothing1 it does not contract spirally1 but soon withers away and drops off4 ,if it seizes an object1 all the branches contract spirally4 ,i have stated that after a tendril has come into contact with a stick1 it bends round it in about half an hour2 but ,i repeatedly observed1 as in the case of ,b4 speciosa and its allies1 that it often again loosed the stick2 sometimes seizing and loosing the same stick three or four times4 ,knowing that the tendrils avoided the light1 ,i gave them a glass tube blackened within1 and a well-blackened zinc plate3 the branches curled round the tube and abruptly bent themselves round the edges of the zinc plate2 but they soon recoiled from these objects with what ,i can only call disgust1 and straightened themselves4 ,i then placed a post with extremely rugged bark close to a pair of tendrils2 twice they touched it for an hour or two1 and twice they withdrew2 at last one of the hooked extremities curled round and firmly seized an excessively minute projecting point of bark1 and then the other branches spread themselves out1 following with accuracy every inequality of the surface4 ,i afterwards placed near the plant a post without bark but much fissured1 and the points of the tendrils crawled into all the crevices in a beautiful manner4 ,to my surprise1 ,i observed that the tips of the immature tendrils1 with the branches not yet fully separated1 likewise crawled just like roots into the minutest crevices4 ,in two or three days after the tips had thus crawled into the crevices1 or after their hooked ends had seized minute points1 the final process1 now to be described1 commenced4 ,this process ,i discovered by having accidentally left a piece of wool near a tendril2 and this led me to bind a quantity of flax1 moss1 and wool loosely round sticks1 and to place them near tendrils4 ,the wool must not be dyed1 for these tendrils are excessively sensitive to some poisons4 ,the hooked points soon caught hold of the fibres1 even loosely floating fibres1 and now there was no recoiling2 on the contrary1 the excitement caused the hooks to penetrate the fibrous mass and to curl inwards1 so that each hook caught firmly one or two fibres1 or a small bundle of them4 ,the tips and the inner surfaces of the hooks now began to swell1 and in two or three days were visibly enlarged4 ,after a few more days the hooks were converted into whitish1 irregular balls1 rather above the #j4jeth of an inch 7#a4bg mm47 in diameter1 formed of coarse cellular tissue1 which sometimes wholly enveloped and concealed the hooks themselves4 ,the surfaces of these balls secrete some viscid resinous matter1 to which the fibres of the flax1 c41 adhere4 ,when a fibre has become fastened to the surface1 the cellular tissue does not grow directly beneath it1 but continues to grow closely on each side2 so that when several adjoining fibres1 though excessively thin1 were caught1 so many crests of cellular matter1 each not as thick as a human hair1 grew up between them1 and these1 arching over on both sides1 adhered firmly together4 ,as the whole surface of the ball continues to grow1 fresh fibres adhere and are afterwards enveloped2 so that ,i have seen a little ball with between fifty and sixty fibres of flax crossing it at various angles and all embedded more or less deeply4 ,every gradation in the process could be followed--some fibres merely sticking to the surface1 others lying in more or less deep furrows1 or deeply embedded1 or passing through the very centre of the cellular ball4 ,the embedded fibres are so closely clasped that they cannot be withdrawn4 ,the outgrowing tissue has so strong a tendency to unite1 that two balls produced by distinct tendrils sometimes unite and grow into a single one4 ,on one occasion1 when a tendril had curled round a stick1 half an inch in diameter1 an adhesive disc was formed2 but this does not generally occur in the case of smooth sticks or posts4 ,if1 however1 the tip catches a minute projecting point1 the other branches form discs1 especially if they find crevices to crawl into4 ,the tendrils failed to attach themselves to a brick wall4 ,i infer from the adherence of the fibres to the discs or balls1 that these secrete some resinous adhesive matter2 and more especially from such fibres becoming loose if immersed in sulphuric ether4 ,this fluid likewise removes small1 brown1 glistening points which can generally be seen on the surfaces of the older discs4 ,if the hooked extremities of the tendrils do not touch anything1 discs1 as far as ,i have seen1 are never formed2 #ajb but temporary contact during a moderate time suffices to cause their development4 ,i have seen eight discs formed on the same tendril4 ,after their development the tendrils contract spirally1 and become woody and very strong4 ,a tendril in this state supported nearly seven ounces1 and would apparently have supported a considerably greater weight1 had not the fibres of flax to which the discs were attached yielded4 ,from the facts now given1 we may infer that though the tendrils of this ,bignonia can occasionally adhere to smooth cylindrical sticks and often to rugged bark1 yet that they are specially adapted to climb trees clothed with lichens1 mosses1 or other such productions2 and ,i hear from ,professor ,asa ,gray that the ,polypodium incanum abounds on the forest-trees in the districts of ,north ,america where this species of ,bignonia grows4 ,finally1 ,i may remark how singular a fact it is that a leaf should be metamorphosed into a branched organ which turns from the light1 and which can by its extremities either crawl like roots into crevices1 or seize hold of minute projecting points1 these extremities afterwards forming cellular outgrowths which secrete an adhesive cement1 and then envelop by their continued growth the finest fibres4 ,eccremocarpus scaber 7,bignoniace74--,plants1 though growing pretty well in my green-house1 showed no spontaneous movements in their shoots or tendrils2 but when removed to the hot-house1 the young internodes revolved at rates varying from #c hrs4 #ae m4 to #a hr4 #ac m4 ,one large circle was swept at this latter unusually quick rate2 but generally the circles or ellipses were small1 and sometimes the course pursued was quite irregular4 ,an internode1 after making several revolutions1 sometimes stood still for #ab hrs4 or #ah hrs41 and then recommenced revolving4 ,such strongly marked interruptions in the movements of the internodes ,i have observed in hardly any other plant4 ,the leaves bear four leaflets1 themselves subdivided1 and terminate in much-branched tendrils4 ,the main petiole of the leaf1 whilst young1 moves spontaneously1 and follows nearly the same irregular course and at about the same rate as the internodes4 ,the movement to and from the stem is the most conspicuous1 and ,i have seen the chord of a curved petiole which formed an angle of #ei with the stem1 in an hour afterwards making an angle of #ajf4 ,the two opposite petioles do not move together1 and one is sometimes so much raised as to stand close to the stem1 whilst the other is not far from horizontal4 ,the basal part of the petiole moves less than the distal part4 ,the tendrils1 besides being carried by the moving petioles and internodes1 themselves move spontaneously2 and the opposite tendrils occasionally move in opposite directions4 ,by these combined movements of the young internodes1 petioles1 and tendrils1 a considerable space is swept in search of a support4 ,in young plants the tendrils are about three inches in length3 they bear two lateral and two terminal branches2 and each branch bifurcates twice1 with the tips terminating in blunt double hooks1 having both points directed to the same side4 ,all the branches are sensitive on all sides2 and after being lightly rubbed1 or after coming into contact with a stick1 bend in about #aj m4 ,one which had become curved in #aj m4 after a light rub1 continued bending for between #c hrs4 and #d hrs41 and became straight again in #h hrs4 or #i hrs4 ,tendrils1 which have caught nothing1 ultimately contract into an irregular spire1 as they likewise do1 only much more quickly1 after clasping a support4 ,in both cases the main petiole bearing the leaflets1 which is at first straight and inclined a little upwards1 moves downwards1 with the middle part bent abruptly into a right angle2 but this is seen in ,e4 miniatus more plainly than in ,e4 scaber4 ,the tendrils in this genus act in some respects like those of ,bignonia capreolata2 but the whole does not move from the light1 nor do the hooked tips become enlarged into cellular discs4 ,after the tendrils have come into contact with a moderately thick cylindrical stick or with rugged bark1 the several branches may be seen slowly to lift themselves up1 change their positions1 and again come into contact with the supporting surface4 ,the object of these movements is to bring the double-hooks at the extremities of the branches1 which naturally face in all directions1 into contact with the wood4 ,i have watched a tendril1 half of which had bent itself at right angles round the sharp corner of a square post1 neatly bring every single hook into contact with both rectangular surfaces4 ,the appearance suggested the belief1 that though the whole tendril is not sensitive to light1 yet that the tips are so1 and that they turn and twist themselves towards any dark surface4 ,ultimately the branches arrange themselves very neatly to all the irregularities of the most rugged bark1 so that they resemble in their irregular course a river with its branches1 as engraved on a map4 ,but when a tendril has wound round a rather thick stick1 the subsequent spiral contraction generally draws it away and spoils the neat arrangement4 ,so it is1 but not in quite so marked a manner1 when a tendril has spread itself over a large1 nearly flat surface of rugged bark4 ,we may therefore conclude that these tendrils are not perfectly adapted to seize moderately thick sticks or rugged bark4 ,if a thin stick or twig is placed near a tendril1 the terminal branches wind quite round it1 and then seize their own lower branches or the main stem4 ,the stick is thus firmly1 but not neatly1 grasped4 ,what the tendrils are really adapted for1 appears to be such objects as the thin culms of certain grasses1 or the long flexible bristles of a brush1 or thin rigid leaves such as those of the ,asparagus1 all of which they seize in an admirable manner4 ,this is due to the extremities of the branches close to the little hooks being extremely sensitive to a touch from the thinnest object1 which they consequently curl round and clasp4 ,when a small brush1 for instance1 was placed near a tendril1 the tips of each sub-branch seized one1 two1 or three of the bristles2 and then the spiral contraction of the several branches brought all these little parcels close together1 so that thirty or forty bristles were drawn into a single bundle1 which afforded an excellent support4 ,,polemoniace4--,coba scandens4--,this is an excellently constructed climber4 ,the tendrils on a fine plant were eleven inches long1 with the petiole bearing two pairs of leaflets1 only two and a half inches in length4 ,they revolve more rapidly and vigorously than those of any other tendril-bearer observed by me1 with the exception of one kind of ,passiflora4 ,three large1 nearly circular sweeps1 directed against the sun were completed1 each in #a hr4 #ae m42 and two other circles in #a hr4 #bj m4 and #a hr4 #bc m4 ,sometimes a tendril travels in a much inclined position1 and sometimes nearly upright4 ,the lower part moves but little and the petiole not at all2 nor do the internodes revolve2 so that here we have the tendril alone moving4 ,on the other hand1 with most of the species of ,bignonia and the ,eccremocarpus1 the internodes1 tendrils1 and petioles all revolved4 ,the long1 straight1 tapering main stem of the tendril of the ,coba bears alternate branches2 and each branch is several times divided1 with the finer branches as thin as very thin bristles and extremely flexible1 so that they are blown about by a breath of air2 yet they are strong and highly elastic4 ,the extremity of each branch is a little flattened1 and terminates in a minute double 7though sometimes single7 hook1 formed of a hard1 translucent1 woody substance1 and as sharp as the finest needle4 ,on a tendril which was eleven inches long ,i counted ninety-four of these beautifully constructed little hooks4 ,they readily catch soft wood1 or gloves1 or the skin of the naked hand4 ,with the exception of these hardened hooks1 and of the basal part of the central stem1 every part of every branchlet is highly sensitive on all sides to a slight touch1 and bends in a few minutes towards the touched side4 ,by lightly rubbing several sub-branches on opposite sides1 the whole tendril rapidly assumed an extraordinarily crooked shape4 ,these movements from contact do not interfere with the ordinary revolving movement4 ,the branches1 after becoming greatly curved from being touched1 straighten themselves at a quicker rate than in almost any other tendril seen by me1 namely1 in between half an hour and an hour4 ,after the tendril has caught any object1 spiral contraction likewise begins after an unusually short interval of time1 namely1 in about twelve hours4 ,before the tendril is mature1 the terminal branchlets cohere1 and the hooks are curled closely inwards4 ,at this period no part is sensitive to a touch2 but as soon as the branches diverge and the hooks stand out1 full sensitiveness is acquired4 ,it is a singular circumstance that immature tendrils revolve at their full velocity before they become sensitive1 but in a useless manner1 as in this state they can catch nothing4 ,this want of perfect co-adaptation1 though only for a short time1 between the structure and the functions of a climbing-plant is a rare event4 ,a tendril1 as soon as it is ready to act1 stands1 together with the supporting petiole1 vertically upwards4 ,the leaflets borne by the petiole are at this time quite small1 and the extremity of the growing stem is bent to one side so as to be out of the way of the revolving tendril1 which sweeps large circles directly over head4 ,the tendrils thus revolve in a position well adapted for catching objects standing above2 and by this means the ascent of the plant is favoured4 ,if no object is caught1 the leaf with its tendril bends downwards and ultimately assumes a horizontal position4 ,an open space is thus left for the next succeeding and younger tendril to stand vertically upwards and to revolve freely4 ,as soon as an old tendril bends downwards1 it loses all power of movement1 and contracts spirally into an entangled mass4 ,although the tendrils revolve with unusual rapidity1 the movement lasts for only a short time4 ,in a plant placed in the hot-house and growing vigorously1 a tendril revolved for not longer than #cf hours1 counting from the period when it first became sensitive2 but during this period it probably made at least #bg revolutions4 ,when a revolving tendril strikes against a stick1 the branches quickly bend round and clasp it4 ,the little hooks here play an important part1 as they prevent the branches from being dragged away by the rapid revolving movement1 before they have had time to clasp the stick securely4 ,this is especially the case when only the extremity of a branch has caught hold of a support4 ,as soon as a tendril has bent a smooth stick or a thick rugged post1 or has come into contact with planed wood 7for it can adhere temporarily even to so smooth a surface as this71 the same peculiar movements may be observed as those described under ,bignonia capreolata and ,eccremocarpus4 ,the branches repeatedly lift themselves up and down2 those which have their hooks already directed downwards remaining in this position and securing the tendril1 whilst the others twist about until they succeed in arranging themselves in conformity with every irregularity of the surface1 and in bringing their hooks into contact with the wood4 ,the use of the hooks was well shown by giving the tendrils tubes and slips of glass to catch2 for these1 though temporarily seized1 were invariably lost1 either during the re-arrangement of the branches or ultimately when spiral contraction ensued4 ,the perfect manner in which the branches arranged themselves1 creeping like rootlets over every inequality of the surface and into any deep crevice1 is a pretty sight2 for it is perhaps more effectually performed by this than by any other species4 ,the action is certainly more conspicuous1 as the upper surfaces of the main stem1 as well as of every branch to the extreme hooks1 are angular and green1 whilst the lower surfaces are rounded and purple4 ,i was led to infer1 as in former cases1 that a less amount of light guided these movements of the branches of the tendrils4 ,i made many trials with black and white cards and glass tubes to prove it1 but failed from various causes2 yet these trials countenanced the belief4 ,as a tendril consists of a leaf split into numerous segments1 there is nothing surprising in all the segments turning their upper surfaces towards the light1 as soon as the tendril is caught and the revolving movement is arrested4 ,but this will not account for the whole movement1 for the segments actually bend or curve to the dark side besides turning round on their axes so that their upper surfaces may face the light4 ,when the ,coba grows in the open air1 the wind must aid the extremely flexible tendrils in seizing a support1 for ,i found that a mere breath sufficed to cause the extreme branches to catch hold by their hooks of twigs1 which they could not have reached by the revolving movement4 ,it might have been thought that a tendril1 thus hooked by the extremity of a single branch1 could not have fairly grasped its support4 ,but several times ,i watched cases like the following3 tendril caught a thin stick by the hooks of one of its two extreme branches2 though thus held by the tip1 it still tried to revolve1 bowing itself to all sides1 and by this movement the other extreme branch soon caught the stick4 ,the first branch then loosed itself1 and1 arranging its hooks1 again caught hold4 ,after a time1 from the continued movement of the tendril1 the hooks of a third branch caught hold4 ,no other branches1 as the tendril then stood1 could possibly have touched the stick4 ,but before long the upper part of the main stem began to contract into an open spire4 ,it thus dragged the shoot which bore the tendril towards the stick2 and as the tendril continually tried to revolve1 a fourth branch was brought into contact4 ,and lastly1 from the spiral contraction travelling down both the main stem and the branches1 all of them1 one after another1 were ultimately brought into contact with the stick4 ,they then wound themselves round it and round one another1 until the whole tendril was tied together in an inextricable knot4 ,the tendrils1 though at first quite flexible1 after having clasped a support for a time1 become more rigid and stronger than they were at first4 ,thus the plant is secured to its support in a perfect manner4 ,,leguminos4--,pisum sativum4--,the common pea was the subject of a valuable memoir by ,dutrochet1 #aaa who discovered that the internodes and tendrils revolve in ellipses4 ,the ellipses are generally very narrow1 but sometimes approach to circles4 ,i several times observed that the longer axis slowly changed its direction1 which is of importance1 as the tendril thus sweeps a wider space4 ,owing to this change of direction1 and likewise to the movement of the stem towards the light1 the successive irregular ellipses generally form an irregular spire4 ,i have thought it worth while to annex a tracing of the course pursued by the upper internode 7the movement of the tendril being neglected7 of a young plant from #h4dj ,a4,m4 to #i4ae ,p4,m4 ,the course was traced on a hemispherical glass placed over the plant1 and the dots with figures give the hours of observation2 each dot being joined by a straight line4 ,no doubt all the lines would have been curvilinear if the course had been observed at much shorter intervals4 ,the extremity of the petiole1 from which the young tendril arose1 was two inches from the glass1 so that if a pencil two inches in length could have been affixed to the petiole1 it would have traced the annexed figure on the under side of the glass2 but it must be remembered that the figure is reduced by one-half4 ,neglecting the first great sweep towards the light from the figure #a to #b1 the end of the petiole swept a space #d inches across in one direction1 and #c inches in another4 ,as a full-grown tendril is considerably above two inches in length1 and as the tendril itself bends and revolves in harmony with the internode1 a considerably wider space is swept than is here represented on a reduced scale4 ,dutrochet observed the completion of an ellipse in #a hr4 #bj m42 and ,i saw one completed in #a hr4 #cj m4 ,the direction followed is variable1 either with or against the sun4 ,picture3 ,fig4 #f4 ,side of room with window #aac ,dutrochet asserts that the petioles of the leaves spontaneously revolve1 as well as the young internodes and tendrils2 but he does not say that he secured the internodes2 when this was done1 ,i could never detect any movement in the petiole1 except to and from the light4 ,the tendrils1 on the other hand1 when the internodes and petioles are secured1 describe irregular spires or regular ellipses1 exactly like those made by the internodes4 ,a young tendril1 only #a of an inch in length1 revolved4 ,dutrochet has shown that when a plant is placed in a room1 so that the light enters laterally1 the internodes travel much quicker to the light than from it3 on the other hand1 he asserts that the tendril itself moves from the light towards the dark side of the room4 ,with due deference to this great observer1 ,i think he was mistaken1 owing to his not having secured the internodes4 ,i took a young plant with highly sensitive tendrils1 and tied the petiole so that the tendril alone could move2 it completed a perfect ellipse in #a hr4 #cj m42 ,i then turned the plant partly round1 but this made no change in the direction of the succeeding ellipse4 ,the next day ,i watched a plant similarly secured until the tendril 7which was highly sensitive7 made an ellipse in a line exactly to and from the light2 the movement was so great that the tendril at the two ends of its elliptical course bent itself a little beneath the horizon1 thus travelling more than #ahj degrees2 but the curvature was fully as great towards the light as towards the dark side of the room4 ,i believe ,dutrochet was misled by not having secured the internodes1 and by having observed a plant of which the internodes and tendrils no longer curved in harmony together1 owing to inequality of age4 ,dutrochet made no observations on the sensitiveness of the tendrils4 ,these1 whilst young and about an inch in length with the leaflets on the petiole only partially expanded1 are highly sensitive2 a single light touch with a twig on the inferior or concave surface near the tip caused them to bend quickly1 as did occasionally a loop of thread weighing one-seventh of a grain 7#i4be mg474 ,the upper or convex surface is barely or not at all sensitive4 ,tendrils1 after bending from a touch1 straighten themselves in about two hours1 and are then ready to act again4 ,as soon as they begin to grow old1 the extremities of their two or three pairs of branches become hooked1 and they then appear to form an excellent grappling instrument2 but this is not the case4 ,for at this period they have generally quite lost their sensitiveness2 and when hooked on to twigs1 some were not at all affected1 and others required from #ah hrs4 to #bd hrs4 before clasping such twigs2 nevertheless1 they were able to utilise the last vestige of irritability owing to their extremities being hooked4 ,ultimately the lateral branches contract spirally1 but not the middle or main stem4 ,lathyrus aphaca4--,this plant is destitute of leaves1 except during a very early age1 these being replaced by tendrils1 and the leaves themselves by large stipules4 ,it might therefore have been expected that the tendrils would have been highly organized1 but this is not so4 ,they are moderately long1 thin1 and unbranched1 with their tips slightly curved4 ,whilst young they are sensitive on all sides1 but chiefly on the concave side of the extremity4 ,they have no spontaneous revolving power1 but are at first inclined upwards at an angle of about #de1 then move into a horizontal position1 and ultimately bend downwards4 ,the young internodes1 on the other hand1 revolve in ellipses1 and carry with them the tendrils4 ,two ellipses were completed1 each in nearly #e hrs42 their longer axes were directed at about an angle of #de to the axis of the previously made ellipse4 ,lathyrus grandiflorus4--,the plants observed were young and not growing vigorously1 yet sufficiently so1 ,i think1 for my observations to be trusted4 ,if so1 we have the rare case of neither internodes nor tendrils revolving4 ,the tendrils of vigorous plants are above #d inches in length1 and are often twice divided into three branches2 the tips are curved and are sensitive on their concave sides2 the lower part of the central stem is hardly at all sensitive4 ,hence this plant appears to climb simply by its tendrils being brought1 through the growth of the stem1 or more efficiently by the wind1 into contact with surrounding objects1 which they then clasp4 ,i may add that the tendrils1 or the internodes1 or both1 of ,vicia sativa revolve4 ,,composit4--,mutisia clematis4--,the immense family of the ,composit is well known to include very few climbing plants4 ,we have seen in the ,table in the first chapter that ,mikania scandens is a regular twiner1 and ,f4 ,mller informs me that in ,s4 ,brazil there is another species which is a leaf-climber4 ,mutisia is the only genus in the family1 as far as ,i can learn1 which bears tendrils3 it is therefore interesting to find that these1 though rather less metamorphosed from their primordial foliar condition than are most other tendrils1 yet display all the ordinary characteristic movements1 both those that are spontaneous and those which are excited by contact4 ,the long leaf bears seven or eight alternate leaflets1 and terminates in a tendril which1 in a plant of considerable size1 was #e inches in length4 ,it consists generally of three branches2 and these1 although much elongated1 evidently represent the petioles and midribs of three leaflets2 for they closely resemble the same parts in an ordinary leaf1 in being rectangular on the upper surface1 furrowed1 and edged with green4 ,moreover1 the green edging of the tendrils of young plants sometimes expands into a narrow lamina or blade4 ,each branch is curved a little downwards1 and is slightly hooked at the extremity4 ,a young upper internode revolved1 judging from three revolutions1 at an average rate of #a hr4 #ch m42 it swept ellipses with the longer axes directed at right angles to one another2 but the plant1 apparently1 cannot twine4 ,the petioles and the tendrils are both in constant movement4 ,but their movement is slower and much less regularly elliptical than that of the internodes4 ,they appear to be much affected by the light1 for the whole leaf usually sinks down during the night and rises during the day1 moving1 also1 during the day in a crooked course to the west4 ,the tip of the tendril is highly sensitive on the lower surface2 and one which was just touched with a twig became perceptibly curved in #c m41 and another in #e m42 the upper surface is not at all sensitive2 the sides are moderately sensitive1 so that two branches which were rubbed on their inner sides converged and crossed each other4 ,the petiole of the leaf and the lower parts of the tendril1 halfway between the upper leaflet and the lowest branch1 are not sensitive4 ,a tendril after curling from a touch became straight again in about #f hrs41 and was ready to re-act2 but one that had been so roughly rubbed as to have coiled into a helix did not become perfectly straight until after #ac hrs4 ,the tendrils retain their sensibility to an unusually late age2 for one borne by a leaf with five or six fully developed leaves above1 was still active4 ,if a tendril catches nothing1 after a considerable interval of time the tips of the branches curl a little inwards2 but if it clasps some object1 the whole contracts spirally4 ,picture3 ,fig4 #g4 ,smilax aspera ,,smilace4--,smilax aspera1 var4 maculata4--,aug4 ,st4-,hilaire #aah considers that the tendrils1 which rise in pairs from the petiole1 are modified lateral leaflets2 but ,mohl 7p4 #da7 ranks them as modified stipules4 ,these tendrils are from #a to #a inches in length1 are thin1 and have slightly curved1 pointed extremities4 ,they diverge a little from each other1 and stand at first nearly upright4 ,when lightly rubbed on either side1 they slowly bend to that side1 and subsequently become straight again4 ,the back or convex side when placed in contact with a stick became just perceptibly curved in #a hr4 #bj m41 but did not completely surround it until #dh hrs4 had elapsed2 the concave side of another became considerably curved in #b hrs4 and clasped a stick in #e hrs4 ,as the pairs of tendrils grow old1 one tendril diverges more and more from the other1 and both slowly bend backwards and downwards1 so that after a time they project on the opposite side of the stem to that from which they arise4 ,they then still retain their sensitiveness1 and can clasp a support placed behind the stem4 ,owing to this power1 the plant is able to ascend a thin upright stick4 ,ultimately the two tendrils belonging to the same petiole1 if they do not come into contact with any object1 loosely cross each other behind the stem1 as at ,b1 in fig4 #g4 ,this movement of the tendrils towards and round the stem is1 to a certain extent1 guided by their avoidance of the light2 for when a plant stood so that one of the two tendrils was compelled in thus slowly moving to travel towards the light1 and the other from the light1 the latter always moved1 as ,i repeatedly observed1 more quickly than its fellow4 ,the tendrils do not contract spirally in any case4 ,their chance of finding a support depends on the growth of the plant1 on the wind1 and on their own slow backward and downward movement1 which1 as we have just seen1 is guided1 to a certain extent1 by the avoidance of the light2 for neither the internodes nor the tendrils have any proper revolving movement4 ,from this latter circumstance1 from the slow movements of the tendrils after contact 7though their sensitiveness is retained for an unusual length of time71 from their simple structure and shortness1 this plant is a less perfect climber than any other tendril-bearing species observed by me4 ,the plant whilst young and only a few inches in height1 does not produce any tendrils2 and considering that it grows to only about #h feet in height1 that the stem is zigzag and is furnished1 as well as the petioles1 with spines1 it is surprising that it should be provided with tendrils1 comparatively inefficient though these are4 ,the plant might have been left1 one would have thought1 to climb by the aid of its spines alone1 like our brambles4 ,as1 however1 it belongs to a genus1 some of the species of which are furnished with much longer tendrils1 we may suspect that it possesses these organs solely from being descended from progenitors more highly organized in this respect4 ,,fumariace4--,corydalis claviculata4--,according to ,mohl 7p4 #dc71 the extremities of the branched stem1 as well as the leaves1 are converted into tendrils4 ,in the specimens examined by me all the tendrils were certainly foliar1 and it is hardly credible that the same plant should produce tendrils of a widely different homological nature4 ,nevertheless1 from this statement by ,mohl1 ,i have ranked this species amongst the tendril-bearers2 if classed exclusively by its foliar tendrils1 it would be doubtful whether it ought not to have been placed amongst the leaf-climbers1 with its allies1 ,fumaria and ,adlumia4 ,a large majority of its so-called tendrils still bear leaflets1 though excessively reduced in size2 but some few of them may properly be designated as tendrils1 for they are completely destitute of lamin or blades4 ,consequently1 we here behold a plant in an actual state of transition from a leaf-climber to a tendril-bearer4 ,whilst the plant is rather young1 only the outer leaves1 but when full-grown all the leaves1 have their extremities converted into more or less perfect tendrils4 ,i have examined specimens from one locality alone1 viz4 ,hampshire2 and it is not improbable that plants growing under different conditions might have their leaves a little more or less changed into true tendrils4 ,whilst the plant is quite young1 the first-formed leaves are not modified in any way1 but those next formed have their terminal leaflets reduced in size1 and soon all the leaves assume the structure represented in the following drawing4 ,this leaf bore nine leaflets2 the lower ones being much subdivided4 ,the terminal portion of the petiole1 about #a inch in length 7above the leaflet f71 is thinner and more elongated than the lower part1 and may be considered as the tendril4 ,the leaflets borne by this part are greatly reduced in size1 being1 on an average1 about the tenth of an inch in length and very narrow2 one small leaflet measured one-twelfth of an inch in length and one-seventy-fifth in breadth 7#b4aaf mm4 and #j4cci mm471 so that it was almost microscopically minute4 ,all the reduced leaflets have branching nerves1 and terminate in little spines1 like those of the fully developed leaflets4 ,every gradation could be traced1 until we come to branchlets 7as a and d in the figure7 which show no vestige of a lamina or blade4 ,occasionally all the terminal branchlets of the petiole are in this condition1 and we then have a true tendril4 ,picture3 ,fig4 #h4 ,corydalis claviculata4 ,leaf-tendril of natural size ,the several terminal branches of the petiole bearing the much reduced leaflets 7a1 b1 c1 d7 are highly sensitive1 for a loop of thread weighing only the one-sixteenth of a grain 7#d4je mg47 caused them to become greatly curved in under #d hrs4 ,when the loop was removed1 the petioles straightened themselves in about the same time4 ,the petiole 7e7 was rather less sensitive2 and in another specimen1 in which the corresponding petiole bore rather larger leaflets1 a loop of thread weighing one-eighth of a grain did not cause curvature until #ah hrs4 had elapsed4 ,loops of thread weighing one-fourth of a grain1 left suspended on the lower petioles 7f to l7 during several days1 produced no effect4 ,yet the three petioles f1 g1 and h were not quite insensible1 for when left in contact with a stick for a day or two they slowly curled round it4 ,thus the sensibility of the petiole gradually diminishes from the tendril-like extremity to the base4 ,the internodes of the stem are not at all sensitive1 which makes ,mohl's statement that they are sometimes converted into tendrils the more surprising1 not to say improbable4 ,the whole leaf1 whilst young and sensitive1 stands almost vertically upwards1 as we have seen to be the case with many tendrils4 ,it is in continual movement1 and one that ,i observed swept at an average rate of about #b hrs4 for each revolution1 large1 though irregular1 ellipses1 which were sometimes narrow1 sometimes broad1 with their longer axes directed to different points of the compass4 ,the young internodes1 likewise revolved irregularly in ellipses or spires2 so that by these combined movements a considerable space was swept for a support4 ,if the terminal and attenuated portion of a petiole fails to seize any object1 it ultimately bends downwards and inwards1 and soon loses all irritability and power of movement4 ,this bending down differs much in nature from that which occurs with the extremities of the young leaves in many species of ,clematis2 for these1 when thus bent downwards or hooked1 first acquire their full degree of sensitiveness4 ,dicentra thalictrifolia4--,in this allied plant the metamorphosis of the terminal leaflets is complete1 and they are converted into perfect tendrils4 ,whilst the plant is young1 the tendrils appear like modified branches1 and a distinguished botanist thought that they were of this nature2 but in a full-grown plant there can be no doubt1 as ,i am assured by ,dr4 ,hooker1 that they are modified leaves4 ,when of full size1 they are above #e inches in length2 they bifurcate twice1 thrice1 or even four times2 their extremities are hooked and blunt4 ,all the branches of the tendrils are sensitive on all sides1 but the basal portion of the main stem is only slightly so4 ,the terminal branches when lightly rubbed with a twig became curved in the course of from #cj m4 to #db m41 and straightened themselves in between #aj hrs4 and #bj hrs4 ,a loop of thread weighing one-eighth of a grain plainly caused the thinner branches to bend1 as did occasionally a loop weighing one-sixteenth of a grain2 but this latter weight1 though left suspended1 was not sufficient to cause a permanent flexure4 ,the whole leaf with its tendril1 as well as the young upper internodes1 revolves vigorously and quickly1 though irregularly1 and thus sweeps a wide space4 ,the figure traced on a bell-glass was either an irregular spire or a zigzag line4 ,the nearest approach to an ellipse was an elongated figure of #h1 with one end a little open1 and this was completed in #a hr4 #ec m4 ,during a period of #f hrs4 #ag m4 another shoot made a complex figure1 apparently representing three and a half ellipses4 ,when the lower part of the petiole bearing the leaflets was securely fastened1 the tendril itself described similar but much smaller figures4 ,this species climbs well4 ,the tendrils after clasping a stick become thicker and more rigid2 but the blunt hooks do not turn and adapt themselves to the supporting surface1 as is done in so perfect a manner by some ,bignoniace and ,coba4 ,the tendrils of young plants1 two or three feet in height1 are only half the length of those borne by the same plant when grown taller1 and they do not contract spirally after clasping a support1 but only become slightly flexuous4 ,full-sized tendrils1 on the other hand1 contract spirally1 with the exception of the thick basal portion4 ,tendrils which have caught nothing simply bend downwards and inwards1 like the extremities of the leaves of the ,corydalis claviculata4 ,but in all cases the petiole after a time is angularly and abruptly bent downwards like that of ,eccremocarpus4 ,,chapter ,,iv4 ,,tendril-,,bearers--7continued74 ,,cucurbitace4--,homologous nature of the tendrils--,echinocystis lobata1 remarkable movements of the tendrils to avoid seizing the terminal shoot--,tendrils not excited by contact with another tendril or by drops of water--,undulatory movement of the extremity of the tendril--,hanburya1 adherent discs--,,vitac--,gradation between the flower-peduncles and tendrils of the vine--,tendrils of the ,virginian ,creeper turn from the light1 and1 after contact1 develop adhesive discs--,,sapindace--,,passiflorace--,pas siflora gracilis--,rapid revolving movement and sensitiveness of the tendrils--,not sensitive to the contact of other tendrils or of drops of water--,spiral contraction of tendrils--,summary on the nature and action of tendrils4 ,,cucurbitace4--,the tendrils in this family have been ranked by competent judges as modified leaves1 stipules1 or branches2 or as partly a leaf and partly a branch4 ,de ,candolle believes that the tendrils differ in their homological nature in two of the tribes4 #abg;a ,from facts recently adduced1 ,mr4 ,berkeley thinks that ,payer's view is the most probable1 namely1 that the tendril is 8a separate portion of the leaf itself20 but much may be said in favour of the belief that it is a modified flower-peduncle4 #abg;b ,echinocystis lobata4--,numerous observations were made on this plant 7raised from seed sent me by ,prof4 ,asa ,gray71 for the spontaneous revolving movements of the internodes and tendrils were first observed by me in this case1 and greatly perplexed me4 ,my observations may now be much condensed4 ,i observed thirty-five revolutions of the internodes and tendrils2 the slowest rate was #b hrs4 and the average rate1 with no great fluctuations1 #a hr4 #dj m4 ,sometimes ,i tied the internodes1 so that the tendrils alone moved2 at other times ,i cut off the tendrils whilst very young1 so that the internodes revolved by themselves2 but the rate was not thus affected4 ,the course generally pursued was with the sun1 but often in an opposite direction4 ,sometimes the movement during a short time would either stop or be reversed2 and this apparently was due to interference from the light1 as1 for instance1 when ,i placed a plant close to a window4 ,in one instance1 an old tendril1 which had nearly ceased revolving1 moved in one direction1 whilst a young tendril above moved in an opposite course4 ,the two uppermost internodes alone revolve2 and as soon as the lower one grows old1 only its upper part continues to move4 ,the ellipses or circles swept by the summits of the internodes are about three inches in diameter2 whilst those swept by the tips of the tendrils1 are from #ae to #af inches in diameter4 ,during the revolving movement1 the internodes become successively curved to all points of the compass2 in one part of their course they are often inclined1 together with the tendrils1 at about #de to the horizon1 and in another part stand vertically up4 ,there was something in the appearance of the revolving internodes which continually gave the false impression that their movement was due to the weight of the long and spontaneously revolving tendril2 but1 on cutting off the latter with sharp scissors1 the top of the shoot rose only a little1 and went on revolving4 ,this false appearance is apparently due to the internodes and tendrils all curving and moving harmoniously together4 ,a revolving tendril1 though inclined during the greater part of its course at an angle of about #de 7in one case of only #cg7 above the horizon1 stiffened and straightened itself from tip to base in a certain part of its course1 thus becoming nearly or quite vertical4 ,i witnessed this repeatedly2 and it occurred both when the supporting internodes were free and when they were tied up2 but was perhaps most conspicuous in the latter case1 or when the whole shoot happened to be much inclined4 ,the tendril forms a very acute angle with the projecting extremity of the stem or shoot2 and the stiffening always occurred as the tendril approached1 and had to pass over the shoot in its circular course4 ,if it had not possessed and exercised this curious power1 it would infallibly have struck against the extremity of the shoot and been arrested4 ,as soon as the tendril with its three branches begins to stiffen itself in this manner and to rise from an inclined into a vertical position1 the revolving motion becomes more rapid2 and as soon as the tendril has succeeded in passing over the extremity of the shoot or point of difficulty1 its motion1 coinciding with that from its weight1 often causes it to fall into its previously inclined position so quickly1 that the apex could be seen travelling like the minute hand of a gigantic clock4 ,the tendrils are thin1 from #g to #i inches in length1 with a pair of short lateral branches rising not far from the base4 ,the tip is slightly and permanently curved1 so as to act to a limited extent as a hook4 ,the concave side of the tip is highly sensitive to a touch2 but not so the convex side1 as was likewise observed to be the case with other species of the family by ,mohl 7p4 #fe74 ,i repeatedly proved this difference by lightly rubbing four or five times the convex side of one tendril1 and only once or twice the concave side of another tendril1 and the latter alone curled inwards4 ,in a few hours afterwards1 when the tendrils which had been rubbed on the concave side had straightened themselves1 ,i reversed the process of rubbing1 and always with the same result4 ,after touching the concave side1 the tip becomes sensibly curved in one or two minutes2 and subsequently1 if the touch has been at all rough1 it coils itself into a helix4 ,but the helix will1 after a time1 straighten itself1 and be again ready to act4 ,a loop of thin thread only one-sixteenth of a grain in weight caused a temporary flexure4 ,the lower part was repeatedly rubbed rather roughly1 but no curvature ensued2 yet this part is sensitive to prolonged pressure1 for when it came into contact with a stick1 it would slowly wind round it4 ,one of my plants bore two shoots near together1 and the tendrils were repeatedly drawn across one another1 but it is a singular fact that they did not once catch each other4 ,it would appear as if they had become habituated to contact of this kind1 for the pressure thus caused must have been much greater than that caused by a loop of soft thread weighing only the one-sixteenth of a grain4 ,i have1 however1 seen several tendrils of ,bryonia dioica interlocked1 but they subsequently released one another4 ,the tendrils of the ,echinocystis are also habituated to drops of water or to rain2 for artificial rain made by violently flirting a wet brush over them produced not the least effect4 ,the revolving movement of a tendril is not stopped by the curving of its extremity after it has been touched4 ,when one of the lateral branches has firmly clasped an object1 the middle branch continues to revolve4 ,when a stem is bent down and secured1 so that the tendril depends but is left free to move1 its previous revolving movement is nearly or quite stopped2 but it soon begins to bend upwards1 and as soon as it has become horizontal the revolving movement recommences4 ,i tried this four times2 the tendril generally rose to a horizontal position in an hour or an hour and a half2 but in one case1 in which a tendril depended at an angle of #de beneath the horizon1 the uprising took two hours2 in half an hour afterwards it rose to #bc above the horizon and then recommenced revolving4 ,this upward movement is independent of the action of light1 for it occurred twice in the dark1 and on another occasion the light came in on one side alone4 ,the movement no doubt is guided by opposition to the force of gravity1 as in the case of the ascent of the plumules of germinating seeds4 ,a tendril does not long retain its revolving power2 and as soon as this is lost1 it bends downwards and contracts spirally4 ,after the revolving movement has ceased1 the tip still retains for a short time its sensitiveness to contact1 but this can be of little or no use to the plant4 ,though the tendril is highly flexible1 and though the extremity travels1 under favourable circumstances1 at about the rate of an inch in two minutes and a quarter1 yet its sensitiveness to contact is so great that it hardly ever fails to seize a thin stick placed in its path4 ,the following case surprised me much3 ,i placed a thin1 smooth1 cylindrical stick 7and ,i repeated the experiment seven times7 so far from a tendril1 that its extremity could only curl half or three-quarters round the stick2 but ,i always found that the tip managed in the course of a few hours to curl twice or even thrice round the stick4 ,i at first thought that this was due to rapid growth on the outside2 but by coloured points and measurements ,i proved that there had been no sensible increase of length within the time4 ,when a stick1 flat on one side1 was similarly placed1 the tip of the tendril could not curl beyond the flat surface1 but coiled itself into a helix1 which1 turning to one side1 lay flat on the little flat surface of wood4 ,in one instance a portion of tendril three-quarters of an inch in length was thus dragged on to the flat surface by the coiling in of the helix4 ,but the tendril thus acquires a very insecure hold1 and generally after a time slips off4 ,in one case alone the helix subsequently uncoiled itself1 and the tip then passed round and clasped the stick4 ,the formation of the helix on the flat side of the stick apparently shows us that the continued striving of the tip to curl itself closely inwards gives the force which drags the tendril round a smooth cylindrical stick4 ,in this latter case1 whilst the tendril was slowly and quite insensibly crawling onwards1 ,i observed several times through a lens that the whole surface was not in close contact with the stick2 and ,i can understand the onward progress only by supposing that the movement is slightly undulatory or vermicular1 and that the tip alternately straightens itself a little and then again curls inwards4 ,it thus drags itself onwards by an insensibly slow1 alternate movement1 which may be compared to that of a strong man suspended by the ends of his fingers to a horizontal pole1 who works his fingers onwards until he can grasp the pole with the palm of his hand4 ,however this may be1 the fact is certain that a tendril which has caught a round stick with its extreme point1 can work itself onwards until it has passed twice or even thrice round the stick1 and has permanently grasped it4 ,hanburya ,mexicana4--,the young internodes and tendrils of this anomalous member of the family1 revolve in the same manner and at about the same rate as those of the ,echinocystis4 ,the stem does not twine1 but can ascend an upright stick by the aid of its tendrils4 ,the concave tip of the tendril is very sensitive2 after it had become rapidly coiled into a ring owing to a single touch1 it straightened itself in #ej m4 ,the tendril1 when in full action1 stands vertically up1 with the projecting extremity of the young stem thrown a little on one side1 so as to be out of the way2 but the tendril bears on the inner side1 near its base1 a short rigid branch1 which projects out at right angles like a spur1 with the terminal half bowed a little downwards4 ,hence1 as the main vertical branch revolves1 the spur1 from its position and rigidity1 cannot pass over the extremity of the shoot1 in the same curious manner as do the three branches of the tendril of the ,echinocystis1 namely1 by stiffening themselves at the proper point4 ,the spur is therefore pressed laterally against the young stem in one part of the revolving course1 and thus the sweep of the lower part of the main branch is much restricted4 ,a nice case of co-adaptation here comes into play3 in all the other tendrils observed by me1 the several branches become sensitive at the same period3 had this been the case with the ,hanburya1 the inwardly directed1 spur-like branch1 from being pressed1 during the revolving movement1 against the projecting end of the shoot1 would infallibly have seized it in a useless or injurious manner4 ,but the main branch of the tendril1 after revolving for a time in a vertical position1 spontaneously bends downwards2 and in doing so1 raises the spur-like branch1 which itself also curves upwards2 so that by these combined movements it rises above the projecting end of the shoot1 and can now move freely without touching the shoot2 and now it first becomes sensitive4 ,the tips of both branches1 when they come into contact with a stick1 grasp it like any ordinary tendril4 ,but in the course of a few days1 the lower surface swells and becomes developed into a cellular layer1 which adapts itself closely to the wood1 and firmly adheres to it4 ,this layer is analogous to the adhesive discs formed by the extremities of the tendrils of some species of ,bignonia and of ,ampelopsis2 but in the ,hanburya the layer is developed along the terminal inner surface1 sometimes for a length of #a inches1 and not at the extreme tip4 ,the layer is white1 whilst the tendril is green1 and near the tip it is sometimes thicker than the tendril itself2 it generally spreads a little beyond the sides of the tendril1 and is fringed with free elongated cells1 which have enlarged globular or retort-shaped heads4 ,this cellular layer apparently secretes some resinous cement2 for its adhesion to the wood was not lessened by an immersion of #bd hrs4 in alcohol or water1 but was quite loosened by a similar immersion in ether or turpentine4 ,after a tendril has once firmly coiled itself round a stick1 it is difficult to imagine of what use the adhesive cellular layer can be4 ,owing to the spiral contraction which soon ensues1 the tendrils were never able to remain1 excepting in one instance1 in contact with a thick post or a nearly flat surface2 if they had quickly become attached by means of the adhesive layer1 this would evidently have been of service to the plant4 ,the tendrils of ,bryonia dioica1 ,cucurbita ovifera1 and ,cucumis sativa are sensitive and revolve4 ,whether the internodes likewise revolve ,i did not observe4 ,in ,anguria ,warscewiczii1 the internodes1 though thick and stiff1 revolve3 in this plant the lower surface of the tendril1 some time after clasping a stick1 produces a coarsely cellular layer or cushion1 which adapts itself closely to the wood1 like that formed by the tendril of the ,hanburya2 but it is not in the least adhesive4 ,in ,zanonia ,indica1 which belongs to a different tribe of the family1 the forked tendrils and the internodes revolve in periods between #b hrs4 #h m4 and #c hrs4 #ce m41 moving against the sun4 ,,vitace4--,in this family and in the two following1 namely1 the ,sapindac and ,passiflorace1 the tendrils are modified flower-peduncles2 and are therefore axial in their nature4 ,in this respect they differ from all those previously described1 with the exception1 perhaps1 of the ,cucurbitace4 ,the homological nature1 however1 of a tendril seems to make no difference in its action4 ,picture3 ,fig4 #i4 ,tendril of the ,vine4 ,a4 ,peduncle of tendril4 ,b4 ,longer ,branch1 with a scale at its base4 ,c4 ,shorter branch4 ,d4 ,petiole of the opposite leaf ,vitis vinifera4--,the tendril is thick and of great length2 one from a vine growing out of doors and not vigorously1 was #af inches long4 ,it consists of a peduncle 7,a71 bearing two branches which diverge equally from it4 ,one of the branches 7,b7 has a scale at its base2 it is always1 as far as ,i have seen1 longer than the other and often bifurcates4 ,the branches when rubbed become curved1 and subsequently straighten themselves4 ,after a tendril has clasped any object with its extremity1 it contracts spirally2 but this does not occur 7,palm1 p4 #ef7 when no object has been seized4 ,the tendrils move spontaneously from side to side2 and on a very hot day1 one made two elliptical revolutions1 at an average rate of #b hrs4 #ae m4 ,during these movements a coloured line1 painted along the convex surface1 appeared after a time on one side1 then on the concave side1 then on the opposite side1 and lastly again on the convex side4 ,the two branches of the same tendril have independent movements4 ,after a tendril has spontaneously revolved for a time1 it bends from the light towards the dark3 ,i do not state this on my own authority1 but on that of ,mohl and ,dutrochet4 ,mohl 7p4 #gg7 says that in a vine planted against a wall the tendrils point towards it1 and in a vineyard generally more or less to the north4 ,the young internodes revolve spontaneously2 but the movement is unusually slight4 ,a shoot faced a window1 and ,i traced its course on the glass during two perfectly calm and hot days4 ,on one of these days it described1 in the course of ten hours1 a spire1 representing two and a half ellipses4 ,i also placed a bell-glass over a young ,muscat grape in the hot-house1 and it made each day three or four very small oval revolutions2 the shoot moving less than half an inch from side to side4 ,had it not made at least three revolutions whilst the sky was uniformly overcast1 ,i should have attributed this slight degree of movement to the varying action of the light4 ,the extremity of the stem is more or less bent downwards1 but it never reverses its curvature1 as so generally occurs with twining plants4 ,picture3 ,fig4 #aj4 ,flower-stalk of the ,vine4 ,a4 ,common ,peduncle4 ,b4 ,flower-tendril4 ,c4 ,sub-,peduncle1 bearing the flower-buds4 ,d4 ,petiole of the opposite leaf ,various authors 7,palm1 p4 #ee2 ,mohl1 p4 #de2 ,lindley1 c47 believe that the tendrils of the vine are modified flower-peduncles4 ,i here give a drawing 7fig4 #aj7 of the ordinary state of a young flower-stalk3 it consists of the 8common peduncle0 7,a72 of the 8flower-tendril0 7,b71 which is represented as having caught a twig2 and of the 8sub-peduncle0 7,c7 bearing the flower-buds4 ,the whole moves spontaneously1 like a true tendril1 but in a less degree2 the movement1 however1 is greater when the sub-peduncle 7,c7 does not bear many flower-buds4 ,the common peduncle 7,a7 has not the power of clasping a support1 nor has the corresponding part of a true tendril4 ,the flower-tendril 7,b7 is always longer than the sub-peduncle 7,c7 and has a scale at its base2 it sometimes bifurcates1 and therefore corresponds in every detail with the longer scale-bearing branch 7,b1 fig4 #i7 of the true tendril4 ,it is1 however1 inclined backwards from the sub-peduncle 7,c71 or stands at right angles with it1 and is thus adapted to aid in carrying the future bunch of grapes4 ,when rubbed1 it curves and subsequently straightens itself2 and it can1 as is shown in the drawing1 securely clasp a support4 ,i have seen an object as soft as a young vine-leaf caught by one4 ,the lower and naked part of the sub-peduncle 7,c7 is likewise slightly sensitive to a rub1 and ,i have seen it bent round a stick and even partly round a leaf with which it had come into contact4 ,that the sub-peduncle has the same nature as the corresponding branch of an ordinary tendril1 is well shown when it bears only a few flowers2 for in this case it becomes less branched1 increases in length1 and gains both in sensitiveness and in the power of spontaneous movement4 ,i have twice seen sub-peduncles which bore from thirty to forty flower-buds1 and which had become considerably elongated and were completely wound round sticks1 exactly like true tendrils4 ,the whole length of another sub-peduncle1 bearing only eleven flower-buds1 quickly became curved when slightly rubbed2 but even this scanty number of flowers rendered the stalk less sensitive than the other branch1 that is1 the flower-tendril2 for the latter after a lighter rub became curved more quickly and in a greater degree4 ,i have seen a sub-peduncle thickly covered with flower-buds1 with one of its higher lateral branchlets bearing from some cause only two buds2 and this one branchlet had become much elongated and had spontaneously caught hold of an adjoining twig2 in fact1 it formed a little sub-tendril4 ,the increasing length of the sub-peduncle 7,c7 with the decreasing number of the flower-buds is a good instance of the law of compensation4 ,in accordance with this same principle1 the true tendril as a whole is always longer than the flower-stalk2 for instance1 on the same plant1 the longest flower-stalk 7measured from the base of the common peduncle to the tip of the flower-tendril7 was #h inches in length1 whilst the longest tendril was nearly double this length1 namely #af inches4 ,the gradations from the ordinary state of a flower-stalk1 as represented in the drawing 7fig4 #aj71 to that of a true tendril 7fig4 #i7 are complete4 ,we have seen that the sub-peduncle 7,c71 whilst still bearing from thirty to forty flower-buds1 sometimes becomes a little elongated and partially assumes all the characters of the corresponding branch of a true tendril4 ,from this state we can trace every stage till we come to a full-sized perfect tendril1 bearing on the branch which corresponds with the sub-peduncle one single flower-bud6 ,hence there can be no doubt that the tendril is a modified flower-peduncle4 ,another kind of gradation well deserves notice4 ,flower-tendrils 7,b1 fig4 #aj7 sometimes produce a few flower-buds4 ,for instance1 on a vine growing against my house1 there were thirteen and twenty-two flower-buds respectively on two flower-tendrils1 which still retained their characteristic qualities of sensitiveness and spontaneous movement1 but in a somewhat lessened degree4 ,on vines in hothouses1 so many flowers are occasionally produced on the flower-tendrils that a double bunch of grapes is the result2 and this is technically called by gardeners a 8cluster40 ,in this state the whole bunch of flowers presents scarcely any resemblance to a tendril2 and1 judging from the facts already given1 it would probably possess little power of clasping a support1 or of spontaneous movement4 ,such flower-stalks closely resemble in structure those borne by ,cissus4 ,this genus1 belonging to the same family of the ,vitace1 produces well-developed tendrils and ordinary bunches of flowers2 but there are no gradations between the two states4 ,if the genus ,vitis had been unknown1 the boldest believer in the modification of species would never have surmised that the same individual plant1 at the same period of growth1 would have yielded every possible gradation between ordinary flower-stalks for the support of the flowers and fruit1 and tendrils used exclusively for climbing4 ,but the vine clearly gives us such a case2 and it seems to me as striking and curious an instance of transition as can well be conceived4 ,cissus discolor4--,the young shoots show no more movement than can be accounted for by daily variations in the action of the light4 ,the tendrils1 however1 revolve with much regularity1 following the sun2 and1 in the plants observed by me1 swept circles of about #e inches in diameter4 ,five circles were completed in the following times3--#d hrs4 #de m41 #d hrs4 #ej m41 #d hrs4 #de m41 #d hrs4 #cj m41 and #e hrs4 ,the same tendril continues to revolve during three or four days4 ,the tendrils are from #c to #e inches in length4 ,they are formed of a long foot-stalk1 bearing two short branches1 which in old plants again bifurcate4 ,the two branches are not of quite equal length2 and as with the vine1 the longer one has a scale at its base4 ,the tendril stands vertically upwards2 the extremity of the shoot being bent abruptly downwards1 and this position is probably of service to the plant by allowing the tendril to revolve freely and vertically4 ,both branches of the tendril1 whilst young1 are highly sensitive4 ,a touch with a pencil1 so gentle as only just to move a tendril borne at the end of a long flexible shoot1 sufficed to cause it to become perceptibly curved in four or five minutes4 ,it became straight again in rather above one hour4 ,a loop of soft thread weighing one-seventh of a grain 7#i4be mg47 was thrice tried1 and each time caused the tendril to become curved in #cj or #dj m4 ,half this weight produced no effect4 ,the long foot-stalk is much less sensitive1 for a slight rubbing produced no effect1 although prolonged contact with a stick caused it to bend4 ,the two branches are sensitive on all sides1 so that they converge if touched on their inner sides1 and diverge if touched on their outer sides4 ,if a branch be touched at the same time with equal force on opposite sides1 both sides are equally stimulated and there is no movement4 ,before examining this plant1 ,i had observed only tendrils which are sensitive on one side alone1 and these when lightly pressed between the finger and thumb become curved2 but on thus pinching many times the tendrils of the ,cissus no curvature ensued1 and ,i falsely inferred at first that they were not at all sensitive4 ,cissus antarcticus4--,the tendrils on a young plant were thick and straight1 with the tips a little curved4 ,when their concave surfaces were rubbed1 and it was necessary to do this with some force1 they very slowly became curved1 and subsequently straight again4 ,they are therefore much less sensitive than those of the last species2 but they made two revolutions1 following the sun1 rather more rapidly1 viz41 in #c hrs4 #cj m4 and #d hrs4 ,the internodes do not revolve4 ,ampelopsis hederacea 7,virginian ,creeper74--,the internodes apparently do not move more than can be accounted for by the varying action of the light4 ,the tendrils are from #d to #e inches in length1 with the main stem sending off several lateral branches1 which have their tips curved1 as may be seen in the upper figure 7fig4 #aa74 ,they exhibit no true spontaneous revolving movement1 but turn1 as was long ago observed by ,andrew ,knight1 #ade from the light to the dark4 ,i have seen several tendrils move in less than #bd hours1 through an angle of #ahj to the dark side of a case in which a plant was placed1 but the movement is sometimes much slower4 ,the several lateral branches often move independently of one another1 and sometimes irregularly1 without any apparent cause4 ,these tendrils are less sensitive to a touch than any others observed by me4 ,by gentle but repeated rubbing with a twig1 the lateral branches1 but not the main stem1 became in the course of three or four hours slightly curved2 but they seemed to have hardly any power of again straightening themselves4 ,the tendrils of a plant which had crawled over a large box-tree clasped several of the branches2 but ,i have repeatedly seen that they will withdraw themselves after seizing a stick4 ,when they meet with a flat surface of wood or a wall 7and this is evidently what they are adapted for71 they turn all their branches towards it1 and1 spreading them widely apart1 bring their hooked tips laterally into contact with it4 ,in effecting this1 the several branches1 after touching the surface1 often rise up1 place themselves in a new position1 and again come down into contact with it4 ,in the course of about two days after a tendril has arranged its branches so as to press on any surface1 the curved tips swell1 become bright red1 and form on their under-sides the well-known little discs or cushions with which they adhere firmly4 ,in one case the tips were slightly swollen in #ch hrs4 after coming into contact with a brick2 in another case they were considerably swollen in #dh hrs41 and in an additional #bd hrs4 were firmly attached to a smooth board2 and lastly1 the tips of a younger tendril not only swelled but became attached to a stuccoed wall in #db hrs4 ,these adhesive discs resemble1 except in colour and in being larger1 those of ,bignonia capreolata4 ,when they were developed in contact with a ball of tow1 the fibres were separately enveloped1 but not in so effective a manner as by ,b4 capreolata4 ,discs are never developed1 as far as ,i have seen1 without the stimulus of at least temporary contact with some object4 #adf ,they are generally first formed on one side of the curved tip1 the whole of which often becomes so much changed in appearance1 that a line of the original green tissue can be traced only along the concave surface4 ,when1 however1 a tendril has clasped a cylindrical stick1 an irregular rim or disc is sometimes formed along the inner surface at some little distance from the curved tip2 this was also observed 7p4 #ga7 by ,mohl4 ,the discs consist of enlarged cells1 with smooth projecting hemispherical surfaces1 coloured red2 they are at first gorged with fluid 7see section given by ,mohl1 p4 #gj71 but ultimately become woody4 ,as the discs soon adhere firmly to such smooth surfaces as planed or painted wood1 or to the polished leaf of the ivy1 this alone renders it probable that some cement is secreted1 as has been asserted to be the case 7quoted by ,mohl1 p4 #ga7 by ,malpighi4 ,i removed a number of discs formed during the previous year from a stuccoed wall1 and left them during many hours1 in warm water1 diluted acetic acid and alcohol2 but the attached grains of silex were not loosened4 ,immersion in sulphuric ether for #bd hrs4 loosened them much1 but warmed essential oils 7,i tried oil of thyme and peppermint7 completely released every particle of stone in the course of a few hours4 ,this seems to prove that some resinous cement is secreted4 ,the quantity1 however1 must be small2 for when a plant ascended a thinly whitewashed wall1 the discs adhered firmly to the whitewash2 but as the cement never penetrated the thin layer1 they were easily withdrawn1 together with little scales of the whitewash4 ,it must not be supposed that the attachment is effected exclusively by the cement2 for the cellular outgrowth completely envelopes every minute and irregular projection1 and insinuates itself into every crevice4 ,picture3 ,fig4 #aa4 ,ampelopsis hederacea4 ,a4 ,tendril fully developed1 with a young leaf on the opposite side of the stem4 ,b4 ,older tendril1 several weeks after its attachment to a wall1 with the branches thickened and spirally contracted1 and with the extremities developed into discs4 ,the unattached branches of this tendril have withered and dropped off ,a tendril which has not become attached to any body1 does not contract spirally2 and in course of a week or two shrinks into the finest thread1 withers and drops off4 ,an attached tendril1 on the other hand1 contracts spirally1 and thus becomes highly elastic1 so that when the main foot-stalk is pulled the strain is distributed equally between all the attached discs4 ,for a few days after the attachment of the discs1 the tendril remains weak and brittle1 but it rapidly increases in thickness and acquires great strength4 ,during the following winter it ceases to live1 but adheres firmly in a dead state both to its own stem and to the surface of attachment4 ,in the accompanying diagram 7fig4 #aa47 we see the difference between a tendril 7,b7 some weeks after its attachment to a wall1 with one 7,a7 from the same plant fully grown but unattached4 ,that the change in the nature of the tissues1 as well as the spiral contraction1 are consequent on the formation of the discs1 is well shown by any lateral branches which have not become attached2 for these in a week or two wither and drop off1 in the same manner as does the whole tendril if unattached4 ,the gain in strength and durability in a tendril after its attachment is something wonderful4 ,there are tendrils now adhering to my house which are still strong1 and have been exposed to the weather in a dead state for fourteen or fifteen years4 ,one single lateral branchlet of a tendril1 estimated to be at least ten years old1 was still elastic and supported a weight of exactly two pounds4 ,the whole tendril had five disc-bearing branches of equal thickness and apparently of equal strength2 so that after having been exposed during ten years to the weather1 it would probably have resisted a strain of ten pounds6 ,,sapindace4--,cardiospermum halicacabum4--,in this family1 as in the last1 the tendrils are modified flower-peduncles4 ,in the present plant the two lateral branches of the main flower-peduncle have been converted into a pair of tendrils1 corresponding with the single 8flower-tendril0 of the common vine4 ,the main peduncle is thin1 stiff1 and from #c to #d inches in length4 ,near the summit1 above two little bracts1 it divides into three branches4 ,the middle one divides and re-divides1 and bears the flowers2 ultimately it grows half as long again as the two other modified branches4 ,these latter are the tendrils2 they are at first thicker and longer than the middle branch1 but never become more than an inch in length4 ,they taper to a point and are flattened1 with the lower clasping surface destitute of hairs4 ,at first they project straight up2 but soon diverging1 spontaneously curl downwards so as to become symmetrically and elegantly hooked1 as represented in the diagram4 ,they are now1 whilst the flower-buds are still small1 ready for action4 ,picture3 ,fig4 #ab4 ,cardiospermum halicacabum4 ,upper part of the flower-peduncle with its two tendrils ,the two or three upper internodes1 whilst young1 steadily revolve2 those on one plant made two circles1 against the course of the sun1 in #c hrs4 #ab m42 in a second plant the same course was followed1 and the two circles were completed in #c hrs4 #da m42 in a third plant1 the internodes followed the sun and made two circles in #c hrs4 #dg m4 ,the average rate of these six revolutions was #a hr4 #df m4 ,the stem shows no tendency to twine spirally round a support2 but the allied tendril-bearing genus ,paullinia is said 7,mohl1 p4 #d7 to be a twiner4 ,the flower-peduncles1 which stand up above the end of the shoot1 are carried round and round by the revolving movement of the internodes2 and when the stem is securely tied1 the long and thin flower-peduncles themselves are seen to be in continued and sometimes rapid movement from side to side4 ,they sweep a wide space1 but only occasionally revolve in a regular elliptical course4 ,by the combined movements of the internodes and peduncles1 one of the two short hooked tendrils1 sooner or later1 catches hold of some twig or branch1 and then it curls round and securely grasps it4 ,these tendrils are1 however1 but slightly sensitive2 for by rubbing their under surface only a slight movement is slowly produced4 ,i hooked a tendril on to a twig2 and in #a hr4 #de m4 it was curved considerably inwards2 in #b hrs4 #cj m4 it formed a ring2 and in from #e to #f hours from being first hooked1 it closely grasped the stick4 ,a second tendril acted at nearly the same rate2 but ,i observed one that took #bd hours before it curled twice round a thin twig4 ,tendrils which have caught nothing1 spontaneously curl up to a close helix after the interval of several days4 ,those which have curled round some object1 soon become a little thicker and tougher4 ,the long and thin main peduncle1 though spontaneously moving1 is not sensitive and never clasps a support4 ,nor does it ever contract spirally1 #aeb although a contraction of this kind apparently would have been of service to the plant in climbing4 ,nevertheless it climbs pretty well without this aid4 ,the seed-capsules though light1 are of enormous size 7hence its ,english name of balloon-vine71 and as two or three are carried on the same peduncle1 the tendrils rising close to them may be of service in preventing their being dashed to pieces by the wind4 ,in the hothouse the tendrils served simply for climbing4 ,the position of the tendrils alone suffices to show their homological nature4 ,in two instances one of two tendrils produced a flower at its tip2 this1 however1 did not prevent its acting properly and curling round a twig4 ,in a third case both lateral branches which ought to have been modified into tendrils1 produced flowers like the central branch1 and had quite lost their tendril-structure4 ,i have seen1 but was not enabled carefully to observe1 only one other climbing ,sapindaceous plant1 namely1 ,paullinia4 ,it was not in flower1 yet bore long forked tendrils4 ,so that1 ,paullinia1 with respect to its tendrils1 appears to bear the same relation to ,cardiospermum that ,cissus does to ,vitis4 ,,passiflorace4--,after reading the discussion and facts given by ,mohl 7p4 #dg7 on the nature of the tendrils in this family1 no one can doubt that they are modified flower-peduncles4 ,the tendrils and the flower-peduncles rise close side by side2 and my son1 ,william ,e4 ,darwin1 made sketches for me of their earliest state of development in the hybrid ,p4 floribunda4 ,the two organs appear at first as a single papilla which gradually divides2 so that the tendril appears to be a modified branch of the flower-peduncle4 ,my son found one very young tendril surmounted by traces of floral organs1 exactly like those on the summit of the true flower-peduncle at the same early age4 ,passiflora gracilis4--,this well-named1 elegant1 annual species differs from the other members of the group observed by me1 in the young internodes having the power of revolving4 ,it exceeds all the other climbing plants which ,i have examined1 in the rapidity of its movements1 and all tendril-bearers in the sensitiveness of the tendrils4 ,the internode which carries the upper active tendril and which likewise carries one or two younger immature internodes1 made three revolutions1 following the sun1 at an average rate of #a hr4 #d m42 it then made1 the day becoming very hot1 three other revolutions at an average rate of between #eg and #eh m42 so that the average of all six revolutions was #a hr4 #a m4 ,the apex of the tendril describes elongated ellipses1 sometimes narrow and sometimes broad1 with their longer axes inclined in slightly different directions4 ,the plant can ascend a thin upright stick by the aid of its tendrils2 but the stem is too stiff for it to twine spirally round it1 even when not interfered with by the tendrils1 these having been successively pinched off at an early age4 ,when the stem is secured1 the tendrils are seen to revolve in nearly the same manner and at the same rate as the internodes4 #aed ,the tendrils are very thin1 delicate1 and straight1 with the exception of the tips1 which are a little curved2 they are from #g to #i inches in length4 ,a half-grown tendril is not sensitive2 but when nearly full-grown they are extremely sensitive4 ,a single delicate touch on the concave surface of the tip soon caused one to curve2 and in #b minutes it formed an open helix4 ,a loop of soft thread weighing one thirty-second of a grain 7#b4jb mg47 placed most gently on the tip1 thrice caused distinct curvature4 ,a bent bit of thin platina wire weighing only fiftieth of a grain 7#a4bc mg47 twice produced the same effect2 but this latter weight1 when left suspended1 did not suffice to cause a permanent curvature4 ,these trials were made under a bell-glass1 so that the loops of thread and wire were not agitated by the wind4 ,the movement after a touch is very rapid3 ,i took hold of the lower part of several tendrils1 and then touched their concave tips with a thin twig and watched them carefully through a lens2 the tips evidently began to bend after the following intervals--#ca1 #be1 #cb1 #ca1 #bh1 #ci1 #ca1 and #cj seconds2 so that the movement was generally perceptible in half a minute after a touch2 but on one occasion it was distinctly visible in #be seconds4 ,one of the tendrils which thus became bent in #ca seconds1 had been touched two hours previously and had coiled into a helix2 so that in this interval it had straightened itself and had perfectly recovered its irritability4 ,to ascertain how often the same tendril would become curved when touched1 ,i kept a plant in my study1 which from being cooler than the hot-house was not very favourable for the experiment4 ,the extremity was gently rubbed four or five times with a thin stick1 and this was done as often as it was observed to have become nearly straight again after having been in action2 and in the course of #ed hrs4 it answered to the stimulus #ba times1 becoming each time hooked or spiral4 ,on the last occasion1 however1 the movement was very slight1 and soon afterwards permanent spiral contraction commenced4 ,no trials were made during the night1 so that the tendril would perhaps have answered a greater number of times to the stimulus2 though1 on the other hand1 from having no rest it might have become exhausted from so many quickly repeated efforts4 ,i repeated the experiment made on the ,echinocystis1 and placed several plants of this ,passiflora so close together1 that their tendrils were repeatedly dragged over each other2 but no curvature ensued4 ,i likewise repeatedly flirted small drops of water from a brush on many tendrils1 and syringed others so violently that the whole tendril was dashed about1 but they never became curved4 ,the impact from the drops of water was felt far more distinctly on my hand than that from the loops of thread 7weighing one thirty-second of a grain7 when allowed to fall on it from a height1 and these loops1 which caused the tendrils to become curved1 had been placed most gently on them4 ,hence it is clear1 that the tendrils either have become habituated to the touch of other tendrils and drops of rain1 or that they were from the first rendered sensitive only to prolonged though excessively slight pressure of solid objects1 with the exclusion of that from other tendrils4 ,to show the difference in the kind of sensitiveness in different plants and likewise to show the force of the syringe used1 ,i may add that the lightest jet from it instantly caused the leaves of a ,mimosa to close2 whereas the loop of thread weighing one thirty-second of a grain1 when rolled into a ball and placed gently on the glands at the bases of the leaflets of the ,mimosa1 caused no action4 ,passiflora punctata4--,the internodes do not move1 but the tendrils revolve regularly4 ,a half-grown and very sensitive tendril made three revolutions1 opposed to the course of the sun1 in #c hrs4 #e m41 #b hrs4 #dj m4 and #b hrs4 #ej m42 perhaps it might have travelled more quickly when nearly full-grown4 ,a plant was placed in front of a window1 and1 as with twining stems1 the light accelerated the movement of the tendril in one direction and retarded it in the other2 the semicircle towards the light being performed in one instance in #ae m4 less time and in a second instance in #bj m4 less time than that required by the semicircle towards the dark end of the room4 ,considering the extreme tenuity of these tendrils1 the action of the light on them is remarkable4 ,the tendrils are long1 and1 as just stated1 very thin1 with the tip slightly curved or hooked4 ,the concave side is extremely sensitive to a touch--even a single touch causing it to curl inwards2 it subsequently straightened itself1 and was again ready to act4 ,a loop of soft thread weighing one fourteenth of a grain 7#d4fbe mg47 caused the extreme tip to bend2 another time ,i tried to hang the same little loop on an inclined tendril1 but three times it slid off2 yet this extraordinarily slight degree of friction sufficed to make the tip curl4 ,the tendril1 though so sensitive1 does not move very quickly after a touch1 no conspicuous movement being observable until #e or #aj m4 had elapsed4 ,the convex side of the tip is not sensitive to a touch or to a suspended loop of thread4 ,on one occasion ,i observed a tendril revolving with the convex side of the tip forwards1 and in consequence it was not able to clasp a stick1 against which it scraped2 whereas tendrils revolving with the concave side forward1 promptly seize any object in their path4 ,passiflora quadrangularis4--,this is a very distinct species4 ,the tendrils are thick1 long1 and stiff2 they are sensitive to a touch only on the concave surface towards the extremity4 ,when a stick was placed so that the middle of the tendril came into contact with it1 no curvature ensued4 ,in the hothouse a tendril made two revolutions1 each in #b hrs4 #bb m42 in a cool room one was completed in #c hrs41 and a second in #d hrs4 ,the internodes do not revolve2 nor do those of the hybrid ,p4 floribunda4 ,tacsonia manicata4--,here again the internodes do not revolve4 ,the tendrils are moderately thin and long2 one made a narrow ellipse in #e hrs4 #bj m41 and the next day a broad ellipse in #e hrs4 #g m4 ,the extremity being lightly rubbed on the concave surface1 became just perceptibly curved in #g m41 distinctly in #aj m41 and hooked in #bj m4 ,we have seen that the tendrils in the last three families1 namely1 the ,vitace1 ,sapindace and ,passiflorace1 are modified flower-peduncles4 ,this is likewise the case1 according to ,de ,candolle 7as quoted by ,mohl71 with the tendrils of ,brunnichia1 one of the ,polygonace4 ,in two or three species of ,modecca1 one of the ,papayace1 the tendrils1 as ,i hear from ,prof4 ,oliver1 occasionally bear flowers and fruit2 so that they are axial in their nature4 ,the ,spiral ,contraction of ,tendrils4 ,this movement1 which shortens the tendrils and renders them elastic1 commences in half a day1 or in a day or two after their extremities have caught some object4 ,there is no such movement in any leaf-climber1 with the exception of an occasional trace of it in the petioles of ,tropolum tricolorum4 ,on the other hand1 the tendrils of all tendril-bearing plants1 contract spirally after they have caught an object with the following exceptions4 ,firstly1 ,corydalis claviculata1 but then this plant might be called a leaf-climber4 ,secondly and thirdly1 ,bignonia unguis with its close allies1 and ,cardiospermum2 but their tendrils are so short that their contraction could hardly occur1 and would be quite superfluous4 ,fourthly1 ,smila aspera offers a more marked exception1 as its tendrils are moderately long4 ,the tendrils of ,dicentra1 whilst the plant is young1 are short and after attachment only become slightly flexuous2 in older plants they are longer and then they contract spirally4 ,i have seen no other exceptions to the rule that tendrils1 after clasping with their extremities a support1 undergo spiral contraction4 ,when1 however1 the tendril of a plant of which the stem is immovably fixed1 catches some fixed object1 it does not contract1 simply because it cannot2 this1 however1 rarely occurs4 ,in the common ,pea the lateral branches alone contract1 and not the central stem2 and with most plants1 such as the ,vine1 ,passiflora1 ,bryony1 the basal portion never forms a spire4 ,i have said that in ,corydalis claviculata the end of the leaf or tendril 7for this part may be indifferently so called7 does not contract into a spire4 ,the branchlets1 however1 after they have wound round thin twigs1 become deeply sinuous or zigzag4 ,moreover the whole end of the petiole or tendril1 if it seizes nothing1 bends after a time abruptly downwards and inwards1 showing that its outer surface has gone on growing after the inner surface has ceased to grow4 ,that growth is the chief cause of the spiral contraction of tendrils may be safely admitted1 as shown by the recent researches of ,h4 de ,vries4 ,i will1 however1 add one little fact in support of this conclusion4 ,if the short1 nearly straight portion of an attached tendril of ,passiflora gracilis1 7and1 as ,i believe1 of other tendrils17 between the opposed spires1 be examined1 it will be found to be transversely wrinkled in a conspicuous manner on the outside2 and this would naturally follow if the outer side had grown more than the inner side1 this part being at the same time forcibly prevented from becoming curved4 ,so again the whole outer surface of a spirally wound tendril becomes wrinkled if it be pulled straight4 ,nevertheless1 as the contraction travels from the extremity of a tendril1 after it has been stimulated by contact with a support1 down to the base1 ,i cannot avoid doubting1 from reasons presently to be given1 whether the whole effect ought to be attributed to growth4 ,an unattached tendril rolls itself up into a flat helix1 as in the case of ,cardiospermum1 if the contraction commences at the extremity and is quite regular2 but if the continued growth of the outer surface is a little lateral1 or if the process begins near the base1 the terminal portion cannot be rolled up within the basal portion1 and the tendril then forms a more or less open spire4 ,a similar result follows if the extremity has caught some object1 and is thus held fast4 ,the tendrils of many kinds of plants1 if they catch nothing1 contract after an interval of several days or weeks into a spire2 but in these cases the movement takes place after the tendril has lost its revolving power and hangs down2 it has also then partly or wholly lost its sensibility2 so that this movement can be of no use4 ,the spiral contraction of unattached tendrils is a much slower process than that of attached ones4 ,young tendrils which have caught a support and are spirally contracted1 may constantly be seen on the same stem with the much older unattached and uncontracted tendrils4 ,in the ,echinocystis ,i have seen a tendril with the two lateral branches encircling twigs and contracted into beautiful spires1 whilst the main branch which had caught nothing remained for many days straight4 ,in this plant ,i once observed a main branch after it had caught a stick become spirally flexuous in #g hrs41 and spirally contracted in #ah hrs4 ,generally the tendrils of the ,echinocystis begin to contract in from #ab hrs4 to #bd hrs4 after catching some object2 whilst unattached tendrils do not begin to contract until two or three or even more days after all revolving movement has ceased4 ,a full-grown tendril of ,passiflora quadrangularis which had caught a stick began in #h hrs4 to contract1 and in #bd hrs4 formed several spires2 a younger tendril1 only two-thirds grown1 showed the first trace of contraction in two days after clasping a stick1 and in two more days formed several spires4 ,it appears1 therefore1 that the contraction does not begin until the tendril is grown to nearly its full length4 ,another young tendril of about the same age and length as the last did not catch any object2 it acquired its full length in four days2 in six additional days it first became flexuous1 and in two more days formed one complete spire4 ,this first spire was formed towards the basal end1 and the contraction steadily but slowly progressed towards the apex2 but the whole was not closely wound up into a spire until #ba days had elapsed from the first observation1 that is1 until #ag days after the tendril had grown to its full length4 ,the spiral contraction of tendrils is quite independent of their power of spontaneously revolving1 for it occurs in tendrils1 such as those of ,lathyrus grandiflorus and ,ampelopsis hederacea1 which do not revolve4 ,it is not necessarily related to the curling of the tips round a support1 as we see with the ,ampelopsis and ,bignonia capreolata1 in which the development of adherent discs suffices to cause spiral contraction4 ,yet in some cases this contraction seems connected with the curling or clasping movement1 due to contact with a support2 for not only does it soon follow this act1 but the contraction generally begins close to the curled extremity1 and travels downwards to the base4 ,if1 however1 a tendril be very slack1 the whole length almost simultaneously becomes at first flexuous and then spiral4 ,again1 the tendrils of some few plants never contract spirally unless they have first seized hold of some object2 if they catch nothing they hang down1 remaining straight1 until they wither and drop off3 this is the case with the tendrils of ,bignonia1 which consist of modified leaves1 and with those of three genera of the ,vitace1 which are modified flower-peduncles4 ,but in the great majority of cases1 tendrils which have never come in contact with any object1 after a time contract spirally4 ,all these facts taken together1 show that the act of clasping a support and the spiral contraction of the whole length of the tendril1 are phenomena not necessarily connected4 ,the spiral contraction which ensues after a tendril has caught a support is of high service to the plant2 hence its almost universal occurrence with species belonging to widely different orders4 ,when a shoot is inclined and its tendril has caught an object above1 the spiral contraction drags up the shoot4 ,when the shoot is upright1 the growth of the stem1 after the tendrils have seized some object above1 would leave it slack1 were it not for the spiral contraction which draws up the stem as it increases in length4 ,thus there is no waste of growth1 and the stretched stem ascends by the shortest course4 ,when a terminal branchlet of the tendril of ,coba catches a stick1 we have seen how well the spiral contraction successively brings the other branchlets1 one after the other1 into contact with the stick1 until the whole tendril grasps it in an inextricable knot4 ,when a tendril has caught a yielding object1 this is sometimes enveloped and still further secured by the spiral folds1 as ,i have seen with ,passiflora quadrangularis2 but this action is of little importance4 ,a far more important service rendered by the spiral contraction of the tendrils is that they are thus made highly elastic4 ,as before remarked under ,ampelopsis1 the strain is thus distributed equally between the several attached branches2 and this renders the whole far stronger than it otherwise would be1 as the branches cannot break separately4 ,it is this elasticity which protects both branched and simple tendrils from being torn away from their supports during stormy weather4 ,i have more than once gone on purpose during a gale to watch a ,bryony growing in an exposed hedge1 with its tendrils attached to the surrounding bushes2 and as the thick and thin branches were tossed to and fro by the wind1 the tendrils1 had they not been excessively elastic1 would instantly have been torn off and the plant thrown prostrate4 ,but as it was1 the ,bryony safely rode out the gale1 like a ship with two anchors down1 and with a long range of cable ahead to serve as a spring as she surges to the storm4 ,when an unattached tendril contracts spirally1 the spire always runs in the same direction from tip to base4 ,a tendril1 on the other hand1 which has caught a support by its extremity1 although the same side is concave from end to end1 invariably becomes twisted in one part in one direction1 and in another part in the opposite direction2 the oppositely turned spires being separated by a short straight portion4 ,this curious and symmetrical structure has been noticed by several botanists1 but has not been sufficiently explained4 #afe ,it occurs without exception with all tendrils which after catching an object contract spirally1 but is of course most conspicuous in the longer tendrils4 ,it never occurs with uncaught tendrils2 and when this appears to have occurred1 it will be found that the tendril had originally seized some object and had afterwards been torn free4 ,commonly1 all the spires at one end of an attached tendril run in one direction1 and all those at the other end in the opposite direction1 with a single short straight portion in the middle2 but ,i have seen a tendril with the spires alternately turning five times in opposite directions1 with straight pieces between them2 and ,m4 ,lon has seen seven or eight such alternations4 ,whether the spires turn once or more than once in opposite directions1 there are as many turns in the one direction as in the other4 ,for instance1 ,i gathered ten attached tendrils of the ,bryony1 the longest with #cc1 and the shortest with only #h spiral turns2 and the number of turns in the one direction was in every case the same 7within one7 as in the opposite direction4 ,picture3 ,fig4 #ac4 ,a caught tendril of ,bryonia dioica1 spirally contracted in reserved directions ,the explanation of this curious little fact is not difficult4 ,i will not attempt any geometrical reasoning1 but will give only a practical illustration4 ,in doing this1 ,i shall first have to allude to a point which was almost passed over when treating of ,twining-plants4 ,if we hold in our left hand a bundle of parallel strings1 we can with our right hand turn these round and round1 thus imitating the revolving movement of a twining plant1 and the strings do not become twisted4 ,but if we hold at the same time a stick in our left hand1 in such a position that the strings become spirally turned round it1 they will inevitably become twisted4 ,hence a straight coloured line1 painted along the internodes of a twining plant before it has wound round a support1 becomes twisted or spiral after it has wound round4 ,i painted a red line on the straight internodes of a ,humulus1 ,mikania1 ,ceropegia1 ,convolvulus1 and ,phaseolus1 and saw it become twisted as the plant wound round a stick4 ,it is possible that the stems of some plants by spontaneously turning on their own axes1 at the proper rate and in the proper direction1 might avoid becoming twisted2 but ,i have seen no such case4 ,in the above illustration1 the parallel strings were wound round a stick2 but this is by no means necessary1 for if wound into a hollow coil 7as can be done with a narrow slip of elastic paper7 there is the same inevitable twisting of the axis4 ,when1 therefore1 a free tendril coils itself into a spire1 it must either become twisted along its whole length 7and this never occurs71 or the free extremity must turn round as many times as there are spires formed4 ,it was hardly necessary to observe this fact2 but ,i did so by affixing little paper vanes to the extreme points of the tendrils of ,echinocystis and ,passiflora quadrangularis2 and as the tendril contracted itself into successive spires1 the vane slowly revolved4 ,we can now understand the meaning of the spires being invariably turned in opposite directions1 in tendrils which from having caught some object are fixed at both ends4 ,let us suppose a caught tendril to make thirty spiral turns all in the same direction2 the inevitable result would be that it would become twisted thirty times on its own axis4 ,this twisting would not only require considerable force1 but1 as ,i know by trial1 would burst the tendril before the thirty turns were completed4 ,such cases never really occur2 for1 as already stated1 when a tendril has caught a support and is spirally contracted1 there are always as many turns in one direction as in the other2 so that the twisting of the axis in the one direction is exactly compensated by the twisting in the opposite direction4 ,we can further see how the tendency is given to make the later formed coils opposite to those1 whether turned to the right or to the left1 which are first made4 ,take a piece of string1 and let it hang down with the lower end fixed to the floor2 then wind the upper end 7holding the string quite loosely7 spirally round a perpendicular pencil1 and this will twist the lower part of the string2 and after it has been sufficiently twisted1 it will be seen to curve itself into an open spire1 with the curves running in an opposite direction to those round the pencil1 and consequently with a straight piece of string between the opposed spires4 ,in short1 we have given to the string the regular spiral arrangement of a tendril caught at both ends4 ,the spiral contraction generally begins at the extremity which has clasped a support2 and these first-formed spires give a twist to the axis of the tendril1 which necessarily inclines the basal part into an opposite spiral curvature4 ,i cannot resist giving one other illustration1 though superfluous3 when a haberdasher winds up ribbon for a customer1 he does not wind it into a single coil2 for1 if he did1 the ribbon would twist itself as many times as there were coils2 but he winds it into a figure of eight on his thumb and little finger1 so that he alternately takes turns in opposite directions1 and thus the ribbon is not twisted4 ,so it is with tendrils1 with this sole difference1 that they take several consecutive turns in one direction and then the same number in an opposite direction2 but in both cases the self-twisting is avoided4 ,summary on the ,nature and ,action of ,tendrils4 ,with the majority of tendril-bearing plants the young internodes revolve in more or less broad ellipses1 like those made by twining plants2 but the figures described1 when carefully traced1 generally form irregular ellipsoidal spires4 ,the rate of revolution varies from one to five hours in different species1 and consequently is in some cases more rapid than with any twining plant1 and is never so slow as with those many twiners which take more than five hours for each revolution4 ,the direction is variable even in the same individual plant4 ,in ,passiflora1 the internodes of only one species have the power of revolving4 ,the ,vine is the weakest revolver observed by me1 apparently exhibiting only a trace of a former power4 ,in the ,eccremocarpus the movement is interrupted by many long pauses4 ,very few tendril-bearing plants can spirally twine up an upright stick4 ,although the power of twining has generally been lost1 either from the stiffness or shortness of the internodes1 from the size of the leaves1 or from some other unknown cause1 the revolving movement of the stem serves to bring the tendrils into contact with surrounding objects4 ,the tendrils themselves also spontaneously revolve4 ,the movement begins whilst the tendril is young1 and is at first slow4 ,the mature tendrils of ,bignonia littoralis move much slower than the internodes4 ,generally1 the internodes and tendrils revolve together at the same rate2 in ,cissus1 ,coba1 and most ,passiflor1 the tendrils alone revolve2 in other cases1 as with ,lathyrus aphaca1 only the internodes move1 carrying with them the motionless tendrils2 and1 lastly 7and this is the fourth possible case71 neither internodes nor tendrils spontaneously revolve1 as with ,lathyrus grandiflorus and ,ampelopsis4 ,in most ,bignonias1 ,eccremocarpus ,mutisia1 and the ,fumariace1 the internodes1 petioles and tendrils all move harmoniously together4 ,in every case the conditions of life must be favourable in order that the different parts should act in a perfect manner4 ,tendrils revolve by the curvature of their whole length1 excepting the sensitive extremity and the base1 which parts do not move1 or move but little4 ,the movement is of the same nature as that of the revolving internodes1 and1 from the observations of ,sachs and ,h4 de ,vries1 no doubt is due to the same cause1 namely1 the rapid growth of a longitudinal band1 which travels round the tendril and successively bows each part to the opposite side4 ,hence1 if a line be painted along that surface which happens at the time to be convex1 the line becomes first lateral1 then concave1 then lateral1 and ultimately again convex4 ,this experiment can be tried only on the thicker tendrils1 which are not affected by a thin crust of dried paint4 ,the extremities are often slightly curved or hooked1 and the curvature of this part is never reversed2 in this respect they differ from the extremities of twining shoots1 which not only reverse their curvature1 or at least become periodically straight1 but curve themselves in a greater degree than the lower part4 ,in most other respects a tendril acts as if it were one of several revolving internodes1 which all move together by successively bending to each point of the compass4 ,there is1 however1 in many cases this unimportant difference1 that the curving tendril is separated from the curving internode by a rigid petiole4 ,with most tendril-bearers the summit of the stem or shoot projects above the point from which the tendril arises2 and it is generally bent to one side1 so as to be out of the way of the revolutions swept by the tendril4 ,in those plants in which the terminal shoot is not sufficiently out of the way1 as we have seen with the ,echinocystis1 as soon as the tendril comes in its revolving course to this point1 it stiffens and straightens itself1 and thus rising vertically up passes over the obstacle in an admirable manner4 ,all tendrils are sensitive1 but in various degrees1 to contact with an object1 and curve towards the touched side4 ,with several plants a single touch1 so slight as only just to move the highly flexible tendril1 is enough to induce curvature4 ,passiflora gracilis possesses the most sensitive tendrils which ,i have observed3 a bit of platina wire #j4jb of a grain 7#a4bc mg47 in weight1 gently placed on the concave point1 caused a tendril to become hooked1 as did a loop of soft1 thin cotton thread weighing one thirty-second of a grain 7#b4jb mg47 ,with the tendrils of several other plants1 loops weighing one sixteenth of a grain 7#d4je mg47 sufficed4 ,the point of a tendril of ,passiflora gracilis began to move distinctly in #be seconds after a touch1 and in many cases after #cj seconds4 ,asa ,gray also saw movement in the tendrils of the ,cucurbitaceous genus1 ,sicyos1 in #cj seconds4 ,the tendrils of some other plants1 when lightly rubbed1 moved in a few minutes2 with ,dicentra in half-an-hour2 with ,smilax in an hour and a quarter or half2 and with ,ampelopsis still more slowly4 ,the curling movement consequent on a single touch continues to increase for a considerable time1 then ceases2 after a few hours the tendril uncurls itself1 and is again ready to act4 ,when the tendrils of several kinds of plants were caused to bend by extremely light weights suspended on them1 they seemed to grow accustomed to so slight a stimulus1 and straightened themselves1 as if the loops had been removed4 ,it makes no difference what sort of object a tendril touches1 with the remarkable exception of other tendrils and drops of water1 as was observed with the extremely sensitive-tendrils of ,passiflora gracilis and of the ,echinocystis4 ,i have1 however1 seen tendrils of the ,bryony which had temporarily caught other tendrils1 and often in the case of the vine4 ,tendrils of which the extremities are permanently and slightly curved1 are sensitive only on the concave surface2 other tendrils1 such as those of the ,coba 7though furnished with horny hooks directed to one side7 and those of ,cissus discolor1 are sensitive on all sides4 ,hence the tendrils of this latter plant1 when stimulated by a touch of equal force on opposite sides1 did not bend4 ,the inferior and lateral surfaces of the tendrils of ,mutisia are sensitive1 but not the upper surface4 ,with branched tendrils1 the several branches act alike2 but in the ,hanburya the lateral spur-like branch does not acquire 7for excellent reasons which have been explained7 its sensitiveness nearly so soon as the main branch4 ,with most tendrils the lower or basal part is either not at all sensitive1 or sensitive only to prolonged contact4 ,we thus see that the sensitiveness of tendrils is a special and localized capacity4 ,it is quite independent of the power of spontaneously revolving2 for the curling of the terminal portion from touch does not in the least interrupt the former movement4 ,in ,bignonia unguis and its close allies1 the petioles of the leaves1 as well as the tendrils1 are sensitive to a touch4 ,twining plants when they come into contact with a stick1 curl round it invariably in the direction of their revolving movement2 but tendrils curl indifferently to either side1 in accordance with the position of the stick and the side which is first touched4 ,the clasping movement of the extremity is apparently not steady1 but undulatory or vermicular in its nature1 as may be inferred from the curious manner in which the tendrils of the ,echinocystis slowly crawled round a smooth stick4 ,as with a few exceptions tendrils spontaneously revolve1 it may be asked1--why have they been endowed with sensitiveness8--why1 when they come into contact with a stick1 do they not1 like twining plants1 spirally wind round it8 ,one reason may be that they are in most cases so flexible and thin1 that when brought into contact with any object1 they would almost certainly yield and be dragged onwards by the revolving movement4 ,moreover1 the sensitive extremities have no revolving power as far as ,i have observed1 and could not by this means curl round a support4 ,with twining plants1 on the other hand1 the extremity spontaneously bends more than any other part2 and this is of high importance for the ascent of the plant1 as may be seen on a windy day4 ,it is1 however1 possible that the slow movement of the basal and stiffer parts of certain tendrils1 which wind round sticks placed in their path1 may be analogous to that of twining plants4 ,but ,i hardly attended sufficiently to this point1 and it would have been difficult to distinguish between a movement due to extremely dull irritability1 from the arrestment of the lower part1 whilst the upper part continued to move onwards4 ,tendrils which are only three-fourths grown1 and perhaps even at an earlier age1 but not whilst extremely young1 have the power of revolving and of grasping any object which they touch4 ,these two capacities are generally acquired at about the same period1 and both fail when the tendril is full grown4 ,but in ,coba and ,passiflora punctata the tendrils begin to revolve in a useless manner1 before they have become sensitive4 ,in the ,echinocystis they retain their sensitiveness for some time after they have ceased to revolve and after they have sunk downwards2 in this position1 even if they were able to seize an object1 such power would be of no service in supporting the stem4 ,it is a rare circumstance thus to detect any superfluity or imperfection in the action of tendrils--organs which are so excellently adapted for the functions which they have to perform2 but we see that they are not always perfect1 and it would be rash to assume that any existing tendril has reached the utmost limit of perfection4 ,some tendrils have their revolving motion accelerated or retarded1 in moving to or from the light2 others1 as with the ,pea1 seem indifferent to its action2 others move steadily from the light to the dark1 and this aids them in an important manner in finding a support4 ,for instance1 the tendrils of ,bignonia capreolata bend from the light to the dark as truly as a wind-vane from the wind4 ,in the ,eccremocarpus the extremities alone twist and turn about so as to bring their finer branches and hooks into close contact with any dark surface1 or into crevices and holes4 ,a short time after a tendril has caught a support1 it contracts with some rare exceptions into a spire2 but the manner of contraction and the several important advantages thus gained have been discussed so lately1 that nothing need here be repeated on the subject4 ,tendrils soon after catching a support grow much stronger and thicker1 and sometimes more durable to a wonderful degree2 and this shows how much their internal tissues must be changed4 ,occasionally it is the part which is wound round a support which chiefly becomes thicker and stronger2 ,i have seen1 for instance1 this part of a tendril of ,bignonia quinoctialis twice as thick and rigid as the free basal part4 ,tendrils which have caught nothing soon shrink and wither2 but in some species of ,bignonia they disarticulate and fall off like leaves in autumn4 99 99 99 99 99 ,any one who had not closely observed tendrils of many kinds would probably infer that their action was uniform4 ,this is the case with the simpler kinds1 which simply curl round an object of moderate thickness1 whatever its nature may be4 #agf ,but the genus ,bignonia shows us what diversity of action there may be between the tendrils of closely allied species4 ,in all the nine species observed by me1 the young internodes revolve vigorously2 the tendrils also revolve1 but in some of the species in a very feeble manner2 and lastly the petioles of nearly all revolve1 though with unequal power4 ,the petioles of three of the species1 and the tendrils of all are sensitive to contact4 ,in the first-described species1 the tendrils resemble in shape a bird's foot1 and they are of no service to the stem in spirally ascending a thin upright stick1 but they can seize firm hold of a twig or branch4 ,when the stem twines round a somewhat thick stick1 a slight degree of sensitiveness possessed by the petioles is brought into play1 and the whole leaf together with the tendril winds round it4 ,in ,b4 unguis the petioles are more sensitive1 and have greater power of movement than those of the last species2 they are able1 together with the tendrils1 to wind inextricably round a thin upright stick2 but the stem does not twine so well4 ,b4 ,tweedyana has similar powers1 but in addition1 emits arial roots which adhere to the wood4 ,in ,b4 venusta the tendrils are converted into elongated three-pronged grapnels1 which move spontaneously in a conspicuous manner2 the petioles1 however1 have lost their sensitiveness4 ,the stem of this species can twine round an upright stick1 and is aided in its ascent by the tendrils seizing the stick alternately some way above and then contracting spirally4 ,in ,b4 littoralis the tendrils1 petioles1 and internodes1 all revolve spontaneously4 ,the stem1 however1 cannot twine1 but ascends an upright stick by seizing it above with both tendrils together1 which then contract into a spire4 ,the tips of these tendrils become developed into adhesive discs4 ,b4 speciosa possesses similar powers of movement as the last species1 but it cannot twine round a stick1 though it can ascend by clasping the stick horizontally with one or both of its unbranched tendrils4 ,these tendrils continually insert their pointed ends into minute crevices or holes1 but as they are always withdrawn by the subsequent spiral contraction1 the habit seems to us in our ignorance useless4 ,lastly1 the stem of ,b4 capreolata twines imperfectly2 the much-branched tendrils revolve in a capricious manner1 and bend from the light to the dark2 their hooked extremities1 even whilst immature1 crawl into crevices1 and1 when mature1 seize any thin projecting point2 in either case they develop adhesive discs1 and these have the power of enveloping the finest fibres4 ,in the allied ,eccremocarpus the internodes1 petioles1 and much-branched tendrils all spontaneously revolve together4 ,the tendrils do not as a whole turn from the light2 but their bluntly-hooked extremities arrange themselves neatly on any surface with which they come into contact1 apparently so as to avoid the light4 ,they act best when each branch seizes a few thin stems1 like the culms of a grass1 which they afterwards draw together into a solid bundle by the spiral contraction of all the branches4 ,in ,coba the finely-branched tendrils alone revolve2 the branches terminate in sharp1 hard1 double1 little hooks1 with both points directed to the same side2 and these turn by well-adapted movements to any object with which they come into contact4 ,the tips of the branches also crawl into dark crevices or holes4 ,the tendrils and internodes of ,ampelopsis have little or no power of revolving2 the tendrils are but little sensitive to contact2 their hooked extremities cannot seize thin objects2 they will not even clasp a stick1 unless in extreme need of a support2 but they turn from the light to the dark1 and1 spreading out their branches in contact with any nearly flat surface1 develop discs4 ,these adhere by the secretion of some cement to a wall1 or even to a polished surface2 and this is more than the discs of the ,bignonia capreolata can effect4 ,the rapid development of these adherent discs is one of the most remarkable peculiarities possessed by any tendrils4 ,we have seen that such discs are formed by two species of ,bignonia1 by ,ampelopsis1 and1 according to ,naudin1 #agi by the ,cucurbitaceous genus ,peponopsis adhrens4 ,in ,anguria the lower surface of the tendril1 after it has wound round a stick1 forms a coarsely cellular layer1 which closely fits the wood1 but is not adherent2 whilst in ,hanburya a similar layer is adherent4 ,the growth of these cellular out-growths depends1 7except in the case of the ,haplolophium and of one species of ,ampelopsis17 on the stimulus from contact4 ,it is a singular fact that three families1 so widely distinct as the ,bignoniace1 ,vitace1 and ,cucurbitace1 should possess species with tendrils having this remarkable power4 99 99 99 99 99 ,sachs attributes all the movements of tendrils to rapid growth on the side opposite to that which becomes concave4 ,these movements consist of revolving nutation1 the bending to and from the light1 and in opposition to gravity1 those caused by a touch1 and spiral contraction4 ,it is rash to differ from so great an authority1 but ,i cannot believe that one at least of these movements--curvature from a touch--is thus caused4 #ahj ,in the first place it may be remarked that the movement of nutation differs from that due to a touch1 in so far that in some cases the two powers are acquired by the same tendril at different periods of growth2 and the sensitive part of the tendril does not seem capable of nutation4 ,one of my chief reasons for doubting whether the curvature from a touch is the result of growth1 is the extraordinary rapidity of the movement4 ,i have seen the extremity of a tendril of ,passiflora gracilis1 after being touched1 distinctly bent in #be seconds1 and often in #cj seconds2 and so it is with the thicker tendril of ,sicyos4 ,it appears hardly credible that their outer surfaces could have actually grown in length1 which implies a permanent modification of structure1 in so short a time4 ,the growth1 moreover1 on this view must be considerable1 for if the touch has been at all rough the extremity is coiled in two or three minutes into a spire of several turns4 ,when the extreme tip of the tendril of ,echinocystis caught hold of a smooth stick1 it coiled itself in a few hours 7as described at p4 #acb7 twice or thrice round the stick1 apparently by an undulatory movement4 ,at first ,i attributed this movement to the growth of the outside2 black marks were therefore made1 and the interspaces measured1 but ,i could not thus detect any increase in length4 ,hence it seems probable in this case and in others1 that the curvature of the tendril from a touch depends on the contraction of the cells along the concave side4 ,sachs himself admits #aha that 8if the growth which takes place in the entire tendril at the time of contact with a support is small1 a considerable acceleration occurs on the convex surface1 but in general there is no elongation on the concave surface1 or there may even be a contraction2 in the case of a tendril of ,cucurbita this contraction amounted to nearly one-third of the original length40 ,in a subsequent passage ,sachs seems to feel some difficulty in accounting for this kind of contraction4 ,it must not however be supposed from the foregoing remarks that ,i entertain any doubt1 after reading ,de ,vries' observations1 about the outer and stretched surfaces of attached tendrils afterwards increasing in length by growth4 ,such increase seems to me quite compatible with the first movement being independent of growth4 ,why a delicate touch should cause one side of a tendril to contract we know as little as why1 on the view held by ,sachs1 it should lead to extraordinarily rapid growth of the opposite side4 ,the chief or sole reason for the belief that the curvature of a tendril when touched is due to rapid growth1 seems to be that tendrils lose their sensitiveness and power of movement after they have grown to their full length2 but this fact is intelligible1 if we bear in mind that all the functions of a tendril are adapted to drag up the terminal growing shoot towards the light4 ,of what use would it be1 if an old and full-grown tendril1 arising from the lower part of a shoot1 were to retain its power of clasping a support8 ,this would be of no use2 and we have seen with tendrils so many instances of close adaptation and of the economy of means1 that we may feel assured that they would acquire irritability and the power of clasping a support at the proper age--namely1 youth--and would not uselessly retain such power beyond the proper age4 ,,chapter ,v4 ,,hook ,,and ,,root-,,climbers4--,,concluding ,,remarks4 ,plants climbing by the aid of hooks1 or merely scrambling over other plants--,root-climbers1 adhesive matter secreted by the rootlets--,general conclusions with respect to climbing plants1 and the stages of their development4 ,hook-,climbers4--,in my introductory remarks1 ,i stated that1 besides the two first great classes of climbing plants1 namely1 those which twine round a support1 and those endowed with irritability enabling them to seize hold of objects by means of their petioles or tendrils1 there are two other classes1 hook-climbers and root-climbers4 ,many plants1 moreover1 as ,fritz ,mller has remarked1 #ahc climb or scramble up thickets in a still more simple fashion1 without any special aid1 excepting that their leading shoots are generally long and flexible4 ,it may1 however1 be suspected from what follows1 that these shoots in some cases tend to avoid the light4 ,the few hook-climbers which ,i have observed1 namely1 ,galium aparine1 ,rubus australis1 and some climbing ,roses1 exhibit no spontaneous revolving movement4 ,if they had possessed this power1 and had been capable of twining1 they would have been placed in the class of ,twiners2 for some twiners are furnished with spines or hooks1 which aid them in their ascent4 ,for instance1 the ,hop1 which is a twiner1 has reflexed hooks as large as those of the ,galium2 some other twiners have stiff reflexed hairs2 and ,dipladenia has a circle of blunt spines at the bases of its leaves4 ,i have seen only one tendril-bearing plant1 namely1 ,smilax aspera1 which is furnished with reflexed spines2 but this is the case with several branch-climbers in ,south ,brazil and ,ceylon2 and their branches graduate into true tendrils4 ,some few plants apparently depend solely on their hooks for climbing1 and yet do so efficiently1 as certain palms in the ,new and ,old ,worlds4 ,even some climbing ,roses will ascend the walls of a tall house1 if covered with a trellis4 ,how this is effected ,i know not2 for the young shoots of one such ,rose1 when placed in a pot in a window1 bent irregularly towards the light during the day and from the light during the night1 like the shoots of any common plant2 so that it is not easy to understand how they could have got under a trellis close to the wall4 #ahd ,root-climbers4--,a good many plants come under this class1 and are excellent climbers4 ,one of the most remarkable is the ,marcgravia umbellata1 the stem of which in the tropical forests of ,south ,america1 as ,i hear from ,mr4 ,spruce1 grows in a curiously flattened manner against the trunks of trees2 here and there it puts forth claspers 7roots71 which adhere to the trunk1 and1 if the latter be slender1 completely embrace it4 ,when this plant has climbed to the light1 it produces free branches with rounded stems1 clad with sharp-pointed leaves1 wonderfully different in appearance from those borne by the stem as long as it remains adherent4 ,this surprising difference in the leaves1 ,i have also observed in a plant of ,marcgravia dubia in my hothouse4 ,root-climbers1 as far as ,i have seen1 namely1 the ,ivy 7,hedera heli71 ,ficus repens1 and ,f4 barbatus1 have no power of movement1 not even from the light to the dark4 ,as previously stated1 the ,hoya carnosa 7,asclepiadace7 is a spiral twiner1 and likewise adheres by rootlets even to a flat wall4 ,the tendril-bearing ,bignonia ,tweedyana emits roots1 which curve half round and adhere to thin sticks4 ,the ,tecoma radicans 7,bignoniace71 which is closely allied to many spontaneously revolving species1 climbs by rootlets2 nevertheless1 its young shoots apparently move about more than can be accounted for by the varying action of the light4 ,i have not closely observed many root-climbers1 but can give one curious fact4 ,ficus repens climbs up a wall just like ,ivy2 and when the young rootlets are made to press lightly on slips of glass1 they emit after about a week's interval1 as ,i observed several times1 minute drops of clear fluid1 not in the least milky like that exuded from a wound4 ,this fluid is slightly viscid1 but cannot be drawn out into threads4 ,it has the remarkable property of not soon drying2 a drop1 about the size of half a pin's head1 was slightly spread out on glass1 and ,i scattered on it some minute grains of sand4 ,the glass was left exposed in a drawer during hot and dry weather1 and if the fluid had been water1 it would certainly have dried in a few minutes2 but it remained fluid1 closely surrounding each grain of sand1 during #abh days3 how much longer it would have remained ,i cannot say4 ,some other rootlets were left in contact with the glass for about ten days or a fortnight1 and the drops of secreted fluid were now rather larger1 and so viscid that they could be drawn out into threads4 ,some other rootlets were left in contact during twenty-three days1 and these were firmly cemented to the glass4 ,hence we may conclude that the rootlets first secrete a slightly viscid fluid1 subsequently absorb the watery parts1 7for we have seen that the fluid will not dry by itself17 and ultimately leave a cement4 ,when the rootlets were torn from the glass1 atoms of yellowish matter were left on it1 which were partly dissolved by a drop of bisulphide of carbon2 and this extremely volatile fluid was rendered very much less volatile by what it had dissolved4 ,as the bisulphide of carbon has a strong power of softening indurated caoutchouc1 ,i soaked in it during a short time several rootlets of a plant which had grown up a plaistered wall2 and ,i then found many extremely thin threads of transparent1 not viscid1 excessively elastic matter1 precisely like caoutchouc1 attached to two sets of rootlets on the same branch4 ,these threads proceeded from the bark of the rootlet at one end1 and at the other end were firmly attached to particles of silex or mortar from the wall4 ,there could be no mistake in this observation1 as ,i played with the threads for a long time under the microscope1 drawing them out with my dissecting-needles and letting them spring back again4 ,yet ,i looked repeatedly at other rootlets similarly treated1 and could never again discover these elastic threads4 ,i therefore infer that the branch in question must have been slightly moved from the wall at some critical period1 whilst the secretion was in the act of drying1 through the absorption of its watery parts4 ,the genus ,ficus abounds with caoutchouc1 and we may conclude from the facts just given that this substance1 at first in solution and ultimately modified into an unelastic cement1 #ahg is used by the ,ficus repens to cement its rootlets to any surface which it ascends4 ,whether other plants1 which climb by their rootlets1 emit any cement ,i do not know2 but the rootlets of the ,ivy1 placed against glass1 barely adhered to it1 yet secreted a little yellowish matter4 ,i may add1 that the rootlets of the ,marcgravia dubia can adhere firmly to smooth painted wood4 ,vanilla aromatica emits arial roots a foot in length1 which point straight down to the ground4 ,according to ,mohl 7p4 #di71 these crawl into crevices1 and when they meet with a thin support1 wind round it1 as do tendrils4 ,a plant which ,i kept was young1 and did not form long roots2 but on placing thin sticks in contact with them1 they certainly bent a little to that side1 in the course of about a day1 and adhered by their rootlets to the wood2 but they did not bend quite round the sticks1 and afterwards they re-pursued their downward course4 ,it is probable that these slight movements of the roots are due to the quicker growth of the side exposed to the light1 in comparison with the other side1 and not because the roots are sensitive to contact in the same manner as true tendrils4 ,according to ,mohl1 the rootlets of certain species of ,lycopodium act as tendrils4 #ahh ,concluding ,remarks on ,climbing ,plants4 ,plants become climbers1 in order1 as it may be presumed1 to reach the light1 and to expose a large surface of their leaves to its action and to that of the free air4 ,this is effected by climbers with wonderfully little expenditure of organized matter1 in comparison with trees1 which have to support a load of heavy branches by a massive trunk4 ,hence1 no doubt1 it arises that there are so many climbing plants in all quarters of the world1 belonging to so many different orders4 ,these plants have been arranged under four classes1 disregarding those which merely scramble over bushes without any special aid4 ,hook-climbers are the least efficient of all1 at least in our temperate countries1 and can climb only in the midst of an entangled mass of vegetation4 ,root-climbers are excellently adapted to ascend naked faces of rock or trunks of trees2 when1 however1 they climb trunks they are compelled to keep much in the shade2 they cannot pass from branch to branch and thus cover the whole summit of a tree1 for their rootlets require long-continued and close contact with a steady surface in order to adhere4 ,the two great classes of twiners and of plants with sensitive organs1 namely1 leaf-climbers and tendril-bearers taken together1 far exceed in number and in the perfection of their mechanism the climbers of the two first classes4 ,those which have the power of spontaneously revolving and of grasping objects with which they come in contact1 easily pass from branch to branch1 and securely ramble over a wide1 sun-lit surface4 ,the divisions containing twining plants1 leaf-climbers1 and tendril-bearers graduate to a certain extent into one another1 and nearly all have the same remarkable power of spontaneously revolving4 ,does this gradation1 it may be asked1 indicate that plants belonging to one subdivision have actually passed during the lapse of ages1 or can pass1 from one state to the other8 ,has1 for instance1 any tendril-bearing plant assumed its present structure without having previously existed as a leaf-climber or a twiner8 ,if we consider leaf-climbers alone1 the idea that they were primordially twiners is forcibly suggested4 ,the internodes of all1 without exception1 revolve in exactly the same manner as twiners2 some few can still twine well1 and many others in an imperfect manner4 ,several leaf-climbing genera are closely allied to other genera which are simple twiners4 ,it should also be observed1 that the possession of leaves with sensitive petioles1 and with the consequent power of clasping an object1 would be of comparatively little use to a plant1 unless associated with revolving internodes1 by which the leaves are brought into contact with a support2 although no doubt a scrambling plant would be apt1 as ,professor ,jaeger has remarked1 to rest on other plants by its leaves4 ,on the other hand1 revolving internodes1 without any other aid1 suffice to give the power of climbing2 so that it seems probable that leaf-climbers were in most cases at first twiners1 and subsequently became capable of grasping a support2 and this1 as we shall presently see1 is a great additional advantage4 ,from analogous reasons1 it is probable that all tendril-bearers were primordially twiners1 that is1 are the descendants of plants having this power and habit4 ,for the internodes of the majority revolve2 and1 in a few species1 the flexible stem still retains the capacity of spirally twining round an upright stick4 ,tendril-bearers have undergone much more modification than leaf-climbers2 hence it is not surprising that their supposed primordial habits of revolving and twining have been more frequently lost or modified than in the case of leaf-climbers4 ,the three great tendril-bearing families in which this loss has occurred in the most marked manner1 are the ,cucurbitace1 ,passiflorace1 and ,vitace4 ,in the first1 the internodes revolve2 but ,i have heard of no twining form1 with the exception 7according to ,palm1 p4 #bi4 #eb7 of ,momordica balsamina1 and this is only an imperfect twiner4 ,in the two other families ,i can hear of no twiners2 and the internodes rarely have the power of revolving1 this power being confined to the tendrils4 ,the internodes1 however1 of ,passiflora gracilis have the power in a perfect manner1 and those of the common ,vine in an imperfect degree3 so that at least a trace of the supposed primordial habit has been retained by some members of all the larger tendril-bearing groups4 ,on the view here given1 it may be asked1 ,why have the species which were aboriginally twiners been converted in so many groups into leaf-climbers or tendril-bearers8 ,of what advantage has this been to them8 ,why did they not remain simple twiners8 ,we can see several reasons4 ,it might be an advantage to a plant to acquire a thicker stem1 with short internodes bearing many or large leaves2 and such stems are ill fitted for twining4 ,any one who will look during windy weather at twining plants will see that they are easily blown from their support2 not so with tendril-bearers or leaf-climbers1 for they quickly and firmly grasp their support by a much more efficient kind of movement4 ,in those plants which still twine1 but at the same time possess tendrils or sensitive petioles1 as some species of ,bignonia1 ,clematis1 and ,tropolum1 it can readily be observed how incomparably better they grasp an upright stick than do simple twiners4 ,tendrils1 from possessing this power of grasping an object1 can be made long and thin2 so that little organic matter is expended in their development1 and yet they sweep a wide circle in search of a support4 ,tendril-bearers can1 from their first growth1 ascend along the outer branches of any neighbouring bush1 and they are thus always fully exposed to the light2 twiners1 on the contrary1 are best fitted to ascend bare stems1 and generally have to start in the shade4 ,within tall and dense tropical forests1 twining plants would probably succeed better than most kinds of tendril-bearers2 but the majority of twiners1 at least in our temperate regions1 from the nature of their revolving movement1 cannot ascend thick trunks1 whereas this can be affected by tendril-bearers if the trunks are branched or bear twigs1 and by some species if the bark is rugged4 ,the advantage gained by climbing is to reach the light and free air with as little expenditure of organic matter as possible2 now1 with twining plants1 the stem is much longer than is absolutely necessary2 for instance1 ,i measured the stem of a kidney-bean1 which had ascended exactly two feet in height1 and it was three feet in length3 the stem of a pea1 on the other hand1 which had ascended to the same height by the aid of its tendrils1 was but little longer than the height reached4 ,that this saving of the stem is really an advantage to climbing plants1 ,i infer from the species that still twine but are aided by clasping petioles or tendrils1 generally making more open spires than those made by simple twiners4 ,moreover1 the plants thus aided1 after taking one or two turns in one direction1 generally ascend for a space straight1 and then reverse the direction of their spire4 ,by this means they ascend to a considerably greater height1 with the same length of stem1 than would otherwise have been possible2 and they do this with safety1 as they secure themselves at intervals by their clasping petioles or tendrils4 ,we have seen that tendrils consist of various organs in a modified state1 namely1 leaves1 flower-peduncles1 branches1 and perhaps stipules4 ,with respect to leaves1 the evidence of their modification is ample4 ,in young plants of ,bignonia the lower leaves often remain quite unchanged1 whilst the upper ones have their terminal leaflets converted into perfect tendrils2 in ,eccremocarpus ,i have seen a single lateral branch of a tendril replaced by a perfect leaflet2 in ,vicia sativa1 on the other hand1 leaflets are sometimes replaced by tendril-branches2 and many other such cases could be given4 ,but he who believes in the slow modification of species will not be content simply to ascertain the homological nature of different kinds of tendrils2 he will wish to learn1 as far as is possible1 by what actual steps leaves1 flower-peduncles1 c41 have had their functions wholly changed1 and have come to serve merely as prehensile organs4 ,in the whole group of leaf-climbers abundant evidence has been given that an organ1 still subserving the functions of a leaf1 may become sensitive to a touch1 and thus grasp an adjoining object4 ,with several leaf-climbers the true leaves spontaneously revolve2 and their petioles1 after clasping a support grow thicker and stronger4 ,we thus see that leaves may acquire all the leading and characteristic qualities of tendrils1 namely1 sensitiveness1 spontaneous movement1 and subsequently increased strength4 ,if their blades or lamin were to abort1 they would form true tendrils4 ,and of this process of abortion we can follow every step1 until no trace of the original nature of the tendril is left4 ,in ,mutisia clematis1 the tendril1 in shape and colour1 closely resembles the petiole of one of the ordinary leaves1 together with the midribs of the leaflets1 but vestiges of the lamin are still occasionally retained4 ,in four genera of the ,fumariace we can follow the whole process of transformation4 ,the terminal leaflets of the leaf-climbing ,fumaria officinalis are not smaller than the other leaflets2 those of the leaf-climbing ,adlumia cirrhosa are greatly reduced2 those of ,corydalis claviculata 7a plant which may indifferently be called a leaf-climber or a tendril-bearer7 are either reduced to microscopical dimensions or have their blades wholly aborted1 so that this plant is actually in a state of transition2 and1 finally1 in the ,dicentra the tendrils are perfectly characterized4 ,if1 therefore1 we could behold at the same time all the progenitors of ,dicentra1 we should almost certainly see a series like that now exhibited by the above-named three genera4 ,in ,tropolum tricolorum we have another kind of passage2 for the leaves which are first formed on the young stems are entirely destitute of lamin1 and must be called tendrils1 whilst the later formed leaves have well-developed lamin4 ,in all cases the acquirement of sensitiveness by the mid-ribs of the leaves appears to stand in some close relation with the abortion of their lamin or blades4 ,on the view here given1 leaf-climbers were primordially twiners1 and tendril-bearers 7when formed of modified leaves7 were primordially leaf-climbers4 ,the latter1 therefore1 are intermediate in nature between twiners and tendril-bearers1 and ought to be related to both4 ,this is the case3 thus the several leaf-climbing species of the ,antirrhine1 of ,solanum1 ,cocculus1 and ,gloriosa1 have within the same family and even within the same genus1 relatives which are twiners4 ,in the genus ,mikania1 there are leaf-climbing and twining species4 ,the leaf-climbing species of ,clematis are very closely allied to the tendril-bearing ,naravelia4 ,the ,fumariace include closely allied genera which are leaf-climbers and tendril-bearers4 ,lastly1 a species of ,bignonia is at the same time both a leaf-climber and a tendril-bearer2 and other closely allied species are twiners4 ,tendrils of another kind consist of modified flower-peduncles4 ,in this case we likewise have many interesting transitional states4 ,the common ,vine 7not to mention the ,cardiospermum7 gives us every possible gradation between a perfectly developed tendril and a flower-peduncle covered with flowers1 yet furnished with a branch1 forming the flower-tendril4 ,when the latter itself bears a few flowers1 as we know sometimes is the case1 and still retains the power of clasping a support1 we see an early condition of all those tendrils which have been formed by the modification of flower-peduncles4 ,according to ,mohl and others1 some tendrils consist of modified branches3 ,i have not observed any such cases1 and know nothing of their transitional states1 but these have been fully described by ,fritz ,mller4 ,the genus ,lophospermum also shows us how such a transition is possible2 for its branches spontaneously revolve and are sensitive to contact4 ,hence1 if the leaves on some of the branches of the ,lophospermum were to abort1 these branches would be converted into true tendrils4 ,nor is there anything improbable in certain branches alone being thus modified1 whilst others remained unaltered2 for we have seen with certain varieties of ,phaseolus1 that some of the branches are thin1 flexible1 and twine1 whilst other branches on the same plant are stiff and have no such power4 ,if we inquire how a petiole1 a branch or flower-peduncle first became sensitive to a touch1 and acquired the power of bending towards the touched side1 we get no certain answer4 ,nevertheless an observation by ,hofmeister #aig well deserves attention1 namely1 that the shoots and leaves of all plants1 whilst young1 move after being shaken4 ,kerner also finds1 as we have seen1 that the flower-peduncles of a large number of plants1 if shaken or gently rubbed bend to this side4 ,and it is young petioles and tendrils1 whatever their homological nature may be1 which move on being touched4 ,it thus appears that climbing plants have utilized and perfected a widely distributed and incipient capacity1 which capacity1 as far as we can see1 is of no service to ordinary plants4 ,if we further inquire how the stems1 petioles1 tendrils1 and flower-peduncles of climbing plants first acquired their power of spontaneously revolving1 or1 to speak more accurately1 of successively bending to all points of the compass1 we are again silenced1 or at most can only remark that the power of moving1 both spontaneously and from various stimulants1 is far more common with plants1 than is generally supposed to be the case by those who have not attended to the subject4 ,i have given one remarkable instance1 namely that of the ,maurandia semperflorens1 the young flower-peduncles of which spontaneously revolve in very small circles1 and bend when gently rubbed to the touched side2 yet this plant certainly does not profit by these two feebly developed powers4 ,a rigorous examination of other young plants would probably show slight spontaneous movements in their stems1 petioles or peduncles1 as well as sensitiveness to a touch4 #aih ,we see at least that the ,maurandia might1 by a little augmentation of the powers which it already possesses1 come first to grasp a support by its flower-peduncles1 and then1 by the abortion of some of its flowers 7as with ,vitis or ,cardiospermum71 acquire perfect tendrils4 ,there is one other interesting point which deserves notice4 ,we have seen that some tendrils owe their origin to modified leaves1 and others to modified flower-peduncles2 so that some are foliar and others axial in their nature4 ,it might therefore have been expected that they would have presented some difference in function4 ,this is not the case4 ,on the contrary1 they present the most complete identity in their several characteristic powers4 ,tendrils of both kinds spontaneously revolve at about the same rate4 ,both1 when touched1 bend quickly to the touched side1 and afterwards recover themselves and are able to act again4 ,in both the sensitiveness is either confined to one side or extends all round the tendril4 ,both are either attracted or repelled by the light4 ,the latter property is seen in the foliar tendrils of ,bignonia capreolata and in the axial tendrils of ,ampelopsis4 ,the tips of the tendrils in these two plants become1 after contact1 enlarged into discs1 which are at first adhesive by the secretion of some cement4 ,tendrils of both kinds1 soon after grasping a support1 contract spirally2 they then increase greatly in thickness and strength4 ,when we add to these several points of identity the fact that the petiole of ,solanum jasminoides1 after it has clasped a support1 assumes one of the most characteristic features of the axis1 namely1 a closed ring of woody vessels1 we can hardly avoid asking1 whether the difference between foliar and axial organs can be of so fundamental a nature as is generally supposed8 #aii ,we have attempted to trace some of the stages in the genesis of climbing plants4 ,but1 during the endless fluctuations of the conditions of life to which all organic beings have been exposed1 it might be expected that some climbing plants would have lost the habit of climbing4 ,in the cases given of certain ,south ,african plants belonging to great twining families1 which in their native country never twine1 but reassume this habit when cultivated in ,england1 we have a case in point4 ,in the leaf-climbing ,clematis flammula1 and in the tendril-bearing ,vine1 we see no loss in the power of climbing1 but only a remnant of the revolving power which is indispensable to all twiners1 and is so common as well as so advantageous to most climbers4 ,in ,tecoma radicans1 one of the ,bignoniace1 we see a last and doubtful trace of the power of revolving4 ,with respect to the abortion of tendrils1 certain cultivated varieties of ,cucurbita pepo have1 according to ,naudin1 #bjj either quite lost these organs or bear semi-monstrous representatives of them4 ,in my limited experience1 ,i have met with only one apparent instance of their natural suppression1 namely1 in the common bean4 ,all the other species of ,vicia1 ,i believe1 bear tendrils2 but the bean is stiff enough to support its own stem1 and in this species1 at the end of the petiole1 where1 according to analogy1 a tendril ought to have existed1 a small pointed filament projects1 about a third of an inch in length1 and which is probably the rudiment of a tendril4 ,this may be the more safely inferred1 as in young and unhealthy specimens of other tendril-bearing plants similar rudiments may occasionally be observed4 ,in the bean these filaments are variable in shape1 as is so frequently the case with rudimentary organs2 they are either cylindrical1 or foliaceous1 or are deeply furrowed on the upper surface4 ,they have not retained any vestige of the power of revolving4 ,it is a curious fact1 that many of these filaments1 when foliaceous1 have on their lower surfaces1 dark-coloured glands like those on the stipules1 which excrete a sweet fluid2 so that these rudiments have been feebly utilized4 ,one other analogous case1 though hypothetical1 is worth giving4 ,nearly all the species of ,lathyrus possesses tendrils2 but ,l4 nissolia is destitute of them4 ,this plant has leaves1 which must have struck everyone with surprise who has noticed them1 for they are quite unlike those of all common papilionaceous plants1 and resemble those of a grass4 ,in another species1 ,l4 aphaca1 the tendril1 which is not highly developed 7for it is unbranched1 and has no spontaneous revolving-power71 replaces the leaves1 the latter being replaced in function by large stipules4 ,now if we suppose the tendrils of ,l4 aphaca to become flattened and foliaceous1 like the little rudimentary tendrils of the bean1 and the large stipules to become at the same time reduced in size1 from not being any longer wanted1 we should have the exact counterpart of ,l4 nissolia1 and its curious leaves are at once rendered intelligible to us4 ,it may be added1 as serving to sum up the foregoing views on the origin of tendril-bearing plants1 that ,l4 nissolia is probably descended from a plant which was primordially a twiner2 this then became a leaf-climber1 the leaves being afterwards converted by degrees into tendrils1 with the stipules greatly increased in size through the law of compensation4 #bjb ,after a time the tendrils lost their branches and became simple2 they then lost their revolving-power 7in which state they would have resembled the tendrils of the existing ,l4 aphaca71 and afterwards losing their prehensile power and becoming foliaceous would no longer be thus designated4 ,in this last stage 7that of the existing ,l4 nissolia7 the former tendrils would reassume their original function of leaves1 and the stipules which were recently much developed being no longer wanted1 would decrease in size4 ,if species become modified in the course of ages1 as almost all naturalists now admit1 we may conclude that ,l4 nissolia has passed through a series of changes1 in some degree like those here indicated4 ,the most interesting point in the natural history of climbing plants is the various kinds of movement which they display in manifest relation to their wants4 ,the most different organs--stems1 branches1 flower-peduncles1 petioles1 mid-ribs of the leaf and leaflets1 and apparently arial roots--all possess this power4 ,the first action of a tendril is to place itself in a proper position4 ,for instance1 the tendril of ,coba first rises vertically up1 with its branches divergent and with the terminal hooks turned outwards2 the young shoot at the extremity of the stem is at the same time bent to one side1 so as to be out of the way4 ,the young leaves of ,clematis1 on the other hand1 prepare for action by temporarily curving themselves downwards1 so as to serve as grapnels4 ,secondly1 if a twining plant or a tendril gets by any accident into an inclined position1 it soon bends upwards1 though secluded from the light4 ,the guiding stimulus no doubt is the attraction of gravity1 as ,andrew ,knight showed to be the case with germinating plants4 ,if a shoot of any ordinary plant be placed in an inclined position in a glass of water in the dark1 the extremity will1 in a few hours1 bend upwards2 and if the position of the shoot be then reversed1 the downward-bent shoot reverses its curvature2 but if the stolen of a strawberry1 which has no tendency to grow upwards1 be thus treated1 it will curve downwards in the direction of1 instead of in opposition to1 the force of gravity4 ,as with the strawberry1 so it is generally with the twining shoots of the ,hibbertia dentata1 which climbs laterally from bush to bush2 for these shoots1 if placed in a position inclined downwards1 show little and sometimes no tendency to curve upwards4 ,thirdly1 climbing plants1 like other plants1 bend towards the light by a movement closely analogous to the incurvation which causes them to revolve1 so that their revolving movement is often accelerated or retarded in travelling to or from the light4 ,on the other hand1 in a few instances tendrils bend towards the dark4 ,fourthly1 we have the spontaneous revolving movement which is independent of any outward stimulus1 but is contingent on the youth of the part1 and on vigorous health2 and this again of course depends on a proper temperature and other favourable conditions of life4 ,fifthly1 tendrils1 whatever their homological nature may be1 and the petioles or tips of the leaves of leaf-climbers1 and apparently certain roots1 all have the power of movement when touched1 and bend quickly towards the touched side4 ,extremely slight pressure often suffices4 ,if the pressure be not permanent1 the part in question straightens itself and is again ready to bend on being touched4 ,sixthly1 and lastly1 tendrils1 soon after clasping a support1 but not after a mere temporary curvature1 contract spirally4 ,if they have not come into contact with any object1 they ultimately contract spirally1 after ceasing to revolve2 but in this case the movement is useless1 and occurs only after a considerable lapse of time4 ,with respect to the means by which these various movements are effected1 there can be little doubt from the researches of ,sachs and ,h4 de ,vries1 that they are due to unequal growth2 but from the reasons already assigned1 ,i cannot believe that this explanation applies to the rapid movements from a delicate touch4 ,finally1 climbing plants are sufficiently numerous to form a conspicuous feature in the vegetable kingdom1 more especially in tropical forests4 ,america1 which so abounds with arboreal animals1 as ,mr4 ,bates remarks1 likewise abounds according to ,mohl and ,palm with climbing plants2 and of the tendril-bearing plants examined by me1 the highest developed kinds are natives of this grand continent1 namely1 the several species of ,bignonia1 ,eccremocarpus1 ,coba1 and ,ampelopsis4 ,but even in the thickets of our temperate regions the number of climbing species and individuals is considerable1 as will be found by counting them4 ,they belong to many and widely different orders4 ,to gain some rude idea of their distribution in the vegetable series1 ,i marked1 from the lists given by ,mohl and ,palm 7adding a few myself1 and a competent botanist1 no doubt1 could have added many more71 all those families in ,lindley's #8,vegetable ,kingdom' which include twiners1 leaf-climbers1 or tendril-bearers4 ,lindley divides ,phanerogamic plants into fifty-nine ,alliances2 of these1 no less than thirty-five include climbing plants of the above kinds1 hook and root-climbers being excluded4 ,to these a few ,cryptogamic plants must be added4 ,when we reflect on the wide separation of these plants in the series1 and when we know that in some of the largest1 well-defined orders1 such as the ,composit1 ,rubiace1 ,scrophulariace1 ,liliace1 c41 species in only two or three genera have the power of climbing1 the conclusion is forced on our minds that the capacity of revolving1 on which most climbers depend1 is inherent1 though undeveloped1 in almost every plant in the vegetable kingdom4 ,it has often been vaguely asserted that plants are distinguished from animals by not having the power of movement4 ,it should rather be said that plants acquire and display this power only when it is of some advantage to them2 this being of comparatively rare occurrence1 as they are affixed to the ground1 and food is brought to them by the air and rain4 ,we see how high in the scale of organization a plant may rise1 when we look at one of the more perfect tendril-bearers4 ,it first places its tendrils ready for action1 as a polypus places its tentacula4 ,if the tendril be displaced1 it is acted on by the force of gravity and rights it self4 ,it is acted on by the light1 and bends towards or from it1 or disregards it1 whichever may be most advantageous4 ,during several days the tendrils or internodes1 or both1 spontaneously revolve with a steady motion4 ,the tendril strikes some object1 and quickly curls round and firmly grasps it4 ,in the course of some hours it contracts into a spire1 dragging up the stem1 and forming an excellent spring4 ,all movements now cease4 ,by growth the tissues soon become wonderfully strong and durable4 ,the tendril has done its work1 and has done it in an admirable manner4 ,,footnotes4 iv ,an ,english translation of the #8,lehrbuch der ,botanik' by ,professor ,sachs1 has recently 7#ahge71 appeared under the title of #8,text-,book of ,botany1' and this is a great boon to all lovers of natural science in ,england4 #a;a #8,proc4 ,amer4 ,acad4 of ,arts and ,sciences1' vol4 iv4 ,aug4 #ab1 #aheh1 p4 #ih4 #a;b ,ludwig ,h4 ,palm1 #8,ueber das ,winden der ,pflanzen2' ,hugo von ,mohl1 #8,ueber den ,bau und des ,winden der ,ranken und ,schlingpflanzen1' #ahbg4 ,palm's ,treatise was published only a few weeks before ,mohl's4 ,see also #8,the ,vegetable ,cell' 7translated by ,henfrey71 by ,h4 von ,mohl1 p4 #adg to end4 #a;c 8,des ,mouvements rvolutife ,respontans10 c41 #8,comptes ,rendus1' tom4 xvii4 7#ahdc7 p4 #ihi2 8,recherches sur la ,volubilit des ,tiges10 c41 tom4 xix4 7#ahdd7 p4 #bie4 #h #8,bull4 ,bot ,soc4 de ,france1' tom4 v4 #aheh1 p4 #cef4 #i;a ,this whole subject has been ably discussed and explained by ,h4 de ,vries1 #8,arbeiten des ,bot4 ,instituts in ,wrzburg1' ,heft iii4 pp4 #cca1 #ccf4 ,see also ,sachs 7#8,text-,book of ,botany1' ,english translation1 #ahge1 p4 #ggj71 who concludes 8that torsion is the result of growth continuing in the outer layers after it has ceased or begun to cease in the inner layers40 #i;b ,professor ,asa ,gray has remarked to me1 in a letter1 that in ,thuja occidentalis the twisting of the bark is very conspicuous4 ,the twist is generally to the right of the observer2 but1 in noticing about a hundred trunks1 four or five were observed to be twisted in an opposite direction4 ,the ,spanish chestnut is often much twisted3 there is an interesting article on this subject in the #8,scottish ,farmer1' #ahfe1 p4 #hcc4 #aj ,it is well known that the stems of many plants occasionally become spirally twisted in a monstrous manner2 and after my paper was read before the ,linnean ,society1 ,dr4 ,maxwell ,masters remarked to me in a letter that 8some of these cases1 if not all1 are dependent upon some obstacle or resistance to their upward growth40 ,this conclusion agrees with what ,i have said about the twisting of stems1 which have twined round rugged supports2 but does not preclude the twisting being of service to the plant by giving greater rigidity to the stem4 #ab ,the view that the revolving movement or nutation of the stems of twining plants is due to growth is that advanced by ,sachs and ,h4 de ,vries2 and the truth of this view is proved by their excellent observations4 #ad ,the mechanism by which the end of the shoot remains hooked appears to be a difficult and complex problem1 discussed by ,dr4 ,h4 de ,vries 7ibid4 p4 #ccg73 he concludes that 8it depends on the relation between the rapidity of torsion and the rapidity of nutation40 #af ,dr4 ,h4 de ,vries also has shown 7ibid4 p4 #cba and #cbe7 by a better method than that employed by me1 that the stems of twining plants are not irritable1 and that the cause of their winding up a support is exactly what ,i have described4 #ag ,dr4 ,h4 de ,vries states 7ibid4 p4 #cbb7 that the stem of ,cuscuta is irritable like a tendril4 #ah ,see ,dr4 ,h4 de ,vries 7ibid4 p4 #cbd7 on this subject4 #ai ,comptes ,rendus1 #ahdd1 tom4 xix4 p4 #bie1 and ,annales des ,sc4 ,nat #crd series1 ,bot41 tom4 ii4 p4 #afc4 #bd ,i am much indebted to ,dr4 ,hooker for having sent me many plants from ,kew2 and to ,mr4 ,veitch1 of the ,royal ,exotic ,nursery1 for having generously given me a collection of fine specimens of climbing plants4 ,professor ,asa ,gray1 ,prof4 ,oliver1 and ,dr4 ,hooker have afforded me1 as on many previous occasions1 much information and many references4 #cc ,journal of the ,linn4 ,soc4 7,bot47 vol4 ix4 p4 #cdd4 ,i shall have occasion often to quote this interesting paper1 in which he corrects or confirms various statements made by me4 #cd ,i raised nine plants of the hybrid ,loasa ,herbertii1 and six of these also reversed their spire in ascending a support4 #cf ,in another genus1 namely ,davilla1 belonging to the same family with ,hibbertia1 ,fritz ,mller says 7ibid4 p4 #cdi7 that 8the stem twines indifferently from left to right1 or from right to left2 and ,i once saw a shoot which ascended a tree about five inches in diameter1 reverse its course in the same manner as so frequently occurs with ,loasa40 #cg ,fritz ,mller states 7ibid4 p4 #cdi7 that he saw on one occasion in the forests of ,south ,brazil a trunk about five feet in circumference spirally ascended by a plant1 apparently belonging to the ,menispermace4 ,he adds in his letter to me that most of the climbing plants which there ascend thick trees1 are root-climbers2 some being tendril-bearers4 #dd ,fritz ,mller has published some interesting facts and views on the structure of the wood of climbing plants in #8,bot4 ,zeitung1' #ahff1 pp4 #eg1 #ff4 #fh ,it appears from ,a4 ,kerner's interesting observations1 that the flower-peduncles of a large number of plants are irritable1 and bend when they are rubbed or shaken3 ,die ,schutzmittel des ,pollens1 #ahgc1 p4 #cd4 #ga ,i have already referred to the case of the twining stem of ,cuscuta1 which1 according to ,h4 de ,vries 7ibid4 p4 #cbb7 is sensitive to a touch like a tendril4 #ge ,dr4 ,maxwell ,masters informs me that in almost all petioles which are cylindrical1 such as those bearing peltate leaves1 the woody vessels form a closed ring2 semilunar bands of vessels being confined to petioles which are channelled along their upper surfaces4 ,in accordance with this statement1 it may be observed that the enlarged and clasped petiole of the ,solanum1 with its closed ring of woody vessels1 has become more cylindrical than it was in its original unclasped condition4 #hd ,never having had the opportunity of examining tendrils produced by the modification of branches1 ,i spoke doubtfully about them in this essay when originally published4 ,but since then ,fritz ,mller has described 7,journal of ,linn4 ,soc4 vol4 ix4 p4 #cdd7 many striking cases in ,south ,brazil4 ,in speaking of plants which climb by the aid of their branches1 more or less modified1 he states that the following stages of development can be traced3 7#a47 ,plants supporting themselves simply by their branches stretched out at right angles--for example1 ,chiococca4 7#b47 ,plants clasping a support with their unmodified branches1 as with ,securidaca4 7#c47 ,plants climbing by the extremities of their branches which appear like tendrils1 as is the case according to ,endlicher with ,helinus4 7#d47 ,plants with their branches much modified and temporarily converted into tendrils1 but which may be again transformed into branches1 as with certain ,papilionaceous plants4 7#e47 ,plants with their branches forming true tendrils1 and used exclusively for climbing--as with ,strychnos and ,caulotretus4 ,even the unmodified branches become much thickened when they wind round a support4 ,i may add that ,mr4 ,thwaites sent me from ,ceylon a specimen of an ,acacia which had climbed up the trunk of a rather large tree1 by the aid of tendril-like1 curved or convoluted branchlets1 arrested in their growth and furnished with sharp recurved hooks4 #he ,as far as ,i can make out1 the history of our knowledge of tendrils is as follows3--,we have seen that ,palm and von ,mohl observed about the same time the singular phenomenon of the spontaneous revolving movement of twining-plants4 ,palm 7p4 #eh71 ,i presume1 observed likewise the revolving movement of tendrils2 but ,i do not feel sure of this1 for he says very little on the subject4 ,dutrochet fully described this movement of the tendril in the common pea4 ,mohl first discovered that tendrils are sensitive to contact2 but from some cause1 probably from observing too old tendrils1 he was not aware how sensitive they were1 and thought that prolonged pressure was necessary to excite their movement4 ,professor ,asa ,gray1 in a paper already quoted1 first noticed the extreme sensitiveness and rapidity of the movements of the tendrils of certain ,cucurbitaceous plants4 #ajb ,fritz ,mller states 7ibid4 p4 #cdh7 that in ,south ,brazil the trifid tendrils of ,haplolophium1 7one of the ,bignoniace7 without having come into contact with any object1 terminate in smooth shining discs4 ,these1 however1 after adhering to any object1 sometimes become considerably enlarged4 #aaa ,comptes ,rendus1 tom4 xvii4 #ahdc1 p4 #ihi4 #aac ,diagram showing the movement of the upper internode of the common ,pea1 traced on a hemispherical glass1 and transferred to paper2 reduced one-half in size 7,aug4 #ast7 ,no4 ,h4 ,m4 #a #h #df ,a4,m4 #b #aj #j #c #aa #j #d #aa #cg #e #ab #g ,p4,m4 #f #ab #cj #g #a #j #h #a #cj #i #a #dd #aj #b #be #aa #c #j #ab #c #cj #ac #c #dh #ad #d #dj #ae #e #e #af #e #be #ag #e #ej #ah #f #be #ai #g #j #bj #g #de #ba #h #cj #bb #i #ae #aah #8,leons de ,botanique1' c41 #ahda1 p4 #agj4 #abg;a ,i am indebted to ,prof4 ,oliver for information on this head4 ,in the ,bulletin de la ,socit ,botanique de ,france1 #aheg1 there are numerous discussions on the nature of the tendrils in this family4 #abg;b #8,gardeners' ,chronicle1' #ahfd1 p4 #gba4 ,from the affinity of the ,cucurbitace to the ,passiflorace1 it might be argued that the tendrils of the former are modified flower-peduncles1 as is certainly the case with those of ,passion flowers4 ,mr4 ,r4 ,holland 7,hardwicke's #8,science-,gossip1' #ahfe1 p4 #aje7 states that 8a cucumber grew1 a few years ago in my own garden1 where one of the short prickles upon the fruit had grown out into a long1 curled tendril40 #ade ,trans4 ,phil4 ,soc4 #ahab1 p4 #cad4 #adf ,dr4 ,m',nab remarks 7,trans4 ,bot4 ,soc4 ,edinburgh1 vol xi4 p4 #bib7 that the tendrils of ,amp4 ,veitchii bear small globular discs before they have came into contact with any object2 and ,i have since observed the same fact4 ,these discs1 however1 increase greatly in size1 if they press against and adhere to any surface4 ,the tendrils1 therefore1 of one species of ,ampelopsis require the stimulus of contact for the first development of their discs1 whilst those of another species do not need any such stimulus4 ,we have seen an exactly parallel case with two species of ,bignoniace4 #aeb ,fritz ,mller remarks 7ibid4 p4 #cdh7 that a related genus1 ,serjania1 differs from ,cardiospermum in bearing only a single tendril2 and that the common peduncle contracts spirally1 when1 as frequently happens1 the tendril has clasped the plant's own stem4 #aed ,prof4 ,asa ,gray informs me that the tendrils of ,p4 sicyoides revolve even at a quicker rate than those of ,p4 gracilis2 four revolutions were completed 7the temperature varying from #hh degrees-#ib degrees ,fahr47 in the following times1 #dj m41 #de m41 #ch m41 and #df m4 ,one half-revolution was performed in #ae m4 #afe ,see ,m4 ,isid4 ,lon in ,bull4 ,soc4 ,bot4 de ,france1 tom4 v4 #aheh1 p4 #fej4 ,dr4 ,h4 de ,vries points out 7p4 #cjf7 that ,i have overlooked1 in the first edition of this essay1 the following sentence by ,mohl3 8,after a tendril has caught a support1 it begins in some days to wind into a spire1 which1 since the tendril is made fast at both extremities1 must of necessity be in some places to the right1 in others to the left40 ,but ,i am not surprised that this brief sentence1 without any further explanation did not attract my attention4 #agf ,sachs1 however 7#8,text-,book of ,botany1' ,eng4 ,translation1 #ahge1 p4 #bhj71 has shown that which ,i overlooked1 namely1 that the tendrils of different species are adapted to clasp supports of different thicknesses4 ,he further shows that after a tendril has clasped a support it subsequently tightens its hold4 #agi ,annales des ,sc4 ,nat4 ,bot4 #dth series1 tom4 xii4 p4 #hi4 #ahj ,it occurred to me that the movement of notation and that from a touch might be differently affected by ansthetics1 in the same manner as ,paul ,bert has shown to be the case with the sleep-movements of ,mimosa and those from a touch4 ,i tried the common pea and ,passiflora gracilis1 but ,i succeeded only in observing that both movements were unaffected by exposure for #a hrs4 to a rather large dose of sulphuric ether4 ,in this respect they present a wonderful contrast with ,drosera1 owing no doubt to the presence of absorbent glands in the latter plant4 #aha ,text-,book of ,botany1 #ahge1 p4 #ggi4 #ahc ,journal of ,linn4 ,soc4 vol4 ix4 p4 #cdh4 ,professor ,g4 ,jaeger has well remarked 7#8,in ,sachen ,darwin's1 insbesondere contra ,wigand1' #ahgd1 p4 #ajf7 that it is highly characteristic of climbing plants to produce thin1 elongated1 and flexible stems4 ,he further remarks that plants growing beneath other and taller species or trees1 are naturally those which would be developed into climbers2 anti such plants1 from stretching towards the light1 and from not being much agitated by the wind1 tend to produce long1 thin and flexible shoots4 #ahd ,professor ,asa ,gray has explained1 as it would appear1 this difficulty in his review 7,american ,journal of ,science1 vol4 xl4 ,sept4 #ahfe1 p4 #bhb7 of the present work4 ,he has observed that the strong summer shoots of the ,michigan rose 7,rosa setigera7 are strongly disposed to push into dark crevices and away from the light1 so that they would be almost sure to place themselves under a trellis4 ,he adds that the lateral shoots1 made on the following spring emerged from the trellis as they sought the light4 #ahg ,mr4 ,spiller has recently shown 7,chemical ,society1 ,feb4 #af1 #ahfe71 in a paper on the oxidation of india-rubber or caoutchouc1 that this substance1 when exposed in a fine state of division to the air1 gradually becomes converted into brittle1 resinous matter1 very similar to shell-lac4 #ahh ,fritz ,mller informs me that he saw in the forests of ,south ,brazil numerous black strings1 from some lines to nearly an inch in diameter1 winding spirally round the trunks of gigantic trees4 ,at first sight he thought that they were the stems of twining plants which were thus ascending the trees3 but he afterwards found that they were the arial roots of a ,philodendron which grew on the branches above4 ,these roots therefore seem to be true twiners1 though they use their powers to descend1 instead of to ascend like twining plants4 ,the arial roots of some other species of ,philodendron hang vertically downwards1 sometimes for a length of more than fifty feet4 #aig ,quoted by ,cohn1 in his remarkable memoir1 8,contractile ,gewebe im ,pflanzenreiche10 #8,abhandl4 der ,schlesischen ,gesell4 #ahfa1 ,heft i4 s4 #ce4 #aih ,such slight spontaneous movements1 ,i now find1 have been for some time known to occur1 for instance with the flower-stems of ,brassica napus and with the leaves of many plants3 ,sachs' #8,text-,book of ,botany' #ahge1 pp4 #gff1 #ghe4 ,fritz ,mller also has shown in relation to our present subject 7#8,jenaischen ,zeitschrift1' ,bd4 ,v4 ,heft #b1 p4 #acc7 that the stems1 whilst young1 of an ,alisma and of a ,linum are continually performing slight movements to all points of the compass1 like those of climbing plants4 #aii ,mr4 ,herbert ,spencer has recently argued 7#8,principles of ,biology1' #ahfe1 p4 #cg et seq47 with much force that there is no fundamental distinction between the foliar and axial organs of plants4 #bjj ,annales des ,sc4 ,nat4 #dth series1 ,bot4 tom4 vi4 #ahef1 p4 #ca4 #bjb ,moquin-,tandon 7,elments de ,tratologie4 #ahda1 p4 #aef7 gives the case of a monstrous bean1 in which a case of compensation of this nature was suddenly effected2 for the leaves completely disappeared and the stipules grew to an enormous size4