Transcription complète de Chapter 4

and when they were tied up, but was perhaps most 65 00:04:23.000 --> 00:04:25.959 conspicuous in the latter case, or when the whole shoot 66 00:04:26.040 --> 00:04:29.560 happened to be much inclined. The tendril forms a very 67 00:04:29.600 --> 00:04:33.439 acute angle with the projecting extremity of the stem or shoot, 68 00:04:33.720 --> 00:04:37.079 and the stiffening always occurred as the tendril approached and 69 00:04:37.120 --> 00:04:39.639 had to pass over the chute in its circular course. 70 00:04:40.319 --> 00:04:43.480 If it had not possessed and exercised this curious power, 71 00:04:43.759 --> 00:04:47.199 it would infallibly have struck against the extremity of the 72 00:04:47.279 --> 00:04:50.319 chute and been arrested. As soon as the tendril, with 73 00:04:50.360 --> 00:04:53.639 its three branches, begins to stiffen itself in this manner 74 00:04:54.199 --> 00:04:56.839 and to rise from an inclined to a vertical position, 75 00:04:57.240 --> 00:05:00.600 the revolving motion becomes more rapid, and as soon as 76 00:05:00.600 --> 00:05:03.519 the tendril has succeeded in passing over the extremity of 77 00:05:03.560 --> 00:05:07.199 the shoot or point of difficulty in its motion, coinciding 78 00:05:07.240 --> 00:05:10.600 with that from its weight, often causes it to fall 79 00:05:10.680 --> 00:05:14.399 into its previously inclined position so quickly that the apex 80 00:05:14.439 --> 00:05:16.839 could be seen traveling like the minute hand of a 81 00:05:16.879 --> 00:05:21.000 gigantic clock. The tendrils are thin, from seven to nine 82 00:05:21.040 --> 00:05:24.160 inches in length, with a pair of short lateral branches 83 00:05:24.399 --> 00:05:27.959 rising not far from the base. The tip is slightly 84 00:05:28.000 --> 00:05:30.639 and permanently curved, so as to act to a limited 85 00:05:30.680 --> 00:05:34.040 extent as a hook. The concave side of the tip 86 00:05:34.120 --> 00:05:38.040 is highly sensitive to touch, but not so the convex side, 87 00:05:38.279 --> 00:05:40.680 as was likewise observed to be the case with other 88 00:05:40.759 --> 00:05:44.399 species of the family. By Mole, page sixty five. I 89 00:05:44.480 --> 00:05:48.600 repeatedly proved this difference by lightly rubbing four or five 90 00:05:48.680 --> 00:05:52.000 times the convex side of one tendril, and only once 91 00:05:52.120 --> 00:05:55.519 or twice the concave side of another tendril, and the 92 00:05:55.600 --> 00:05:59.519 later alone curled inwards. In a few hours afterwards, when 93 00:05:59.560 --> 00:06:01.959 the tendril which had been rubbed on the concave side 94 00:06:02.000 --> 00:06:05.120 had straightened themselves, I reversed the process of rubbing, and 95 00:06:05.319 --> 00:06:09.160 always with the same result. After touching the concave side, 96 00:06:09.160 --> 00:06:12.319 the tip becomes sensibly curved in one or two minutes, 97 00:06:12.639 --> 00:06:15.439 and subsequently, if the touch has been at all rough, 98

00:06:15.720 --> 00:06:19.319 it coils itself into a helix. But the helix will 99 00:06:19.439 --> 00:06:23.240 after a time straighten itself and be again ready to act. 100 00:06:23.920 --> 00:06:26.519 A loop of thin thread only one sixteenth of a 101 00:06:26.600 --> 00:06:30.759 grain in weight caused a temporary flexure. The lower part 102 00:06:30.879 --> 00:06:35.639 was repeatedly rubbed rather roughly, but no curvature ensued. Yet 103 00:06:35.680 --> 00:06:38.959 this part is sensitive to prolonged pressure, for when it 104 00:06:39.000 --> 00:06:42.000 came into contact with a stick, it would slowly wind 105 00:06:42.079 --> 00:06:45.480 round it. One of my plants bore two shoots near together, 106 00:06:45.560 --> 00:06:48.959 and the tendles were repeatedly drawn across one another. But 107 00:06:49.079 --> 00:06:51.879 it is a singular fact that they did not once 108 00:06:52.000 --> 00:06:54.519 catch each other, it would appear as if they had 109 00:06:54.560 --> 00:06:58.480 become habituated to contact of this kind, for the pressure 110 00:06:58.560 --> 00:07:02.000 thus caused must have been much greater than that caused 111 00:07:02.000 --> 00:07:05.000 by a loop of soft thread weighing only the one 112 00:07:05.120 --> 00:07:09.360 sixteenth of a grain. I have, however, seen several tendrils 113 00:07:09.600 --> 00:07:15.120 of Bryonia diochia interlocked, but they subsequently released one another. 114 00:07:16.160 --> 00:07:20.480 The tendrils of the echinocystis are also habituated to drops 115 00:07:20.480 --> 00:07:24.319 of water or terrain. For artificial rain made by violently 116 00:07:24.360 --> 00:07:28.680 flirting a wet brush over them produced not the least effect. 117 00:07:29.759 --> 00:07:32.920 The revolving movement of a tendril is not stopped by 118 00:07:32.959 --> 00:07:35.839 the curving of its extremity after it has been touched. 119 00:07:36.399 --> 00:07:39.519 When one of the lateral branches has firmly clasped an object, 120 00:07:39.839 --> 00:07:43.399 the middle branch continues to revolve. When a stem is 121 00:07:43.439 --> 00:07:46.279 bent down and secured, so that the tendril depends but 122 00:07:46.560 --> 00:07:50.160 is left free to move. Its previous revolving movement is 123 00:07:50.279 --> 00:07:53.360 nearly or quite stopped, but it soon begins to bend 124 00:07:53.480 --> 00:07:57.480 upwards as soon as it has become horizontal. The revolving 125 00:07:57.600 --> 00:08:02.560 movement recommendss I tried the four times. The tendril generally 126 00:08:02.639 --> 00:08:05.120 rose to a horizontal position in an hour or an 127 00:08:05.160 --> 00:08:07.600 hour and a half, but in one case in which 128 00:08:07.639 --> 00:08:11.199 a tenrol depended at an angle of forty five degrees 129 00:08:11.240 --> 00:08:15.600 beneath the horizon, the uprising took two hours. In half 130 00:08:15.639 --> 00:08:18.759 an hour afterwards, it rose to twenty three degrees above 131 00:08:18.800 -->

00:08:22.839 the horizon and then recommenced revolving. This upward movement is 132 00:08:22.920 --> 00:08:26.560 independent of the action of light. Broad occurred twice in 133 00:08:26.600 --> 00:08:29.639 the dark, and on another occasion the light came in 134 00:08:29.800 --> 00:08:33.639 on one side alone. The movement, no doubt is guided 135 00:08:33.639 --> 00:08:36.320 by opposition to the force of gravity, as in the 136 00:08:36.360 --> 00:08:39.720 case of the ascent of the pumerles of germinating Sea. 137 00:08:40.080 --> 00:08:43.279 A tendril does not long retain its revolving power, and 138 00:08:43.360 --> 00:08:45.960 as soon as this is lost, it bends downwards and 139 00:08:46.039 --> 00:08:50.639 contracts spirally. After the revolving movement has ceased, the tip 140 00:08:50.720 --> 00:08:54.120 still retains for a short time its sensitiveness to contact, 141 00:08:54.559 --> 00:08:56.679 but this can be of little or no use to 142 00:08:56.720 --> 00:09:00.159 the planet. Though the tendril is highly flexible, and though 143 00:09:00.200 --> 00:09:04.399 the extremity travels under favorable circumstances at about the rate 144 00:09:04.480 --> 00:09:07.039 of an inch and two minutes, and a quarter. Yet 145 00:09:07.120 --> 00:09:10.600 its sensitiveness to contact is so great that it hardly 146 00:09:10.679 --> 00:09:13.840 ever fails to seize a thin stick placed in its path. 147 00:09:14.559 --> 00:09:17.759 The following case surprised me much. I placed a thin, 148 00:09:17.840 --> 00:09:22.080 smooth cylindrical stick, and I repeated the experiment seven times, 149 00:09:22.399 --> 00:09:25.080 so far from a tendril that its extremity could only 150 00:09:25.120 --> 00:09:28.320 curl half or three quarters round the stick. But I 151 00:09:28.360 --> 00:09:30.559 always found that the tip managed, in the course of 152 00:09:30.600 --> 00:09:33.600 a few hours to curl twice or even thrice round 153 00:09:33.679 --> 00:09:36.960 the stick. I at first thought that this was due 154 00:09:37.000 --> 00:09:40.600 to rapid growth on the outside, but the color points 155 00:09:40.600 --> 00:09:44.399 and measurements I proved that there had been no sensible 156 00:09:44.480 --> 00:09:48.120 increase of length within the time. When a stick flat 157 00:09:48.159 --> 00:09:51.240 on one side was similarly placed, the tip of the 158 00:09:51.279 --> 00:09:55.080 tendril could not curl beyond the flat surface, but coiled 159 00:09:55.120 --> 00:09:58.799 itself into a helix, which, turning to one side, lay 160 00:09:58.879 --> 00:10:02.519 flat on the little flat surface of the wood. In 161 00:10:02.600 --> 00:10:05.720 one instance, a portion of tendril three quarters of an 162 00:10:05.720 --> 00:10:09.240 achine length was thus dragged on to the flat surface 163 00:10:09.559 --> 00:10:12.840 by the coiling in of the helix. But the tendril 164 00:10:12.919 --> 00:10:17.000 thus acquires a very insecure hold, and generally after a 165

00:10:17.120 --> 00:10:21.600 time slips off in one case alone. The helix subsequently 166 00:10:21.720 --> 00:10:25.879 uncoiled itself and the tip that then passed round and 167 00:10:26.039 --> 00:10:29.679 clasped the stick. The formation of the helix on the 168 00:10:29.679 --> 00:10:32.320 flat side of the stick apparently shows us that the 169 00:10:32.360 --> 00:10:36.240 continued striving of the tip to curl itself closely inwards 170 00:10:36.600 --> 00:10:39.919 gives the force which drags the tendril round a smooth 171 00:10:39.919 --> 00:10:44.240 cylindrical stick. In this latter case, whilst the tendril was 172 00:10:44.279 --> 00:10:49.399 slowly and quite insensibly crawling onwards, I observed several times 173 00:10:49.399 --> 00:10:51.799 through a lens that the whole surface was not in 174 00:10:51.840 --> 00:10:55.279 close contact with the stick, and I can understand the 175 00:10:55.360 --> 00:10:58.919 onward progress only by supposing that the movement is slightly 176 00:10:59.000 --> 00:11:03.799 undulatory or vermicular, and that the tip alternately straightens itself 177 00:11:03.840 --> 00:11:07.639 a little and then again curls inwards. It thus drags 178 00:11:07.679 --> 00:11:12.120 itself onwards by an insensibly slow, alternate movement, which may 179 00:11:12.159 --> 00:11:14.679 be compared to that of a strong man suspended by 180 00:11:14.679 --> 00:11:17.720 the ends of his fingers to a horizontal pole, who 181 00:11:17.759 --> 00:11:20.679 works his fingers onwards until he can grasp the hole 182 00:11:20.720 --> 00:11:23.960 with the palm of his hand. However this may be, 183 00:11:24.480 --> 00:11:26.720 the fact is certain that a tendril which is caught 184 00:11:26.759 --> 00:11:30.000 a round stick with its extreme point can work itself 185 00:11:30.080 --> 00:11:33.120 onwards until it has passed twice or even thrice round 186 00:11:33.159 --> 00:11:38.960 the stick and has permanently grasped it. Hamburia mexicana. The 187 00:11:39.000 --> 00:11:42.039 young internotes and tendrils of this anomalous member of the 188 00:11:42.080 --> 00:11:44.759 family revolve in the same manner and at about the 189 00:11:44.799 --> 00:11:48.519 same rate as those of the ichinocystus. The stem does 190 00:11:48.559 --> 00:11:51.399 not twine, but can incend an upright stick by the 191 00:11:51.440 --> 00:11:54.840 aid of its tendrils. The concave tip of the tendril 192 00:11:54.960 --> 00:11:58.919 is very sensitive. After it had become rapidly coiled into 193 00:11:58.960 --> 00:12:02.120 a ring, owing to a light touch, it straightens itself 194 00:12:02.159 --> 00:12:06.279 in fifty minutes. The tendril, when in full action, stands 195 00:12:06.360 --> 00:12:09.799 vertically up with the projecting extremity of the young stem, 196 00:12:10.080 --> 00:12:12.519 thrown a little on one side so as to be 197 00:12:12.600 --> 00:12:15.480 out of the way, but the tendril bears on the 198 00:12:15.519 --> 00:12:19.639 inner side near its base a short rigid branch which 199 00:12:19.679 --> 00:12:22.720 projects out at right ankles like a spur, with the 200 00:12:22.879 --> 00:12:26.919 terminal half bowed a little downwards. Hence, as the main 201 00:12:27.039 --> 00:12:30.759 vertical branch revolves, the spur from its position and rigidity 202 00:12:31.120 --> 00:12:33.759 cannot pass over the extremity of the shoot in the 203 00:12:33.799 --> 00:12:36.759 same curious manner as do the three branches of the 204 00:12:36.799 --> 00:12:40.600 tendril of the itchin of Cistus, namely by stiffening themselves 205 00:12:40.639 --> 00:12:44.559 at the proper point. The spur is therefore pressed laterally 206 00:12:44.600 --> 00:12:47.840 against the young stem in one part of the revolving course, 207 00:12:48.240 --> 00:12:50.320 and thus the sweep of the lower part of the 208 00:12:50.360 --> 00:12:54.759 main branch is much restricted. A nice case of coadaptation 209 00:12:54.919 --> 00:12:58.679 here comes into play. All the other tendrils observed by 210 00:12:58.759 --> 00:13:02.279 me the several brands become sensitive at the same period. 211 00:13:02.840 --> 00:13:06.000 Had this been the case with the hanbaria, the inwardly 212 00:13:06.039 --> 00:13:10.080 directed spur like branch, from being pressed during the revolving 213 00:13:10.320 --> 00:13:14.279 movement against the projecting end of the chute, would infallibly 214 00:13:14.600 --> 00:13:18.240 have seized it in a useless or injurious manner. But 215 00:13:18.320 --> 00:13:20.720 the main branch of the tendril, after evolving for a 216 00:13:20.759 --> 00:13:25.000 time in a vertical position, horizontally bends downwards, and in 217 00:13:25.120 --> 00:13:28.919 doing so raises the spur like branch, which itself also 218 00:13:29.039 --> 00:13:33.080 curves upwards, so that by these combined movements it rises 219 00:13:33.159 --> 00:13:35.799 above the projecting end of the chute and can now 220 00:13:35.879 --> 00:13:39.159 move freely without touching the chute and now. It first 221 00:13:39.200 --> 00:13:43.360 becomes sensitive. The tips of both branches when they come 222 00:13:43.399 --> 00:13:47.159 into contact with a stick grasp it like any ordinary tendril. 223 00:13:47.639 --> 00:13:49.879 But in the course of a few days, the lower 224 00:13:49.919 --> 00:13:53.600 surface swells and becomes developed into a cellular layer which 225 00:13:53.879 --> 00:13:57.440 adapts itself closely to the wood and firmly adheres to it. 226 00:13:58.080 --> 00:14:01.000 This layer is analogous to the adhesive of discs formed 227 00:14:01.000 --> 00:14:03.759 by the extremities of the tendrils of some species of 228 00:14:03.799 --> 00:14:08.000 Bignonia and of Empelopsis, but in Hamburia the layer is 229 00:14:08.039 --> 00:14:12.039 developed along the terminal inner surface, sometimes for a length 230 00:14:12.120 --> 00:14:15.519 of one three fourths inches, and not at the extreme tip. 231

00:14:16.240 --> 00:14:19.080 The layer is white whilst the tendril is green, and 232 00:14:19.159 --> 00:14:22.639 near the tip it is sometimes thicker than the tendril itself. 233 00:14:23.200 --> 00:14:26.000 It generally spreads a little beyond the sides of the 234 00:14:26.039 --> 00:14:30.240 tendril and is fringed with free elongated cells, which have 235 00:14:30.399 --> 00:14:35.440 in large, globular or rivetort shaped heads. This cellular layer 236 00:14:35.559 --> 00:14:39.440 apparently secretes some resinous cement, for its adhesion to the 237 00:14:39.480 --> 00:14:42.120 wood was not lessened by an immersion of twenty four 238 00:14:42.159 --> 00:14:46.080 hours in alcohol or water, but was quite loosened by 239 00:14:46.120 --> 00:14:50.480 a similar immersion in ether. Or turpentine. After a tendril 240 00:14:50.559 --> 00:14:53.840 has once firmly coiled itself round a stick, it is 241 00:14:53.879 --> 00:14:57.600 difficult to imagine of what use the adhesive cellular layer 242 00:14:57.639 --> 00:15:01.840 can be. Owing to the spiral contraction which soon ensues. 243 00:15:02.120 --> 00:15:05.799 The tendrils were never able to remain, excepting in one instance, 244 00:15:05.919 --> 00:15:09.279 in contact with a thick post or a nearly flat surface. 245 00:15:09.919 --> 00:15:12.559 If they had quickly become attached by means of the 246 00:15:12.559 --> 00:15:15.919 adhesive layer, this would evidently have been of service to 247 00:15:15.960 --> 00:15:22.600 the plant. The tendrils of Bryonia dioca, Cucurbita, ovifera, and 248 00:15:23.879 --> 00:15:29.120 Satava are sensitive and revolve whether the internodes likewise revolve 249 00:15:29.159 --> 00:15:34.360 I did not observe in Anguria or Skwiski. The internodes, 250 00:15:34.440 --> 00:15:38.000 though thick and stiff, revolve in this plant. The lower 251 00:15:38.039 --> 00:15:41.000 surface of the tendril, some time after classm a stick 252 00:15:41.320 --> 00:15:45.159 produces a coarsely cellular layer or cushion, which adapts itself 253 00:15:45.200 --> 00:15:48.159 closely to the wood, like that formed by the tendril 254 00:15:48.200 --> 00:15:51.440 of the Hambura, but it is not in the least adhesive. 255 00:15:52.159 --> 00:15:55.600 In Zannonia Indica, which belongs to a different tribe of 256 00:15:55.600 --> 00:15:59.080 the family, the forked tendrils and the internodes revolve in 257 00:15:59.159 --> 00:16:02.440 periods between two hours eight minutes and three hours thirty 258 00:16:02.440 --> 00:16:08.240 five minutes, moving against the sun. The tasia in this family, 259 00:16:08.320 --> 00:16:12.799 and in the two following, namely the Sapandacia and the Passifloracia, 260 00:16:13.320 --> 00:16:17.000 the tendrils are modified flower peduncles, and are therefore axial 261 00:16:17.080 --> 00:16:20.320 in their nature. In this respect they differ from all 262 00:16:20.399 --> 00:16:24.360 those previously described, with the exception perhaps of the

cucurbitasia. 263 00:16:25.159 --> 00:16:28.159 The homological nature, however, of a tendril seems to make 264 00:16:28.240 --> 00:16:33.519 no difference in its actions. Vitis vinifera. The tendril is 265 00:16:33.600 --> 00:16:36.480 thick and of great length. One from a vine growing 266 00:16:36.519 --> 00:16:39.799 out of doors and not vigorously was sixteen inches long. 267 00:16:40.360 --> 00:16:43.919 It consists of a peduncle a bearing two branches which 268 00:16:44.039 --> 00:16:47.600 diverge equally from it. One of the branches b has 269 00:16:47.639 --> 00:16:50.639 a scale at its base. It is always as far 270 00:16:50.679 --> 00:16:54.200 as I have seen, longer than the other, and often bifurcates. 271 00:16:54.600 --> 00:16:58.480 The branches, when rubbed, become curved and subsequently straighten themselves. 272 00:16:59.039 --> 00:17:02.200 After a tendril has clasped any object with its extremity, 273 00:17:02.279 --> 00:17:06.799 it contracts spirally, but this does not occur Palm, page 274 00:17:06.839 --> 00:17:10.960 fifty six. When no object has been seized. The tendrils 275 00:17:11.000 --> 00:17:14.480 move spontaneously from side to side, and on a very 276 00:17:14.480 --> 00:17:17.720 hot day one made two elliptical revolutions at an average 277 00:17:17.799 --> 00:17:21.319 rate of two hours fifteen minutes. During these movements, a 278 00:17:21.400 --> 00:17:25.119 colored line painted along the convex surface appeared after a 279 00:17:25.160 --> 00:17:28.640 time on one side, then on the concave side, then 280 00:17:28.720 --> 00:17:32.400 on the opposite side, and lastly again on the convex side. 281 00:17:32.880 --> 00:17:36.519 The two branches of the same tendril have independent movements. 282 00:17:37.079 --> 00:17:40.559 After a tendril has spontaneously revolved for time, it bends 283 00:17:40.680 --> 00:17:43.720 from the light towards the dark. I do not state 284 00:17:43.799 --> 00:17:46.839 this on myne own authority, but on that of Mole 285 00:17:46.920 --> 00:17:50.960 and Dutrochet. Mole, page seventy seven says that in a 286 00:17:51.039 --> 00:17:54.279 vine planted against a wall, the tendrils pointed towards it, 287 00:17:54.599 --> 00:17:57.440 and in a vineyard generally more or less to the north, 288 00:17:57.880 --> 00:18:03.079 the young internodes revolve spontaneaneously, but the movement is unusually slight. 289 00:18:03.759 --> 00:18:06.359 A shute faced a window, and I traced its course 290 00:18:06.400 --> 00:18:09.279 on the glass during two perfectly calm and hot days. 291 00:18:09.880 --> 00:18:12.440 On one of these days, it described in the course 292 00:18:12.519 --> 00:18:16.319 of ten hours aspire, representing two and a half ellipses. 293 00:18:16.880 --> 00:18:19.640 I also placed a bell glass over a young wiscot 294 00:18:19.720 --> 00:18:22.480 grape in the hot house, and it made each day 295 00:18:22.640 --> 00:18:26.799 three or four very small oval revolutions, the shoot moving 296 00:18:26.880 --> 00:18:29.960 less than half an inch from side to side. Had 297 00:18:30.000 --> 00:18:33.079 it not made at least three revolutions whilst the sky 298 00:18:33.319 --> 00:18:36.920 was uniformly overcast, I should have attributed this slight degree 299 00:18:36.960 --> 00:18:39.880 of movement to the varying action of the light. But 300 00:18:40.000 --> 00:18:43.279 the extremity of the stem is more or less bent downwards, 301 00:18:43.559 --> 00:18:47.039 but it never reverses its curvature, as so generally occurs 302 00:18:47.079 --> 00:18:53.039 with training plants. Various authors Palm, page fifty five, More, 303 00:18:53.160 --> 00:18:57.240 page forty five, Linley et cetera believe that the tendrils 304 00:18:57.240 --> 00:19:00.599 of the vine are modified flower peduncles. Here give a 305 00:19:00.680 --> 00:19:03.640 drawing Fig. Ten of the ordinary state of a young 306 00:19:03.680 --> 00:19:07.920 flower stock. It consists of the common peduncle A, of 307 00:19:07.960 --> 00:19:11.640 the flower tendril B, which is represented as having caught 308 00:19:11.759 --> 00:19:14.880 a twig, and of the sub peduncle C bearing the 309 00:19:14.880 --> 00:19:19.319 flower buds. The whole moves spontaneously like a true tendril, 310 00:19:19.680 --> 00:19:23.279 but in a less degree. The movement, however, is greater 311 00:19:23.720 --> 00:19:27.400 when the subpeduncle C does not bear any flower buds. 312 00:19:27.960 --> 00:19:31.039 The common peduncle A has not the power of clasping 313 00:19:31.039 --> 00:19:35.200 a support, nor has the corresponding part of a true tendril. 314 00:19:35.960 --> 00:19:38.799 The flower tendril B is always longer than the sub 315 00:19:38.839 --> 00:19:42.720 peduncle C, and has a scale at its base. It 316 00:19:42.839 --> 00:19:46.720 sometimes bifurcates, and therefore corresponds in every detail with the 317 00:19:46.799 --> 00:19:51.359 longer scale bearing branch B Figure nine of the true tendril. 318 00:19:52.039 --> 00:19:55.720 It is, however, inclined backwards from the subpeduncle C, or 319 00:19:55.799 --> 00:19:59.039 stands at right angles with it, and is thus adapted 320 00:19:59.319 --> 00:20:03.599 to aid in carrying the future bunch of grapes. When rubbed, 321 00:20:03.640 --> 00:20:07.680 it curves and subsequently straightens itself, and it can, as 322 00:20:07.680 --> 00:20:11.279 shown in the drawing, securely clasp a support. I have 323 00:20:11.359 --> 00:20:14.960 seen an object as soft as a young vine leaf 324 00:20:15.079 --> 00:20:18.400 caught by one The lower and naked part of the 325 00:20:18.440 --> 00:20:22.480 sub peduncle SEA is likewise slightly sensitive to a rub, 326 00:20:22.519 --> 00:20:24.720 and I have seen it bend round a stick, and 327 00:20:24.839 --> 00:20:27.599 even partly round a leaf with which it had come 328 00:20:27.680 --> 00:20:31.519 into contact. That the sub peduncle has the same nature 329 00:20:31.559 -->

00:20:34.799 as the corresponding branch of an ordinary tendril is well 330 00:20:34.880 --> 00:20:38.319 shown when it bears only a few flowers, For in 331 00:20:38.359 --> 00:20:42.200 this case it becomes less branched, increases in length, and 332 00:20:42.279 --> 00:20:46.519 gains both insensitiveness and in the power of spontaneous movement. 333 00:20:47.359 --> 00:20:50.759 I have twice seen sub peduncles which bore from thirty 334 00:20:50.759 --> 00:20:54.799 to forty flower buds, and which had become considerably elongated 335 00:20:55.119 --> 00:20:59.480 and were completely wound round sticks, exactly like true tendrils. 336 00:21:00.480 --> 00:21:04.359 The whole length of another sub peduncle bearing only eleven 337 00:21:04.440 --> 00:21:09.039 flower buds quickly became curved when slightly rubbed. But even 338 00:21:09.200 --> 00:21:13.119 this scanty number of flowers rendered the stock less sensitive 339 00:21:13.200 --> 00:21:16.480 than the other branch, that is, the fat flower tendril. 340 00:21:17.119 --> 00:21:20.079 For the latter, after a slight rub became curved more 341 00:21:20.160 --> 00:21:23.400 quickly and in a greater degree. I have seen a 342 00:21:23.400 --> 00:21:26.880 sub peduncle thickly covered with flower buds, with one of 343 00:21:26.880 --> 00:21:31.480 its higher lateral branchlets bearing from some cause only two bugs, 344 00:21:31.839 --> 00:21:35.240 and this one branchlet had become much elongated and had 345 00:21:35.279 --> 00:21:39.319 spontaneously caught hold of an adjoining twig. In fact, it 346 00:21:39.440 --> 00:21:43.920 formed a little subtendril. The increasing length of the subtendril 347 00:21:44.039 --> 00:21:46.839 sea with the decreasing number of the flower buds, is 348 00:21:46.880 --> 00:21:50.920 a good instance of the law of compensation. In accordance 349 00:21:51.000 --> 00:21:54.119 with this same principle, the true tendril as a whole 350 00:21:54.240 --> 00:21:57.799 is always longer than the flower stalk. For instance, on 351 00:21:57.960 --> 00:22:01.799 the same plant, the longest flower measured from the base 352 00:22:01.880 --> 00:22:04.599 of the common peduncle to the tip of the flower tendril, 353 00:22:05.079 --> 00:22:08.799 was eight one half inches in length, whilst the longest 354 00:22:08.799 --> 00:22:13.480 tendril was nearly double this length, namely sixteen inches. The 355 00:22:13.519 --> 00:22:16.640 gradations from the ordinary state of a flower stalk, as 356 00:22:16.720 --> 00:22:19.839 represented in the drawing figure ten, to that of a 357 00:22:19.920 --> 00:22:23.839 true tendril the year nine are complete. We have seen 358 00:22:23.880 --> 00:22:27.240 that the suba peduncle c, whilst still bearing from thirty 359 00:22:27.240 --> 00:22:31.079 to forty flower buds, sometimes becomes a little elongated and 360 00:22:31.200 --> 00:22:34.599 partially assumes all the characters of the corresponding branch of 361 00:22:34.640 --> 00:22:38.079 a

true tendril. From this state we can trace every 362 00:22:38.160 --> 00:22:41.440 stage till we come to a full sized perfect tendril 363 00:22:41.759 --> 00:22:45.079 bearing on the branch which corresponds with the subpeduncle one 364 00:22:45.240 --> 00:22:48.440 single flower bud. Hence there can be no doubt that 365 00:22:48.519 --> 00:22:52.920 the tendril is a modified flower peduncle. Another kind of 366 00:22:52.960 --> 00:22:58.079 gradation well deserves notice. Flower tendrils b. Fig. Ten sometimes 367 00:22:58.160 --> 00:23:02.039 produce a few flower buds. For instance, on a vine 368 00:23:02.079 --> 00:23:05.880 growing against my house, there were thirteen and twenty two 369 00:23:06.000 --> 00:23:10.319 flower buds, respectively on two flower tendrils, which still retained 370 00:23:10.359 --> 00:23:15.000 their characteristic qualities of sensitiveness and spontaneous movement, but in 371 00:23:15.039 --> 00:23:18.920 a somewhat lessened degree on vines. In hot houses, so 372 00:23:18.960 --> 00:23:22.119 many flowers are occasionally produced on the flower tendrils that 373 00:23:22.240 --> 00:23:24.960 a double bunch of grapes is the result, and this 374 00:23:25.119 --> 00:23:29.279 is technically called by gardeners a cluster. In this state, 375 00:23:29.640 --> 00:23:33.319 the whole bunch of flowers, which presents scarcely any resemblance 376 00:23:33.359 --> 00:23:36.400 to a tendril, and judging from the facts already given, 377 00:23:36.720 --> 00:23:39.839 it would probably possess little power of clasping the support 378 00:23:40.400 --> 00:23:44.880 or of spontaneous movement. Such flower stalks closely resemble in 379 00:23:44.960 --> 00:23:48.880 structure those borne by sissas. This genus, belonging to the 380 00:23:48.920 --> 00:23:53.000 same family of the vitaser, produces well developed tendrils and 381 00:23:53.119 --> 00:23:57.039 on ordinary bunches of flowers, but there are no gradations 382 00:23:57.079 --> 00:24:01.440 between the two states. If the genus fit had been unknown, 383 00:24:01.599 --> 00:24:05.279 the boldest believer in the modification of species would never 384 00:24:05.319 --> 00:24:08.720 have surmised that the same individual plant at the same 385 00:24:08.799 --> 00:24:12.599 period of growth would have yielded every possible gradation between 386 00:24:12.720 --> 00:24:16.000 ordinary flower stalks for the support of the flowers and fruit, 387 00:24:16.440 --> 00:24:20.680 and tendrils use it exclusively for climbing. But the vine 388 00:24:20.720 --> 00:24:23.319 clearly gives us such a case, and it seems to 389 00:24:23.359 --> 00:24:26.839 me as striking and curious an instance of transition, as 390 00:24:26.880 --> 00:24:32.599 can well be conceived scissis discolor. The young shoots showed 391 00:24:32.680 --> 00:24:35.680 no more movement than can be accounted for by daily 392 00:24:35.759 --> 00:24:39.039 variations in the action of the light. The tendrils, however, 393 00:24:39.160 --> 00:24:42.559 revolved with much regularity following the sun, and in the 394 00:24:42.599 --> 00:24:46.039 plants observed by me, swept circles of about five inches 395 00:24:46.079 --> 00:24:50.039 in diameter. Five circles were completed in the following times 396 00:24:50.559 --> 00:24:54.599 four hours, forty five minutes, four hours, fifty minutes, four hours, 397 00:24:54.640 --> 00:24:58.119 forty five minutes, four hours, thirty minutes, and five hours 398 00:24:58.799 --> 00:25:01.359 the same tendril continue it needs to revolve during three 399 00:25:01.480 --> 00:25:04.480 or four days. The tendrils are from three and a 400 00:25:04.519 --> 00:25:07.559 half to five inches in length. They are formed of 401 00:25:07.599 --> 00:25:11.079 a long footstock bearing two short branches, which in old 402 00:25:11.160 --> 00:25:15.000 plants again bifurcate. The two branches are not of quite 403 00:25:15.160 --> 00:25:18.000 equal length, and as with the fine, the longer one 404 00:25:18.079 --> 00:25:21.640 has a scale at its base. The tendril stands vertically 405 00:25:21.720 --> 00:25:25.599 upwards the extremity of the shoot being bent abruptly downwards, 406 00:25:25.839 --> 00:25:28.400 and this position is probably a surface to plant by 407 00:25:28.440 --> 00:25:32.680 allowing the tendril to evolve freely and vertically. Both branches 408 00:25:32.720 --> 00:25:36.200 of the tendril, whilst young, are highly sensitive. A touch 409 00:25:36.240 --> 00:25:39.359 with a pencil so gentle as only just to move 410 00:25:39.440 --> 00:25:42.480 a tendril born at the end of a long flexible 411 00:25:42.519 --> 00:25:46.240 shoot sufficed to cause it to become perceptibly curved. In 412 00:25:46.400 --> 00:25:50.200 four or five minutes. It became straight again in rather 413 00:25:50.279 --> 00:25:53.920 above one hour. A loop of soft thread weighing one 414 00:25:54.000 --> 00:25:57.559 seventh of the grain nine point twenty five milligrams was 415 00:25:57.640 --> 00:26:01.039 thrice tried, and each time caused the tents to become curved. 416 00:26:01.359 --> 00:26:05.440 In thirty or forty minutes. Half this wave produced no effect. 417 00:26:06.240 --> 00:26:09.359 The long footstock is much less sensitive. For a slight 418 00:26:09.480 --> 00:26:13.200 rubbing produced no effect, although prolonged contact with the stick 419 00:26:13.319 --> 00:26:16.880 caused it to bend. The two branches are sensitive on 420 00:26:17.000 --> 00:26:20.240 all sides that they converge if touched on their inner sides, 421 00:26:20.279 --> 00:26:23.680 and diverged if touched on their outer sides. If a 422 00:26:23.720 --> 00:26:26.279 branch be touched at the same time with equal force 423 00:26:26.319 --> 00:26:29.960 on opposite sides, both sides are equally stimulated and there 424 00:26:30.039 --> 00:26:33.920 is no movement. Before examining this plant, I had preserved 425 00:26:33.960 --> 00:26:37.640 only tendrils which are

sensitive on one side alone, and these, 426 00:26:37.759 --> 00:26:41.000 when lightly pressed between the finger and thumb, become curved. 427 00:26:41.559 --> 00:26:44.880 But on thus pinching many times the tendrils of the scissus, 428 00:26:45.200 --> 00:26:48.799 no curvature ensued, and I falsely inferred at first that 429 00:26:48.880 --> 00:26:54.400 they were not at all sensitive. Scissus and Arcticus. The 430 00:26:54.519 --> 00:26:57.119 tendrils on a young plant were thick and straight, with 431 00:26:57.240 --> 00:27:00.799 tips a little curved. When their concave surfer uses were rubbed, 432 00:27:00.880 --> 00:27:03.440 and it was necessary to do this with some force, 433 00:27:03.799 --> 00:27:07.839 they very slowly became curved and subsequently straight again. They 434 00:27:07.880 --> 00:27:11.000 are therefore much less sensitive than those of the last species. 435 00:27:11.279 --> 00:27:14.519 But they made two revolutions following the sun rather more 436 00:27:14.599 --> 00:27:18.359 rapidly viz. In three hours, thirty minutes and four hours. 437 00:27:18.799 --> 00:27:25.000 The internodes do not revolve. Em Pelopsis heteraecia Virginian creeper. 438 00:27:25.759 --> 00:27:28.599 The internodes apparently do not move more than can be 439 00:27:28.599 --> 00:27:31.599 accounted for by the varying action of the light. The 440 00:27:31.680 --> 00:27:34.359 tendrils are from four to five inches in length, with 441 00:27:34.440 --> 00:27:37.680 the main stem sending off several lateral branches which have 442 00:27:37.759 --> 00:27:40.079 their tips curved, as may be seen in the upper 443 00:27:40.119 --> 00:27:45.319 figure Figure eleven. They exhibit no true spontaneous revolving movement, 444 00:27:45.680 --> 00:27:48.839 but turn, as was long ago observed by Andrew Knight, 445 00:27:49.119 --> 00:27:52.039 from the light to the dark. I have seen several 446 00:27:52.079 --> 00:27:55.039 trendrills move in less than twenty four hours through an 447 00:27:55.079 --> 00:27:57.880 angle up one hundred and eighty degrees to the dark 448 00:27:57.960 --> 00:28:00.440 side of a case in which a plant was placed, 449 00:28:00.799 --> 00:28:04.880 but the movement is sometimes much slower, the several lateral 450 00:28:04.920 --> 00:28:09.319 branches often moving independently of one another and sometimes irregularly 451 00:28:09.720 --> 00:28:13.920 without any apparent cause. These tendrils are less sensitive to 452 00:28:13.960 --> 00:28:17.559 a touch than any others. Observed by me by gentle 453 00:28:17.599 --> 00:28:20.359 but repeated rubbing with a twig, the lateral branches, but 454 00:28:20.480 --> 00:28:23.599 not the main stem, became, in the course of three 455 00:28:23.720 --> 00:28:27.160 or four hours, slightly curved, but they seemed to have 456 00:28:27.319 --> 00:28:31.680 hardly any power of again straightening themselves. The tendrils of 457 00:28:31.720 --> 00:28:34.920 a plant which had crawled over a large

box tree 458 00:28:35.279 --> 00:28:39.119 clasped several of the branches, but I have repeatedly seen 459 00:28:39.240 --> 00:28:43.519 that they will withdraw themselves after seizing a stick when 460 00:28:43.519 --> 00:28:46.480 they meet with a flat surface of wood or a wall, 461 00:28:46.759 --> 00:28:50.039 and this is evidently what they are adapted for. They 462 00:28:50.079 --> 00:28:53.960 turn all their branches towards it, and spreading them widely apart, 463 00:28:54.279 --> 00:28:58.079 bring their hooked tips laterally into contact with it. In 464 00:28:58.160 --> 00:29:02.279 affecting this, the several branches, after touching the surface often 465 00:29:02.480 --> 00:29:05.960 rise up, place themselves in a new position, and again 466 00:29:06.160 --> 00:29:09.799 come down into contact with it. So, in the course 467 00:29:09.839 --> 00:29:13.160 of about two days, after tendril has arranged its branches 468 00:29:13.200 --> 00:29:16.559 so as to press on any surface, the curved tips swell, 469 00:29:16.960 --> 00:29:20.559 become bright red, and form on their undersides the well 470 00:29:20.599 --> 00:29:24.119 known little discs or cushions with which they adhere firmly. 471 00:29:24.839 --> 00:29:27.720 In one case, the tips were slightly swollen in thirty 472 00:29:27.759 --> 00:29:30.839 eight hours after coming into contact with the brick. In 473 00:29:30.880 --> 00:29:34.480 another case they were considerably swollen in forty eight hours, 474 00:29:34.880 --> 00:29:37.880 and in an additional twenty four hours were firmly attached 475 00:29:37.880 --> 00:29:40.759 to a smooth board. And lastly, the tips of a 476 00:29:40.839 --> 00:29:44.039 younger tendril not only swelled but became attached to a 477 00:29:44.079 --> 00:29:48.880 stuccoed wall in forty two hours. These adhesive disks resemble, 478 00:29:49.039 --> 00:29:52.000 except in color and in being larger, those of the 479 00:29:52.039 --> 00:29:57.079 Bignonia capriolata when they were developed in contact with a 480 00:29:57.079 --> 00:30:00.759 ball of tow the fibers were separately env developed, but 481 00:30:00.920 --> 00:30:04.599 not in so effective a manner as by B. Capriolata. 482 00:30:05.480 --> 00:30:08.200 Discs are never developed, as far as I have seen, 483 00:30:08.240 --> 00:30:12.039 without the stimulus of at least temporary contact with some object. 484 00:30:12.640 --> 00:30:15.440 They are generally first formed on one side of the 485 00:30:15.480 --> 00:30:18.720 curved tip, the whole of which often becomes so much 486 00:30:18.799 --> 00:30:21.759 changed in appearance that a line of the original green 487 00:30:21.799 --> 00:30:26.599 tissue can be traced only along the concave surface. When, however, 488 00:30:26.680 --> 00:30:30.480 a tendril has clasped a cylindrical stick, an irregular rim 489 00:30:30.680 --> 00:30:34.599 or disc is sometimes formed along the inner surface, at 490 00:30:34.640 --> 00:30:37.799 some little distance from the curved tip. This was all 491 00:30:37.839 --> 00:30:42.000 to observed page seventy one by Mole. The discs consist 492 00:30:42.079 --> 00:30:47.200 of enlarged cells with smooth projecting hemispherical surfaces colored red. 493 00:30:47.680 --> 00:30:51.200 They are at first gorged with fluid see section given 494 00:30:51.279 --> 00:30:55.920 by Mole, page seventy, but ultimately become woody, as the 495 00:30:56.000 --> 00:30:59.920 discs soon adhere firmly to such smooth surfaces as plain 496 00:31:00.279 --> 00:31:04.119 or painted wood, or to the polished leaf of the ivy. 497 00:31:04.599 --> 00:31:08.920 This alone renders it probable that some cement is secreted, 498 00:31:09.000 --> 00:31:11.920 as has been asserted to be the case quoted by 499 00:31:12.000 --> 00:31:17.000 mole page seventy one by Malpingi. I removed a number 500 00:31:17.039 --> 00:31:19.680 of discs formed during the previous year from a stuccoed 501 00:31:19.720 --> 00:31:22.440 wall and left them during many hours in warm water 502 00:31:22.920 --> 00:31:26.839 diluted acetic acid and alcohol, but the attached grains of 503 00:31:26.920 --> 00:31:31.519 silex were not loosened. Immersion in sulfuric ether for twenty 504 00:31:31.519 --> 00:31:35.640 four hours loosened them much, but warmed essential oils. I 505 00:31:35.720 --> 00:31:39.920 tried oil of thyme and peppermint, completely released every particle 506 00:31:39.920 --> 00:31:43.279 of stone in the course of a few hours. This 507 00:31:43.319 --> 00:31:48.559 seems to prove that some resinous cement is secreted. The quantity, however, 508 00:31:48.680 --> 00:31:51.759 must be small, for when a plant ascended a thinly 509 00:31:51.799 --> 00:31:56.000 whitewashed wall, the discs adhered firmly to the whitewash, but 510 00:31:56.160 --> 00:31:59.480 as the cement never penetrated the thin layer, they were 511 00:31:59.519 --> 00:32:02.680 easily with drawn together with little scales of the whitewash. 512 00:32:03.119 --> 00:32:05.920 It must not be supposed that the attachment is affected 513 00:32:05.960 --> 00:32:11.119 exclusively by the cement, for the cellular outgrowth completely envelops 514 00:32:11.440 --> 00:32:16.279 every minute and irregular projection and insinuates itself into every crevice. 515 00:32:17.400 --> 00:32:19.960 A tendril which has not become attached to any body 516 00:32:20.079 --> 00:32:23.079 does not contract spirally and in the course of a 517 00:32:23.119 --> 00:32:26.519 week or two, shrinks into the finest thread, withers and 518 00:32:26.640 --> 00:32:30.720 drops off. An attached tendril, on the other hand, contracts 519 00:32:30.799 --> 00:32:34.799 spirally and thus becomes highly elastic, so that when the 520 00:32:34.839 --> 00:32:38.799 main footstock is pulled, the strain is distributed equally between 521 00:32:38.920 --> 00:32:42.279 all the attached discs. For a few days after the 522 00:32:42.319 --> 00:32:45.759 attachment of the disks,

the tendril remains weak and brittle, 523 00:32:46.000 --> 00:32:49.720 but it rapidly increases in thickness and acquires great strength. 524 00:32:50.799 --> 00:32:53.720 During the following winter, it ceases to live, but it 525 00:32:54.200 --> 00:32:56.880 is firmly in a dead state, both to its own 526 00:32:56.920 --> 00:33:00.920 stem and to the surface of attachment. In the accompany 527 00:33:00.960 --> 00:33:04.400 Young diagram Figure eleven, we see the difference between a 528 00:33:04.440 --> 00:33:07.880 tendril b some weeks after its attachment to a wall 529 00:33:08.240 --> 00:33:12.920 with one A from the same plant, fully grown but unattached. 530 00:33:13.720 --> 00:33:16.079 That the change in the nature of the tissues, as 531 00:33:16.160 --> 00:33:19.799 well as the spiral contraction are consequent on the formation 532 00:33:19.880 --> 00:33:23.240 of the discs, is well shown by any lateral branches 533 00:33:23.279 --> 00:33:26.480 which have not become attached. For these in a week 534 00:33:26.640 --> 00:33:29.440 or two weather and drop off in the same manner 535 00:33:29.480 --> 00:33:33.160 as does the whole tendril. If unattached. The gain and 536 00:33:33.240 --> 00:33:36.519 strength and durability in the tendril after its attachment is 537 00:33:36.680 --> 00:33:40.480 something wonderful. There are tendrils now adhering to my house 538 00:33:40.480 --> 00:33:43.160 which are still strong and have been exposed to the 539 00:33:43.160 --> 00:33:46.960 weather in a dead state for fourteen or fifteen years. 540 00:33:47.400 --> 00:33:51.160 One single lateral branch of a tendril, estimated to be 541 00:33:51.240 --> 00:33:54.720 at least ten years old, was still elastic and supported 542 00:33:54.759 --> 00:33:58.400 a weight of exactly two pounds. The whole tendril had 543 00:33:58.480 --> 00:34:02.279 five disc bearing branches of equal thickness and apparently of 544 00:34:02.359 --> 00:34:06.039 equal strength, so that after having been exposed during ten 545 00:34:06.119 --> 00:34:08.960 years to the weather, it could probably have resisted a 546 00:34:09.000 --> 00:34:16.480 strain of ten pounds. Sapandacia cardiosperma halicacabum. In this family, 547 00:34:16.599 --> 00:34:19.880 as in the last, the tentrils are modified flower peduncles. 548 00:34:20.360 --> 00:34:23.320 In the present plant, the two lateral branches of the 549 00:34:23.360 --> 00:34:26.800 main flower peduncle have been converted into a pair of tendrils, 550 00:34:27.199 --> 00:34:30.920 corresponding with the single flower tendril of the common vine. 551 00:34:31.440 --> 00:34:34.480 The main peduncle is thin, stiff, and from three to 552 00:34:34.519 --> 00:34:37.559 four and a half inches in length. Near the summit 553 00:34:37.639 --> 00:34:41.880 above two little bracts, it divides into three branches, the 554 00:34:41.920 --> 00:34:46.599 middle one divides and redivides and bears the flowers. Ultimately 555 00:34:46.639 --> 00:34:49.719 it grows half as long again as the two other 556 00:34:49.840 --> 00:34:54.079 modified branches. These latter are the tendrils. They are at 557 00:34:54.119 --> 00:34:57.000 first thicker and longer than the middle branch, but never 558 00:34:57.079 --> 00:35:00.920 become more than an inchine length to a point, and 559 00:35:01.039 --> 00:35:05.159 are flattened with the lower clasping surface distitute of hairs. 560 00:35:05.800 --> 00:35:09.880 At first they project straight up, but soon diverging spontaneously 561 00:35:09.960 --> 00:35:14.159 curled downwards so as to become symmetrically and elegantly hooked, 562 00:35:14.360 --> 00:35:17.800 as represented in the diagram. They are now whilst the 563 00:35:17.800 --> 00:35:21.000 flower buds are still small, ready for action. The two 564 00:35:21.239 --> 00:35:25.679 or three upper internodes, whilst young, steadily revolve. Those on 565 00:35:25.679 --> 00:35:28.400 one plant made two circles against the course of the 566 00:35:28.440 --> 00:35:32.119 sun in three hours twelve minutes. In a second plant, 567 00:35:32.159 --> 00:35:34.639 the same course was followed and the two circles were 568 00:35:34.679 --> 00:35:38.320 completed in three hours forty one minutes. In the third plant, 569 00:35:38.320 --> 00:35:41.199 the internodes followed the sun and made two circles in 570 00:35:41.280 --> 00:35:44.440 three hours forty seven minutes. The average rate of these 571 00:35:44.480 --> 00:35:48.119 six revolutions was one hour forty six minutes. The stems 572 00:35:48.239 --> 00:35:51.840 told no tendency to twine spirally round a support, but 573 00:35:51.920 --> 00:35:56.280 the allied tendril bearing genus Pallinia is said Mole page 574 00:35:56.320 --> 00:35:59.840 four to be a twina. The flower peduncles, which stand 575 00:36:00.079 --> 00:36:02.199 above the end of the shoot, are carried round and 576 00:36:02.280 --> 00:36:05.320 round by the revolving movement of the internodes, and when 577 00:36:05.320 --> 00:36:08.519 the stem is securely tied, the long and thin power 578 00:36:08.559 --> 00:36:12.840 peduncles themselves are seen to be incontinued and sometimes rapid 579 00:36:12.880 --> 00:36:16.159 movement from side to side. They sweep a wide space, 580 00:36:16.400 --> 00:36:20.440 but only occasionally revolve in a regular elliptical course by 581 00:36:20.480 --> 00:36:23.559 the combined movements of the internodes and peduncles. One of 582 00:36:23.599 --> 00:36:27.280 the two short hooked tendrils sooner or later catches hold 583 00:36:27.360 --> 00:36:30.079 of some twig or branch, and then it curls round 584 00:36:30.119 --> 00:36:34.519 and securely grasps it. These tendrils are, however, but slightly sensitive, 585 00:36:34.840 --> 00:36:37.760 for by rubbing their under surface only a slight movement 586 00:36:37.920 --> 00:36:41.519 is slowly produced. I hooked a tendril on to a twig, 587 00:36:41.800 --> 00:36:44.400 and in one hour forty five

minutes it was curved 588 00:36:44.440 --> 00:36:48.119 considerably inwards. In two hours thirty minutes it formed a ring, 589 00:36:48.440 --> 00:36:51.119 and in from five to six hours from being first hooked, 590 00:36:51.360 --> 00:36:55.800 it closely grasped the stick. A second tendril acted at 591 00:36:55.880 --> 00:36:58.559 nearly the same rate, but I observed one that took 592 00:36:58.599 --> 00:37:02.079 twenty four hours before curled twice round a thin twig. 593 00:37:03.039 --> 00:37:06.559 Tendrils which have caught nothing spontaneously curl up to a 594 00:37:06.599 --> 00:37:10.239 close helix after the interval of several days. Those which 595 00:37:10.239 --> 00:37:13.239 have curled round some object soon become a little thicker 596 00:37:13.280 --> 00:37:17.920 and tougher. The long and thin main peduncle, though spontaneously moving, 597 00:37:18.039 --> 00:37:21.679 is not sensitive and never clasps the support, nor does 598 00:37:21.719 --> 00:37:25.119 it ever contract spirally, though a contraction of this kind 599 00:37:25.159 --> 00:37:29.840 apparently would have been of service to the plant in climbing. Nevertheless, 600 00:37:29.880 --> 00:37:33.639 it climbs pretty well without this aid. The seed capsules 601 00:37:33.679 --> 00:37:37.079 low light are of enormous size, hence its English name 602 00:37:37.159 --> 00:37:40.039 of the loon vine, and as two or three are 603 00:37:40.079 --> 00:37:43.199 carried on the same peduncle, the tendrils rising close to 604 00:37:43.239 --> 00:37:46.320 them may be of service in preventing their being dashed 605 00:37:46.360 --> 00:37:49.239 to pieces by the wind. In the hot house, the 606 00:37:49.320 --> 00:37:53.440 tendrils served simply for climbing. The position of the tendrils 607 00:37:53.480 --> 00:37:58.119 alone suffices to show their homological nature. In two instances, 608 00:37:58.199 --> 00:38:02.440 one of the two tendrils produced a flower at its tip. This, however, 609 00:38:02.480 --> 00:38:06.599 did not prevent its acting properly and curling round a twig. 610 00:38:07.559 --> 00:38:10.320 In a third case, both lateral branches, which ought to 611 00:38:10.400 --> 00:38:13.639 have been modified with tendrils, produced flowers like the central 612 00:38:13.679 --> 00:38:18.599 branch and had quite lost their tendril structure. I have seen, 613 00:38:18.760 --> 00:38:22.559 but was not enabled carefully to observe only one other 614 00:38:22.679 --> 00:38:28.000 climbing sapadaceous plant, namely Pollinia. It was not in flower 615 00:38:28.159 --> 00:38:33.000 yet for long forked tendrils, so that Pollinia, with respect 616 00:38:33.079 --> 00:38:36.320 to its tendrils, appears to bear the same relation to 617 00:38:36.760 --> 00:38:44.280 Cardiospermum that Scissus does to Vitus plasifloraceae. After reading the 618 00:38:44.320 --> 00:38:47.199 discussion in facts given by Mole page forty seven on 619 00:38:47.280 --> 00:38:49.840 the nature of the tendrils in this family, no one 620 00:38:49.880 --> 00:38:53.400 can doubt that they are modified flower peduncles. The tendrils 621 00:38:53.400 --> 00:38:56.719 and the flower peduncles rise close side by side, and 622 00:38:56.800 --> 00:39:00.679 my son William E. Darwin made sketchusrny of their earliest 623 00:39:00.679 --> 00:39:04.679 state of development. In the hybrid p. Floribunda. The two 624 00:39:04.920 --> 00:39:08.719 organs appear at first as a single papilla, which gradually 625 00:39:08.760 --> 00:39:11.599 divides so that the tendril appears to be a modified 626 00:39:11.639 --> 00:39:15.320 branch of the flower peduncle. My son found one very 627 00:39:15.360 --> 00:39:19.519 young tendril surmounted by traces of floral organs exactly like 628 00:39:19.559 --> 00:39:22.159 those on the summit of the true flower peduncle at 629 00:39:22.159 --> 00:39:28.360 the same early age Passiflora gracillis. This well named elegant 630 00:39:28.440 --> 00:39:31.280 annual species differs from the other members of the group 631 00:39:31.360 --> 00:39:34.360 observed by me in that the young internodes have the 632 00:39:34.400 --> 00:39:38.280 power of revolving. It exceeds all the other climbing plants 633 00:39:38.320 --> 00:39:41.039 which I have examined in the rapidity of its movements, 634 00:39:41.360 --> 00:39:44.679 and all tendril bearers in the sensitiveness of the tendrils. 635 00:39:45.320 --> 00:39:48.599 The internode, which carries the upper active tendril, and which 636 00:39:48.760 --> 00:39:53.039 likewise carries one or two younger immature internodes, made three 637 00:39:53.159 --> 00:39:56.360 revolutions following the sun at an average rate of one 638 00:39:56.400 --> 00:40:00.440 hour four minutes. It then made the day becoming very hot, 639 00:40:00.760 --> 00:40:03.960 three other revolutions at an average rate of between fifty 640 00:40:04.000 --> 00:40:06.639 seven and fifty eight minutes, so that the average of 641 00:40:06.679 --> 00:40:10.400 all six revolutions was one hour one minute. The apex 642 00:40:10.400 --> 00:40:15.119 of the tendril describes elongated ellipses, sometimes near and sometimes broad, 643 00:40:15.159 --> 00:40:19.559 with their longer axis inclined in slightly different directions. The 644 00:40:19.599 --> 00:40:22.320 plant can send a thin upright stick by the aid 645 00:40:22.320 --> 00:40:24.719 of its tendrils, but the stem is too stiff for 646 00:40:24.840 --> 00:40:28.119 it to twines firely rounded even when not interfered with 647 00:40:28.239 --> 00:40:31.840 by the tendrils, these having been successively pinched off at 648 00:40:31.880 --> 00:40:36.199 an early age. When the stem is secured, the tendrils 649 00:40:36.199 --> 00:40:38.599 are seen to revolve in nearly the same manner and 650 00:40:38.639 --> 00:40:42.239 at the same rate as the internodes. The tendrils are 651 00:40:42.400 --> 00:40:45.800 very thin, delicate, and straight, with the exception of the tips,

652 00:40:46.000 --> 00:40:48.880 which are a little curved. They are from seven to 653 00:40:49.000 --> 00:40:53.039 nine inches in length. A half grown tendril is not sensitive, 654 00:40:53.360 --> 00:40:56.920 but when nearly full grown they are extremely sensitive. A 655 00:40:56.960 --> 00:40:59.760 single delicate touch on the concave surface of the tip 656 00:41:00.239 --> 00:41:03.000 soon caused one to curve, and in two minutes it 657 00:41:03.039 --> 00:41:06.599 formed an open helix. A loop of soft thread weighing 658 00:41:06.599 --> 00:41:11.079 one thirty second of a grain two point zero two milligrams, 659 00:41:11.280 --> 00:41:15.400 placed most gently on the tip thrice caused distinct curvature. 660 00:41:15.880 --> 00:41:20.360 A bent bit of thin platinum wire weighing one fiftieth 661 00:41:20.400 --> 00:41:24.599 of a grain one point two three milligrams twice produced 662 00:41:24.639 --> 00:41:27.800 the same effect, but this latter weight, when left suspended, 663 00:41:27.840 --> 00:41:32.119 did not suffice to cause a permanent curvature. These trials 664 00:41:32.119 --> 00:41:34.360 were made under a bell glass so that the loops 665 00:41:34.360 --> 00:41:37.119 of thread and wire were not agitated by the wind. 666 00:41:37.920 --> 00:41:41.000 The movement after a touch is very rapid. I took 667 00:41:41.079 --> 00:41:43.639 hold of the lower part of several tendrils and then 668 00:41:43.719 --> 00:41:46.840 touched their concave tips with a thin twig and watched 669 00:41:46.840 --> 00:41:50.320 them carefully through a lens. The tips evidently began to 670 00:41:50.360 --> 00:41:55.159 bend after the following intervals thirty one, twenty five, thirty two, 671 00:41:55.440 --> 00:42:00.000 thirty one, twenty eight, thirty nine, thirty one and thirty seconds, 672 00:42:00.599 --> 00:42:03.519 so that the movement was generally perceptible in half a 673 00:42:03.599 --> 00:42:06.719 minute after a touch, but on one occasion it was 674 00:42:06.800 --> 00:42:11.719 distinctly visible in twenty five seconds. One of the tendrils 675 00:42:11.719 --> 00:42:14.559 which thus became bent in thirty one seconds, had been 676 00:42:14.599 --> 00:42:17.840 touched two hours previously and had coiled into a helix, 677 00:42:18.239 --> 00:42:21.079 so that in this interval it had straightened itself and 678 00:42:21.159 --> 00:42:26.079 had perfectly recovered its irritability. To ascertain how often the 679 00:42:26.119 --> 00:42:29.320 same tendril would become curved when touched, I placed a 680 00:42:29.360 --> 00:42:32.239 plant in my study, which, from being cooler than the 681 00:42:32.280 --> 00:42:35.880 hot house, was not very favorable for the experiment. The 682 00:42:35.960 --> 00:42:38.719 extremity was gently rubbed four or five times with a 683 00:42:38.760 --> 00:42:41.360 thin stick and this was done as often as it 684 00:42:41.400 --> 00:42:44.199 was observed to have become nearly straight again after having

685 00:42:44.199 --> 00:42:46.920 been in action, and in the course of fifty four 686 00:42:46.960 --> 00:42:50.639 hours it answered to the stimulus twenty one times, becoming 687 00:42:50.719 --> 00:42:54.480 each time hooked or spiral. On the last occasion, however, 688 00:42:54.519 --> 00:42:58.239 the movement was very slight, and soon afterwards permanent spiral 689 00:42:58.320 --> 00:43:02.280 contraction commenced. No trials were made during the night, so 690 00:43:02.320 --> 00:43:05.119 that the tendril would perhaps have answered a greater number 691 00:43:05.199 --> 00:43:08.400 of times to the stimulus, though on the other hand, 692 00:43:08.519 --> 00:43:11.719 from having no rest, it might have become exhausted from 693 00:43:11.760 --> 00:43:16.079 so many quickly repeated efforts. I repeated the experiment made 694 00:43:16.119 --> 00:43:19.039 on the itchin of Cistus, and placed several plants of 695 00:43:19.039 --> 00:43:22.320 this passive flora so close together that their tendrils were 696 00:43:22.360 --> 00:43:27.400 repeatedly dragged over each other, but no curvature ensued. I 697 00:43:27.559 --> 00:43:31.360 likewise repeatedly flirted small drops of water from a brush 698 00:43:31.400 --> 00:43:35.159 on many tendrils, and syringed others so violently that the 699 00:43:35.199 --> 00:43:38.599 whole tendril was dashed about, but they never became curved. 700 00:43:39.360 --> 00:43:41.880 The impact from the drops of water was felt far 701 00:43:41.960 --> 00:43:45.280 more distinctly on my hand than that from the loops 702 00:43:45.320 --> 00:43:48.679 of thread weighing one thirty second of a grain when 703 00:43:48.719 --> 00:43:51.880 allowed to fall on it from a height, and these loops, 704 00:43:51.880 --> 00:43:54.639 which caused the tendrils to become curved, have been placed 705 00:43:54.679 --> 00:43:57.559 most gently on them. Hence it is clear that the 706 00:43:57.679 --> 00:44:00.559 tendrils either have become habituated to the touch of other 707 00:44:00.639 --> 00:44:03.599 tendrils and drops of rain, or they were from the 708 00:44:03.639 --> 00:44:07.920 first rensured sensitive only to prolonged the excessively slight pressure 709 00:44:07.920 --> 00:44:11.679 of solid objects, with the exclusion of that from other tendrils. 710 00:44:12.320 --> 00:44:14.760 To show the difference in the kind of sensitiveness in 711 00:44:14.800 --> 00:44:17.559 different plants, and likewise to show the force of the 712 00:44:17.599 --> 00:44:20.519 syringe used, I may add that the lightest jet from 713 00:44:20.559 --> 00:44:24.000 it instantly caused the leaves of a mimosa to close, 714 00:44:24.360 --> 00:44:26.840 whereas the loop of thread rain one thirty seconds of 715 00:44:26.840 --> 00:44:29.679 a grain, when rolled into a ball and placed gently 716 00:44:29.760 --> 00:44:32.199 on the glands at the basis of the leaflets of 717 00:44:32.239 --> 00:44:39.039 the mimosa, caused no action. Passiflora punctata the internats do 718 00:44:39.159 --> 00:44:43.039 not move, but the tendrils revolve regularly. A half grown 719 00:44:43.079 --> 00:44:46.719 and very sensitive tendril made three revolutions opposed to the 720 00:44:46.760 --> 00:44:49.679 course of the sun in three hours five minutes. Two 721 00:44:49.760 --> 00:44:53.360 hours forty minutes and two hours fifty minutes. Perhaps it 722 00:44:53.440 --> 00:44:57.119 might have traveled more quickly when nearly fully grown a 723 00:44:57.199 --> 00:44:59.880 plant was placed in front of a window, and, as 724 00:45:00.079 --> 00:45:03.039 with twining stems, the light accelerated the movement of the 725 00:45:03.079 --> 00:45:05.760 tendril in one direction and retarded it in the other, 726 00:45:06.360 --> 00:45:09.480 the semicircle towards the light being performed in one instance 727 00:45:09.599 --> 00:45:12.920 in fifteen minutes less time, and in a second instance 728 00:45:13.039 --> 00:45:16.119 in twenty minutes less time than that required by the 729 00:45:16.119 --> 00:45:19.840 semicircle towards the dark end of the room. Considering the 730 00:45:19.880 --> 00:45:23.320 extreme tenuity of these tendrils, the action of a light 731 00:45:23.360 --> 00:45:26.800 on them is remarkable. The tendrils are long and, as 732 00:45:27.000 --> 00:45:30.679 just stated, very thin, with the tip slightly curved or hooked. 733 00:45:31.199 --> 00:45:34.440 The concave side is extremely sensitive to a touch, even 734 00:45:34.480 --> 00:45:37.880 a single touch, causing it to curl inwards. It subsequently 735 00:45:37.920 --> 00:45:41.599 straightened itself and was again ready to act. A loop 736 00:45:41.639 --> 00:45:44.559 of soft thread weighing one fourteenth of a grain four 737 00:45:44.599 --> 00:45:48.199 point six five milligrams caused the extreme tip to bend. 738 00:45:48.719 --> 00:45:51.159 Another time I tried to hang the same little loop 739 00:45:51.199 --> 00:45:54.400 on an incline tendril, but three times it slid off. 740 00:45:54.760 --> 00:45:58.199 Yet this extraordinarily slight degree friction sufficed to make the 741 00:45:58.239 --> 00:46:03.239 tip curl. Tendril, though so sensitive, does not move very 742 00:46:03.280 --> 00:46:08.079 quickly after a touch, no conspicuous movement being observable until 743 00:46:08.159 --> 00:46:11.320 five or ten minutes had elapsed. The convex side of 744 00:46:11.320 --> 00:46:13.920 the tip is not sensitive to a touch, nor to 745 00:46:14.000 --> 00:46:17.480 a suspended loop of thread. On one occasion I observed 746 00:46:17.519 --> 00:46:21.079 a tendril revolving with the convex side of the tip forwards, 747 00:46:21.320 --> 00:46:23.840 and in consequence it was not able to clasp the 748 00:46:23.920 --> 00:46:27.760 stick against which it scraped, whereas tendrils revolving with the 749 00:46:27.800 --> 00:46:31.280 concave side forward promptly sees any object in their path. 750 00:46:32.440 --> 00:46:38.480 Passiflora

quadrangularis. This is a various distinct species. The tendrils 751 00:46:38.480 --> 00:46:41.480 are thick, long, and stiff, and they are sensitive to 752 00:46:41.519 --> 00:46:45.079 a touch only on the concave surface towards the extremity. 753 00:46:45.679 --> 00:46:47.719 When a stick was placed so that the middle of 754 00:46:47.719 --> 00:46:51.239 the tendril came into contact with it, no curvature ensued. 755 00:46:51.800 --> 00:46:54.800 In the hot house, a tendril made two revolutions, each 756 00:46:54.840 --> 00:46:57.480 in two hours twenty two minutes. In a cool room, 757 00:46:57.960 --> 00:47:00.719 one was completed in three hours and the second in 758 00:47:00.800 --> 00:47:04.760 four hours. The internodes do not revolve, nor do those 759 00:47:04.760 --> 00:47:10.400 of the hybrid P. Floribunda Taxonia mannakata. Here again the 760 00:47:10.440 --> 00:47:14.079 internodes do not revolve. The tendrils are moderately thin and long. 761 00:47:14.400 --> 00:47:17.159 One made in narrower lips in five hours twenty minutes, 762 00:47:17.360 --> 00:47:19.480 and the next day a broadly lips in five hours 763 00:47:19.519 --> 00:47:23.519 seven minutes. The extremity, being lightly rubbed on the concave surface, 764 00:47:23.559 --> 00:47:27.599 became just perceptibly curved in seven minutes, distinctly in ten minutes, 765 00:47:27.639 --> 00:47:30.960 and hooked in twenty minutes. We have seen that the 766 00:47:31.000 --> 00:47:35.239 tendrils in the last three families, namely the Vitasia, Sapandacia, 767 00:47:35.400 --> 00:47:40.360 and Passifloracia, are modified flower peduncles. This is likewise the case, 768 00:47:40.440 --> 00:47:44.400 according to Decandole, as quoted by More, with the tendrils 769 00:47:44.440 --> 00:47:48.719 of Brunetia one of the Polygonaca, in two or three 770 00:47:48.719 --> 00:47:52.280 species of Modecca one of the papaye Cia. The tendrils, 771 00:47:52.360 --> 00:47:56.320 as I hear from Professor Oliver, occasionally bear flowers and fruit, 772 00:47:56.679 --> 00:48:00.920 so that they are axial in their nature. The spiral 773 00:48:01.039 --> 00:48:05.880 contraction of tendrils, this movement which shortens the tendrils and 774 00:48:05.960 --> 00:48:09.280 renders them elastic, commences in half a day or in 775 00:48:09.320 --> 00:48:12.639 a day or two after their extremities have caught some object. 776 00:48:13.199 --> 00:48:15.840 There is no such movement in any leaf climber, with 777 00:48:15.920 --> 00:48:18.119 the exception of an occasional trace of it in the 778 00:48:18.119 --> 00:48:23.239 petioles of Tropalium tricholorum. On the other hand, the tendrils 779 00:48:23.280 --> 00:48:27.000 of all tendril bearing plants contract spirally after they have 780 00:48:27.119 --> 00:48:32.639 caught an object, with the following exceptions. Firstly, Cordalus clavicalata, 781 00:48:33.159 --> 00:48:36.920 but then this plant might be called a leaf climber. Secondly, 782 00:48:36.960 --> 00:48:41.760 and thirdly Bignonia anguis with its close allies and Cardiospermum, 783 00:48:42.280 --> 00:48:45.519 but their tendrils are so short that their contraction could 784 00:48:45.519 --> 00:48:51.599 hardly occur and would be quite superfluous. Fourthly, Similee asphera 785 00:48:51.760 --> 00:48:55.440 offers a more marked exception, as its tendrils are moderately long. 786 00:48:56.039 --> 00:48:59.599 The tendrils of Dicentra, whilst the plant is young, are short, 787 00:48:59.639 --> 00:49:04.000 and a detachment only becomes slightly flectuous. In older plants 788 00:49:04.039 --> 00:49:07.920 they are longer, and then they contract spirally. I have 789 00:49:08.000 --> 00:49:11.320 seen no other exceptions to the rule that tendrils, after 790 00:49:11.400 --> 00:49:16.800 clasping with their extremities of support undergo spiral contraction, when, however, 791 00:49:16.840 --> 00:49:18.920 the tendril of a plant of which the stem is 792 00:49:18.960 --> 00:49:23.880 immovably fixed catches some fixed object. It does not contract 793 00:49:23.920 --> 00:49:28.360 simply because it cannot. This, however, rarely occurs. In the 794 00:49:28.400 --> 00:49:31.639 common pee, the lateral branches alone contract and not the 795 00:49:31.679 --> 00:49:35.400 central stem, and with most plants, such as the vine 796 00:49:35.440 --> 00:49:41.280 Passiflora bryoni, the basal portion never forms a spire. I 797 00:49:41.320 --> 00:49:45.239 have said that in Corridalis claviculata, the end of the 798 00:49:45.320 --> 00:49:48.840 leaf or tendril, for this part may be indifferently called 799 00:49:48.960 --> 00:49:53.400 so does not contract into a spire. The branchlets, however, 800 00:49:53.519 --> 00:49:57.400 after they have wound round thin twigs, become deeply sinuous 801 00:49:57.480 --> 00:50:01.719 or zigzag. Moreover, the whole end of the petiole or tendril, 802 00:50:01.800 --> 00:50:05.800 if it ceases nothing, bends after a time abruptly downwards 803 00:50:05.800 --> 00:50:09.400 and inwards, showing that its outer surface has gone on 804 00:50:09.679 --> 00:50:13.760 growing after the inner surface has ceased to grow. That 805 00:50:13.920 --> 00:50:17.440 growth is the chief cause of the spiral contraction of tendrils, 806 00:50:17.480 --> 00:50:21.119 may be safely admitted, as shown by the recent researches 807 00:50:21.159 --> 00:50:24.800 of H. Devrees. I will, however, add one little fact 808 00:50:24.840 --> 00:50:28.760 in support of this conclusion. If the short, nearly straight 809 00:50:28.800 --> 00:50:33.440 portion of an attached tendril of Passiflora gracillus, and as 810 00:50:33.480 --> 00:50:37.800 I believe, of other tendrils between the opposed spired be examined, 811 00:50:38.239 --> 00:50:41.519 it will be found to be transversely wrinkled in a 812 00:50:41.559 --> 00:50:45.880 conspicuous manner on the outside, and this would naturally follow 813 00:50:45.960 --> 00:50:48.920 if the outer side had

grown more than the inner side, 814 00:50:49.159 --> 00:50:53.199 this part being at the same time forcibly prevented from 815 00:50:53.239 --> 00:50:57.519 becoming curved. So while the whole outer surface of a 816 00:50:57.559 --> 00:51:03.639 spirally round tendril becomes rinkled if it be pulled straight. Nevertheless, 817 00:51:03.679 --> 00:51:07.039 as the contraction travels from the extremity of a tendril 818 00:51:07.199 --> 00:51:09.880 after it has been stimulated by contact with the support, 819 00:51:10.320 --> 00:51:13.960 down to the base, I cannot avoid doubting, from reasons 820 00:51:14.000 --> 00:51:17.000 presently to be given, whether the whole effect ought to 821 00:51:17.039 --> 00:51:21.880 be attributed to growth. An unattached tendril rolls itself up 822 00:51:21.960 --> 00:51:25.480 into a flat helix, as in the case of cardiospermum, 823 00:51:25.679 --> 00:51:29.280 if the contraction commences at the extremity and is quite regular, 824 00:51:29.960 --> 00:51:32.840 But if the continued growth of the outer surface is 825 00:51:32.880 --> 00:51:36.199 a little lateral, or if the process begins near the base, 826 00:51:36.559 --> 00:51:40.239 the terminal portion cannot be rolled up within the basal portion, 827 00:51:40.679 --> 00:51:43.880 and the tendril then forms a more or less open spire. 828 00:51:44.639 --> 00:51:47.480 A similar result follows if the extremity has caught some 829 00:51:47.639 --> 00:51:51.480 object and is thus held fast. The tendrils of many 830 00:51:51.559 --> 00:51:54.880 kinds of plants, if they catch nothing, contract after an 831 00:51:54.920 --> 00:51:58.199 interval of several days or weeks into a spire. But 832 00:51:58.480 --> 00:52:01.559 in these cases the movement takes place after the tendril 833 00:52:01.599 --> 00:52:05.519 has lost its revolving power and hangs down. It has 834 00:52:05.639 --> 00:52:09.440 also then partly or wholly lost its sensibility, so that 835 00:52:09.480 --> 00:52:13.599 this movement can be of no use. The spiral contraction 836 00:52:13.800 --> 00:52:17.119 of unattached tendrils is a much slower process than that 837 00:52:17.199 --> 00:52:21.039 of attached ones. Young tendrils which have caught a support 838 00:52:21.119 --> 00:52:24.440 and are spirally contracted may constantly be seen on the 839 00:52:24.480 --> 00:52:29.400 same stem with the much older, unattached and uncontracted tendrils. 840 00:52:29.760 --> 00:52:32.639 In the Echinocistus, I have seen a tendril with the 841 00:52:32.639 --> 00:52:37.320 two lateral branches encircling twigs and contracted into beautiful spires, 842 00:52:37.679 --> 00:52:41.199 whilst the main branch, which had caught nothing, remained for 843 00:52:41.320 --> 00:52:45.199 many days straight. In this plant, I once observed a 844 00:52:45.280 --> 00:52:48.360 main branch after it had caught a stick, becomes spirally 845 00:52:48.400 --> 00:52:53.960 flectuous in seven hours and spirally contracted in eighteen hours. Generally, 846 00:52:54.000 --> 00:52:58.079 the tendrils of the Echinocistis yeend to contract in twelve 847 00:52:58.079 --> 00:53:01.679 hours to twenty four hours after catching some objects, whilst 848 00:53:01.800 --> 00:53:05.239 unattrached tendrils do not begin to contract until two or 849 00:53:05.320 --> 00:53:09.199 three or even more days after all revolving movement has ceased. 850 00:53:10.079 --> 00:53:14.519 A full grown tendril of Passiflora quadrangularis, which had caught 851 00:53:14.599 --> 00:53:17.280 a stick, began in eight hours to contract, and in 852 00:53:17.320 --> 00:53:21.199 twenty four hours formed several spires. A young tendril, only 853 00:53:21.239 --> 00:53:24.599 two thirds grown, showed the first trace of contraction in 854 00:53:24.679 --> 00:53:27.840 two days after clasping a stick, and in two more 855 00:53:27.920 --> 00:53:31.840 days formed several spires. It appears, therefore, that the contraction 856 00:53:31.960 --> 00:53:34.840 does not begin until the tendril is grown to nearly 857 00:53:34.920 --> 00:53:38.440 its full length. Another young tendril of about the same 858 00:53:38.519 --> 00:53:42.000 age and length as the last, did not catch any object. 859 00:53:42.400 --> 00:53:45.599 It acquired its full length in four days. In six 860 00:53:45.679 --> 00:53:49.119 additional days it first became fectuous, and in two more 861 00:53:49.199 --> 00:53:53.639 days formed one complete spire. This first spire was formed 862 00:53:53.639 --> 00:53:56.639 towards the basal end, and the contraction steadily but slowly 863 00:53:56.679 --> 00:53:59.880 progressed towards the apex. But the whole was not close. 864 00:54:00.079 --> 00:54:02.920 We wound up into a spire until twenty one days 865 00:54:02.960 --> 00:54:06.880 had elapsed from the first observation, that is, until seventeen 866 00:54:07.000 --> 00:54:09.519 days after the tendril had grown to its full length. 867 00:54:10.480 --> 00:54:13.480 The spiral contraction of tendrils is quite independent of their 868 00:54:13.519 --> 00:54:17.519 power of spontaneously revolving, for it occurs in tendrils such 869 00:54:17.519 --> 00:54:23.280 as those of Lathyrus grandiflorus and Ampelopsis hederaciae, which do 870 00:54:23.440 --> 00:54:26.960 not revolve. It is not necessarily related to the curling 871 00:54:27.039 --> 00:54:29.639 of the tips around a support, as we see with 872 00:54:29.719 --> 00:54:34.119 the Ampelopsis and the Bignonia crapriolata, in which the development 873 00:54:34.199 --> 00:54:39.360 of adherent disks suffices to cause spiral contraction. Yet in 874 00:54:39.400 --> 00:54:42.679 some cases this contraction seems connected with the curling or 875 00:54:42.719 --> 00:54:46.239 clasping movement due to contact with the support, for not 876 00:54:46.360 --> 00:54:49.159 only does it soon follow this act, but the contraction 877 00:54:49.280 --> 00:54:52.960 generally begins to close to the curled

extremity and travel 878 00:54:53.039 --> 00:54:56.920 downwards to the base. If, however, a tendril be very slack, 879 00:54:57.000 --> 00:55:01.480 the whole length almost simultaneously becomes at first reflectuous and 880 00:55:01.559 --> 00:55:06.280 then spiral again. The tendrils of some few plants never 881 00:55:06.360 --> 00:55:11.199 contract spirally unless they have first seized hold of some object. 882 00:55:11.800 --> 00:55:15.199 If they catch nothing, they hang down, remaining straight until 883 00:55:15.199 --> 00:55:18.039 they wither and drop off. This is the case with 884 00:55:18.119 --> 00:55:21.760 the tendrils of Bignonia, which consist of modified leaves, and 885 00:55:21.880 --> 00:55:24.880 with those of three genera of the Tasia, which are 886 00:55:24.880 --> 00:55:28.920 modified flower peduncles. But in the great majority of cases, 887 00:55:29.039 --> 00:55:32.280 tendrils which have never come in contact with any object 888 00:55:32.679 --> 00:55:36.960 after a time contracts spirally. All these facts, taken together, 889 00:55:37.039 --> 00:55:39.400 show that the act of clasping the support and the 890 00:55:39.440 --> 00:55:42.440 spiral contraction of the whole length of the tendril are 891 00:55:42.519 --> 00:55:47.960 phenomena not necessarily connected. The spiral contraction which ensues after 892 00:55:47.960 --> 00:55:50.920 a tendril has caught a support is of high service 893 00:55:50.960 --> 00:55:55.159 to the plant, whence its almost universal occurrence with species 894 00:55:55.199 --> 00:55:59.480 belonging to widely different orders. When a shoot is inclined 895 00:55:59.519 --> 00:56:02.079 and its ten undil has caught an object above, the 896 00:56:02.119 --> 00:56:06.119 spiral contraction drags up the chute. When the shoot is upright, 897 00:56:06.199 --> 00:56:08.760 the growth of the stem at the tendrils have seized 898 00:56:08.800 --> 00:56:12.000 some object above or leave its slack were not the 899 00:56:12.039 --> 00:56:15.719 spiral contraction which draws up the stem as it increases 900 00:56:15.760 --> 00:56:18.840 in length. Thus there is no waste of growth and 901 00:56:18.920 --> 00:56:23.039 the stretched stem ascends by the shortest course. When a 902 00:56:23.119 --> 00:56:27.800 terminal branchlet of the tendril of cobair catches a stick, 903 00:56:28.119 --> 00:56:31.679 we have seen how well the spiral contraction successfully brings 904 00:56:31.719 --> 00:56:35.320 the other branchlets, one after the other into contact with 905 00:56:35.440 --> 00:56:38.519 the stick, until the whole tendril grasps it in an 906 00:56:38.599 --> 00:56:43.159 inextricable knot when the tendril has caught a yielding object. 907 00:56:43.440 --> 00:56:46.639 This is sometimes enveloped and still further secured by the 908 00:56:46.719 --> 00:56:51.519 spiral folds, as I have seen with Passiflora quadrangularis. But 909 00:56:51.599 --> 00:56:55.760 this action is of little importance. A far

more important 910 00:56:55.760 --> 00:56:58.719 service rendered by the spiral contraction of the tendrils is 911 00:56:58.719 --> 00:57:02.800 that they are thus made highly elastic. As before remarked 912 00:57:02.880 --> 00:57:06.800 under amplopsis. The strain is thus distributed equally between the 913 00:57:06.840 --> 00:57:10.800 several attached branches, and this renders the whole far stronger 914 00:57:10.920 --> 00:57:14.719 than it otherwise would be, as the branches cannot break separately. 915 00:57:15.440 --> 00:57:19.119 It is this elasticity which protects both branched and simple 916 00:57:19.199 --> 00:57:22.639 tendrils from being torn away from their supports during storm weather. 917 00:57:23.480 --> 00:57:26.280 I have more than once gone on purpose during a 918 00:57:26.320 --> 00:57:30.800 gale to watch a brione growing in unexposed hedge with 919 00:57:30.880 --> 00:57:34.159 its tendrils attached to the surrounding bushes, and as the 920 00:57:34.239 --> 00:57:37.079 thick and thin branches are tossed to and fro by 921 00:57:37.119 --> 00:57:40.760 the wind, the tendrils, had they not been excessively elastic, 922 00:57:41.000 --> 00:57:44.760 would instantly have been torn off and the plant thrown prostate. 923 00:57:45.360 --> 00:57:48.480 But as it was, the bryony safely rowed out the 924 00:57:48.519 --> 00:57:51.239 gale like a ship with two anchors down and with 925 00:57:51.320 --> 00:57:53.920 a long range of cable ahead to serve as a 926 00:57:53.920 --> 00:57:58.280 spring as she surges to the storm. When an unattached 927 00:57:58.360 --> 00:58:03.079 tendril contracts firally, the spire always runs in the same 928 00:58:03.119 --> 00:58:06.559 direction from tip to base. A tendril, on the other hand, 929 00:58:06.719 --> 00:58:10.280 which has caught a support by its extremity, although the 930 00:58:10.320 --> 00:58:14.480 same side is concave from end to end, invariably becomes 931 00:58:14.480 --> 00:58:17.679 twisted in one part in one direction and in another 932 00:58:17.760 --> 00:58:21.880 part in the opposite direction, the oppositely turned spires being 933 00:58:21.920 --> 00:58:26.559 separated by a short straight portion. This curious and symmetrical 934 00:58:26.559 --> 00:58:29.519 structure has been noticed by several botanists, but has not 935 00:58:29.599 --> 00:58:34.320 been sufficiently explained. It occurs without exception with all tendrils, 936 00:58:34.480 --> 00:58:38.039 which after catching an object contracts spirally, but is of 937 00:58:38.119 --> 00:58:42.440 course most conspicuous in the longer tendrils. It never occurs 938 00:58:42.480 --> 00:58:45.880 with uncaught tendrils, and when this appears to have occurred, 939 00:58:45.920 --> 00:58:49.159 it will be found that the tendril had origionally seized 940 00:58:49.239 --> 00:58:53.719 some object and had afterwards been torn free. Commonly, all 941 00:58:53.760 --> 00:58:57.039 the spires at one end of an attached tendril run 942 00:58:57.159 --> 00:59:00.400 in one direction, and all those at the other end 943 00:59:00.519 --> 00:59:04.000 in the opposite direction, with a single short straight portion 944 00:59:04.159 --> 00:59:07.159 in the middle. But I have seen a tendril with 945 00:59:07.199 --> 00:59:11.679 spires alternately turning five times in opposite directions, with straight 946 00:59:11.760 --> 00:59:15.800 pieces between them, and M beyond has seen seven or 947 00:59:15.840 --> 00:59:20.199 eight such alternations. Whether the spires turn once or more 948 00:59:20.239 --> 00:59:23.559 than once in opposite directions, there are as many turns 949 00:59:23.599 --> 00:59:26.960 in the one direction as in the other. For instance, 950 00:59:27.079 --> 00:59:31.159 I gathered ten attached tendrils of bryany, the longest with 951 00:59:31.400 --> 00:59:34.760 thirty three and the shortest with only eight spiral turns, 952 00:59:35.199 --> 00:59:37.320 And the number of turns in the one direction was 953 00:59:37.360 --> 00:59:40.519 in every case the same within one as in the 954 00:59:40.559 --> 00:59:44.800 opposite direction. The explanation of this curious little fact is 955 00:59:44.840 --> 00:59:48.599 not difficult. I will not attempt any geometrical reasoning, but 956 00:59:48.679 --> 00:59:52.280 will give only a practical illustration. In doing this, I 957 00:59:52.280 --> 00:59:54.800 shall first have to allude to a point which was 958 00:59:54.880 --> 00:59:58.920 almost passed over when treating of twining plants. If we 959 00:59:59.000 --> 01:00:02.519 hold in our left hand hand a bundle of parallel strings, 960 01:00:02.840 --> 01:00:06.199 we can with our right hand turn these round and round, 961 01:00:06.440 --> 01:00:10.000 thus imitating the revolving movement of a twining plant, and 962 01:00:10.079 --> 01:00:13.760 the strings do not become twisted. But if we hold 963 01:00:13.840 --> 01:00:16.280 at the same time a stick in our left hand 964 01:00:16.639 --> 01:00:19.840 in such a position that if the strings become spirally 965 01:00:19.880 --> 01:00:24.800 turned round it, they will inevitably become twisted. Hence, a 966 01:00:24.880 --> 01:00:28.480 straight colored line painted along the internodes of a twining 967 01:00:28.559 --> 01:00:32.599 plant before it has wound round a support becomes twisted 968 01:00:32.719 --> 01:00:36.280 or spiral after it has wound round. I painted a 969 01:00:36.360 --> 01:00:41.639 red line on the straight internodes of a humulus Mecania, cyropagia, 970 01:00:42.039 --> 01:00:46.440 convolvolus and phasiolus, and saw it become twisted as the 971 01:00:46.519 --> 01:00:50.760 plant wound round a stick. It is possible that the 972 01:00:50.800 --> 01:00:53.880 stems of some plants, by spontaneously turning on their own 973 01:00:53.920 --> 01:00:56.960 axis at the proper rate and in the proper direction, 974 01:00:57.239 --> 01:01:01.039 might avoid becoming twisted, but I have seen no

such case. 975 01:01:02.199 --> 01:01:05.599 In the above illustration, the parallel strings were wound around 976 01:01:05.800 --> 01:01:08.800 a stick, but this is by no means necessary, for 977 01:01:08.920 --> 01:01:12.360 if wound into a hollow coil, as can be done 978 01:01:12.360 --> 01:01:15.159 with a narrow slip of elastic paper, there is the 979 01:01:15.199 --> 01:01:19.760 same well twisting of the axis. When therefore, a very 980 01:01:20.039 --> 01:01:23.920 tendril coils itself into a spire, it must either become 981 01:01:23.960 --> 01:01:27.719 twisted along its whole length, and this never occurs, or 982 01:01:27.760 --> 01:01:31.159 the free extremity must turn round as many times as 983 01:01:31.199 --> 01:01:35.159 these spires are formed. It was hardly necessary to observe 984 01:01:35.239 --> 01:01:38.199 this fact, but I did so by fixing little paper 985 01:01:38.280 --> 01:01:42.119 veins to the extreme points of the tendrils of Echinocystus 986 01:01:42.159 --> 01:01:46.519 and Passiflora quadrangularis. And as the tendril contracted itself into 987 01:01:46.559 --> 01:01:51.679 successive spires, the veins slowly revolved. I can now understand 988 01:01:51.760 --> 01:01:54.760 the meaning of the spires being invariably turned in opposite 989 01:01:54.800 --> 01:01:59.119 directions in tendrils which, from having caught some object, are 990 01:01:59.159 --> 01:02:03.400 fixed at both ends. Let us suppose a caught tendril 991 01:02:03.440 --> 01:02:06.159 to make thirty spiral turns, all in the same direction. 992 01:02:06.800 --> 01:02:09.920 The inevitable result would be that it would become twisted 993 01:02:09.960 --> 01:02:13.239 thirty times on its own axis. This twisting would not 994 01:02:13.280 --> 01:02:16.679 only require considerable force, but as I know by trial, 995 01:02:16.960 --> 01:02:20.360 would burst the tendril before the thirty turns were completed. 996 01:02:21.079 --> 01:02:25.000 Such cases never really occur, for as already stated, when 997 01:02:25.039 --> 01:02:28.000 a tendril has caught a support and is spirally contracted, 998 01:02:28.239 --> 01:02:30.840 there are always as many turns in one direction as 999 01:02:30.840 --> 01:02:33.239 in the other, so that the twisting of the axis 1000 01:02:33.239 --> 01:02:36.280 in the one direction is exactly compensated by the twisting 1001 01:02:36.320 --> 01:02:39.519 in the opposite direction. We can further see how the 1002 01:02:39.559 --> 01:02:42.920 tendency is given to make them later formed coils are 1003 01:02:42.960 --> 01:02:46.400 opposite to those, whether turned to the right or to 1004 01:02:46.440 --> 01:02:50.199 the left, which are first made. Take a piece of 1005 01:02:50.280 --> 01:02:52.760 string and let it hang down with the lower end 1006 01:02:52.880 --> 01:02:56.559 fixed to the floor. Then wind the upper end, holding 1007 01:02:56.679 --> 01:03:01.480 the string quite loosely, spirally round a purpose pencil, and 1008 01:03:01.519 --> 01:03:04.480 this will twist the lower part of the string. And 1009 01:03:04.639 --> 01:03:08.719 after it has been sufficiently twisted, it will be seen 1010 01:03:08.760 --> 01:03:12.280 to curve itself into an open spire, with the curves 1011 01:03:12.360 --> 01:03:15.840 running in an opposite direction to those round the pencil, 1012 01:03:16.000 --> 01:03:19.119 and consequently with a straight piece of string between the 1013 01:03:19.159 --> 01:03:22.920 opposed spires. In short, we have given to the string 1014 01:03:23.119 --> 01:03:27.480 the regular spiral arrangement of a tendril caught at both ends. 1015 01:03:27.840 --> 01:03:32.119 The spiral contraction generally begins at the extremity which has 1016 01:03:32.199 --> 01:03:36.360 clasped the support, and this first formed spires give a 1017 01:03:36.440 --> 01:03:40.239 twist to the axis of the tendril, which necessarily inclines 1018 01:03:40.280 --> 01:03:44.440 the basal part into an opposite spiral curvature. I cannot 1019 01:03:44.480 --> 01:03:49.440 resist giving one other illustration, though superfluous. When a haberdasher 1020 01:03:49.559 --> 01:03:52.840 winds up ribbon for a customer, he does not wind 1021 01:03:52.840 --> 01:03:56.039 it into a single coil, for if he did, the 1022 01:03:56.119 --> 01:03:59.559 ribbon would twist itself as many times as there were coils. 1023 01:04:00.079 --> 01:04:02.280 But he winds it into a figure of eight on 1024 01:04:02.360 --> 01:04:05.679 his thumb and little finger, so that he alternately takes 1025 01:04:05.760 --> 01:04:09.920 turns in opposite directions, and thus the ribbon is not twisted. 1026 01:04:10.519 --> 01:04:14.239 So it is with tendrils with this sole difference, that 1027 01:04:14.280 --> 01:04:17.760 they take several consecutive turns in one direction, and then 1028 01:04:17.840 --> 01:04:20.760 the same number in an opposite direction, but in both 1029 01:04:20.840 --> 01:04:25.920 cases the self twisting is avoided. Summary on the nature 1030 01:04:25.960 --> 01:04:30.320 and action of tendrils. With the majority of tendril bearing plants, 1031 01:04:30.360 --> 01:04:33.760 the young internodes revolve in more or less broad ellipses 1032 01:04:34.199 --> 01:04:37.880 like those made by twining plants, But the figures described 1033 01:04:37.920 --> 01:04:43.079 when carefully traced generally form irregular ellipsoidal spirals. The rate 1034 01:04:43.119 --> 01:04:46.960 of revolution varies from one to five hours in different species, 1035 01:04:47.159 --> 01:04:50.239 and consequently is in some cases more rapid than with 1036 01:04:50.440 --> 01:04:53.719 any twining plant, and is never so slow as with 1037 01:04:53.960 --> 01:04:57.440 those many twiners which take more than five hours for 1038 01:04:57.519 --> 01:05:01.679 each revolution. The direction is variable even in the same 1039 01:05:01.800 --> 01:05:06.519 individual plant. In Passiflora, the internodes of only one

species 1040 01:05:06.599 --> 01:05:09.920 have the power of revolving. The vine is the weakest 1041 01:05:09.960 --> 01:05:13.920 revolver observed on me, apparently exhibiting only a trace of 1042 01:05:13.960 --> 01:05:18.519 its former power. In the acrimocarpus, the movement is interrupted 1043 01:05:18.519 --> 01:05:22.719 by many long pauses. Very few tendril bearing plants can 1044 01:05:22.800 --> 01:05:26.639 spirally twine up any upright stick, although the power of 1045 01:05:26.679 --> 01:05:30.119 twining has generally been lost, either from the stiffness or 1046 01:05:30.199 --> 01:05:33.280 shortness of the internodes, from the size of the leaves, 1047 01:05:33.519 --> 01:05:36.920 or from some other unknown cause. The revolving movement of 1048 01:05:36.920 --> 01:05:40.079 the stem serves to bring the tendrils into contact with 1049 01:05:40.199 --> 01:05:46.719 surrounding objects. The tendrils themselves also spontaneously revolve. The movement 1050 01:05:46.800 --> 01:05:49.559 begins whilst if the tendril is young and is at 1051 01:05:49.599 --> 01:05:54.360 first slow. The mature tendrils of Bignonia literalis move much 1052 01:05:54.400 --> 01:05:58.599 slower than the internodes. Generally, the internodes and tendrils revolve 1053 01:05:58.679 --> 01:06:02.599 together at the same ring. In Scissus and Kobea, and 1054 01:06:02.760 --> 01:06:06.880 most Passiflora, the tendrils alone revolve. In other cases, as 1055 01:06:06.920 --> 01:06:11.320 with Latharus afaca, only the internodes move, carrying with them 1056 01:06:11.360 --> 01:06:14.960 the motionless tendrils. And lastly, and this is the fourth 1057 01:06:15.039 --> 01:06:19.880 possible case, neither internodes nor tendrils spontaneously revolve, as with 1058 01:06:20.039 --> 01:06:26.599 Latharus grandiflorus and Amphilopsis. In most Bignonias Ecroymocarpus Metusia, and 1059 01:06:26.679 --> 01:06:32.159 the fumarriaca, the internodes, petioles, and tendrils all move harmoniously together. 1060 01:06:32.840 --> 01:06:35.719 In every case, the conditions of life must be favorable 1061 01:06:35.760 --> 01:06:37.960 in order that the different parts should act in a 1062 01:06:37.960 --> 01:06:41.960 perfect manner. The tendrils revolved by the curvature of their 1063 01:06:41.960 --> 01:06:46.239 whole length, accepting the extensitive extremity and the base which 1064 01:06:46.320 --> 01:06:49.960 parts do not move or move but little. The movement 1065 01:06:50.119 --> 01:06:53.039 is of the same nature as that of the revolving internodes, 1066 01:06:53.280 --> 01:06:56.679 and from the observations of sex and age diveies, no 1067 01:06:56.800 --> 01:06:59.760 doubt is due to the same cause, namely, the rapid 1068 01:06:59.800 --> 01:07:03.119 grous growth of a longitudinal band which travels round the 1069 01:07:03.199 --> 01:07:08.320 tendril and successfully bows each part to the opposite side. Hence, 1070 01:07:08.400 --> 01:07:11.880 if a line is painted along

that surface, which happens 1071 01:07:11.920 --> 01:07:15.199 at the time to be convex, the line becomes first lateral, 1072 01:07:15.239 --> 01:07:20.159 then concave, then lateral, and ultimately again convex. This experiment 1073 01:07:20.199 --> 01:07:22.920 can be tried only on the thicker tendrils, which are 1074 01:07:22.960 --> 01:07:26.440 not affected by a thin crust of dried paint. The 1075 01:07:26.519 --> 01:07:30.360 extremities are often slightly curved or hooked, and the curvature 1076 01:07:30.360 --> 01:07:33.480 of this part is never reversed. In this respect, they 1077 01:07:33.480 --> 01:07:36.920 differ from the extremities of twining choots, which not only 1078 01:07:36.960 --> 01:07:40.519 reverse their curvature or at least become periodically straight, but 1079 01:07:40.639 --> 01:07:43.440 curve themselves in a greater degree than the lower part. 1080 01:07:44.559 --> 01:07:48.079 In most other respects, a tendril acts as if it 1081 01:07:48.079 --> 01:07:51.920 were one of several revolving internodes, which all move together 1082 01:07:52.000 --> 01:07:56.559 by successfully bending to each point of the compass. There is, however, 1083 01:07:56.679 --> 01:08:00.960 in many cases, this unimportant difference that the curving tendril 1084 01:08:01.039 --> 01:08:04.119 is separated from the curving internode by a rigid petiole. 1085 01:08:04.800 --> 01:08:07.880 With most tendril bearers, the summit of stem or shoot 1086 01:08:07.960 --> 01:08:11.480 projects above the point from which the tendril arises, and 1087 01:08:11.639 --> 01:08:14.599 it is generally bent to one side so as to 1088 01:08:14.639 --> 01:08:17.319 be out of the way of the revolutions swept by 1089 01:08:17.359 --> 01:08:20.960 the tendril. In those plants in which the terminal shoot 1090 01:08:21.039 --> 01:08:23.279 is not sufficiently out of the way, as we have 1091 01:08:23.399 --> 01:08:27.079 seen with the ichinocystus, as soon as the tendril comes 1092 01:08:27.119 --> 01:08:30.319 in its revolving course to this point, it stiffens and 1093 01:08:30.399 --> 01:08:34.159 straightens itself, and thus rising vertically up passes over the 1094 01:08:34.239 --> 01:08:39.079 obstacle in an aberrable manner. All tendrils are sensitive, but 1095 01:08:39.399 --> 01:08:42.960 in various degrees to contact with an object and curve 1096 01:08:43.159 --> 01:08:47.159 towards the touched side. With several plants, a single touch 1097 01:08:47.279 --> 01:08:50.600 so slight as only just to move the highly flexible 1098 01:08:50.680 --> 01:08:56.600 tendril is enough to induce curvature passiflorogressless possesses the most 1099 01:08:56.640 --> 01:09:00.000 sensitive tendrils, which I have observed, A bit of platis 1100 01:09:00.159 --> 01:09:03.399 no wire zero point zero two of a grain one 1101 01:09:03.439 --> 01:09:06.760 point two three milligrams in weight gently placed on the 1102 01:09:06.800 --> 01:09:10.680 concave point caused a tendril to become hooked, as did 1103 01:09:10.720 --> 01:09:14.880 a loop of soft, thin cotton thread weighing one thirty 1104 01:09:14.920 --> 01:09:19.000 second of a grain two point zero two milligrams, with 1105 01:09:19.079 --> 01:09:22.600 the tendrils of several other plants loops weighing one sixteenth 1106 01:09:22.600 --> 01:09:26.600 of a grain four point zero five milligrams sufficed. The 1107 01:09:26.640 --> 01:09:30.000 point of a tendril of Passiflora Grecillus began to move 1108 01:09:30.079 --> 01:09:32.880 distinctly into twenty five seconds after a touch, and in 1109 01:09:32.960 --> 01:09:37.359 many cases after thirty seconds. A segrae also saw movement 1110 01:09:37.439 --> 01:09:42.920 in the tendrils of gugubidaesius genus sissios in thirty seconds. 1111 01:09:43.640 --> 01:09:46.479 The tendrils of some other plants, when lightly rubbed, move 1112 01:09:46.600 --> 01:09:50.039 in a few minutes, Dicentra in half an hour, with 1113 01:09:50.159 --> 01:09:53.479 Smeolacs in an hour and a quarter or half, and 1114 01:09:53.560 --> 01:09:58.439 with Ampilopsis still more slowly. The curing movement consequent on 1115 01:09:58.479 --> 01:10:02.159 a single touch continues to increase for a considerable time, 1116 01:10:02.439 --> 01:10:06.479 then ceases. After a few hours. The tendril uncurls itself 1117 01:10:06.520 --> 01:10:09.920 and is again ready to act. The tendrils of several 1118 01:10:10.039 --> 01:10:12.960 kinds of plant were caused to bend by extremely light 1119 01:10:13.039 --> 01:10:16.600 weights suspended on them. They seemed to grow accustomed to 1120 01:10:16.640 --> 01:10:20.319 so slight a stimulus and straightened themselves as if the 1121 01:10:20.359 --> 01:10:23.880 loops had been removed. It makes no difference what sort 1122 01:10:23.920 --> 01:10:27.399 of object to tendril touches, with the remarkable exception of 1123 01:10:27.479 --> 01:10:30.680 other tendrils and drops of water, as was observed with 1124 01:10:30.760 --> 01:10:36.880 the extremely sensitive tendrils of passifloragresculus and of the Chinocystus. 1125 01:10:37.279 --> 01:10:40.600 I have however, seen tendrils of the bryony which had 1126 01:10:40.840 --> 01:10:44.479 temporarily caught other tendrils, and often, in the case of 1127 01:10:44.520 --> 01:10:48.720 the vine, tendrils of which the extremities are permanently and 1128 01:10:48.760 --> 01:10:53.640 slightly curved, are sensitive only on the concave surface. Other tendrils, 1129 01:10:53.720 --> 01:10:57.600 such as those of the kobee, although furnished with horny 1130 01:10:57.640 --> 01:11:01.359 hooks directed to one side, and those of Siss's discolor, 1131 01:11:01.840 --> 01:11:05.840 are sensitive on all sides. Hence, the tendrils of this 1132 01:11:06.000 --> 01:11:09.479 latter plant, when stimulated by a touch of equal force 1133 01:11:09.520 --> 01:11:13.279 on opposite sides, did not bend. The inferior and lateral 1134 01:11:13.319 --> 01:11:17.479 surfaces of the

tendrils of Motiicia are sensitive, but not 1135 01:11:17.560 --> 01:11:22.319 the upper surface. With branched tendrils, the several branches act alike, 1136 01:11:22.680 --> 01:11:25.960 but in Hamburia the lateral spur like branch does not 1137 01:11:26.039 --> 01:11:31.119 acquire for excellent reasons which have been explained. Its sensitiveness 1138 01:11:31.119 --> 01:11:35.000 nearly so soon as the main branch. With most tendrils, 1139 01:11:35.039 --> 01:11:37.399 the lower or basal part is either not at all 1140 01:11:37.479 --> 01:11:41.680 sensitive or sensitive only to blogged contact. We thus see 1141 01:11:41.760 --> 01:11:46.319 that the sensitiveness of tendrils is a special eye localized capacity. 1142 01:11:47.039 --> 01:11:50.720 It is quite independent of the power of spontaneously revolving, 1143 01:11:51.319 --> 01:11:54.119 for the curling of the terminal portion from touch does 1144 01:11:54.159 --> 01:11:58.680 not the least interrupt the former movement. In Bignonia on 1145 01:11:58.840 --> 01:12:02.359 Gris and its allies, the petioles of the leaves as 1146 01:12:02.399 --> 01:12:06.720 well as the tendrils, are sensitive to a touch. Twining plants, 1147 01:12:06.720 --> 01:12:09.199 when they come into contact with a stick, curl round 1148 01:12:09.239 --> 01:12:12.640 it invariably in the direction of their revolving movement, but 1149 01:12:12.680 --> 01:12:16.680 the tendrils curl indifferently to either side, in accordance with 1150 01:12:16.720 --> 01:12:19.039 the position of the stick and the side which is 1151 01:12:19.079 --> 01:12:23.119 first touched. The clasping movement of the extremity is apparently 1152 01:12:23.199 --> 01:12:27.439 not steady, but undulatory or vermicular in its nature, as 1153 01:12:27.479 --> 01:12:29.680 may be inferred from the curious manner in which the 1154 01:12:29.720 --> 01:12:35.399 tendrils of ichinocistis slowly crawled round a smooth stick. As 1155 01:12:35.439 --> 01:12:39.640 with a few exceptions, tendrils spontaneously revolve. It may be 1156 01:12:39.720 --> 01:12:43.960 asked why have they been endowed with sensitiveness, Why when 1157 01:12:44.119 --> 01:12:46.279 they come into contact with the stick do they not 1158 01:12:46.520 --> 01:12:51.199 like twining plants spirally lined round it. One reason may 1159 01:12:51.239 --> 01:12:53.800 be that they are, in most cases so flexible and 1160 01:12:53.920 --> 01:12:57.039 thin that when brought into contact with any object, they 1161 01:12:57.079 --> 01:13:00.319 would almost certainly yield and be dragged onwards by the 1162 01:13:00.359 --> 01:13:05.680 revolving movement. However, the sensitive extremities have no revolving power 1163 01:13:05.800 --> 01:13:08.319 as far as I have observed, and could not, by 1164 01:13:08.359 --> 01:13:12.039 this means curl round to support. With twining plants, on 1165 01:13:12.079 --> 01:13:15.840 the other hand, the extremity spontaneously bends more than any 1166 01:13:15.840 --> 01:13:19.479 other part, and this is of high importance for the 1167 01:13:19.520 --> 01:13:22.159 ascent of the plant, as may be seen on a 1168 01:13:22.199 --> 01:13:25.560 windy day. It is, however, possible that the slow movement 1169 01:13:25.640 --> 01:13:28.800 of the basal and stiffer parts of certain tendrils which 1170 01:13:28.840 --> 01:13:32.319 wind around sticks placed in their path, may be analogous 1171 01:13:32.319 --> 01:13:36.279 to that of twining plants. But I hardly attended sufficiently 1172 01:13:36.359 --> 01:13:38.680 to this point, and it would have been difficult to 1173 01:13:38.720 --> 01:13:43.119 distinguish between a movement due to extremely dull irritability from 1174 01:13:43.159 --> 01:13:46.199 the arrestment of the lower part whilst the upper part 1175 01:13:46.279 --> 01:13:50.560 continued to move onwards. Tendrils which are only three forts 1176 01:13:50.640 --> 01:13:54.079 grown and perhaps even at an earlier age, but not 1177 01:13:54.159 --> 01:13:57.239 whilst extremely young, have the power of revolving and of 1178 01:13:57.239 --> 01:14:01.880 grasping any object which they touch. These two capacities are 1179 01:14:01.960 --> 01:14:05.520 generally acquired at about the same period, and both fail 1180 01:14:05.600 --> 01:14:09.399 when the tendril is full grown. But in Kobella and 1181 01:14:09.560 --> 01:14:13.520 Pasiflora punctata, the tendrils begin to revolve in a useless 1182 01:14:13.560 --> 01:14:18.199 manner before they have become sensitive. In Echinocystus, they retain 1183 01:14:18.279 --> 01:14:22.039 their sensitiveness for some time after they have ceased to revolve, 1184 01:14:22.359 --> 01:14:25.600 and after they have sunk downwards. In this position, Even 1185 01:14:25.640 --> 01:14:28.600 if they were able to seize an object, such power 1186 01:14:28.680 --> 01:14:32.039 would be of no service in supporting the stem. It 1187 01:14:32.119 --> 01:14:36.079 is a rare circumstance, thus, to detect any superfluity or 1188 01:14:36.119 --> 01:14:40.279 imperfection in the action of tendrils organs which are so 1189 01:14:40.399 --> 01:14:43.520 excellently adapted for the functions which they have to perform. 1190 01:14:44.159 --> 01:14:46.279 But we see that they are not always perfect, and 1191 01:14:46.359 --> 01:14:49.520 it would be rash to assume that any existing tendril 1192 01:14:49.720 --> 01:14:54.520 has reached the utmost limit of perfection. Some tendrils have 1193 01:14:54.640 --> 01:14:58.920 their resvolving motion accelerated or retarded in moving to or 1194 01:14:58.960 --> 01:15:02.680 from the light. Others, as with the peace, seem indifferent 1195 01:15:02.760 --> 01:15:06.560 to its action. Others move steadily from the light to 1196 01:15:06.600 --> 01:15:09.399 the dark, and this aids them in an important manner 1197 01:15:09.479 --> 01:15:13.279 in finding a support. For instance, the tendrils of Bignonia 1198 01:15:13.319 --> 01:15:16.800

capriolata then from the light to the dark as truly 1199 01:15:16.880 --> 01:15:20.720 as a wind vane from the wind. In the ecromoral carpass. 1200 01:15:21.000 --> 01:15:23.960 The extremities alone twist and turn about so as to 1201 01:15:23.960 --> 01:15:27.119 bring their finer branches and hooks into close contact with 1202 01:15:27.199 --> 01:15:31.479 any dark surface or into crevices and holes. A short 1203 01:15:31.479 --> 01:15:34.840 time after tendril has caught a support, it contracts, with 1204 01:15:34.960 --> 01:15:38.000 some rare exceptions, into a spire. But the manner of 1205 01:15:38.079 --> 01:15:42.479 contraction and its several important advantages thus gained, have been 1206 01:15:42.600 --> 01:15:46.600 discussed so lately that nothing need here be repeated on 1207 01:15:46.680 --> 01:15:50.800 the subject. Tendrils, soon after catching a support grow much 1208 01:15:51.079 --> 01:15:55.359 stronger and thicker, and sometimes more durable, to a wonderful degree, 1209 01:15:55.560 --> 01:16:00.000 and this shows how much their internal tissues must be changed. Occasionally, 1210 01:16:00.079 --> 01:16:02.279 it is the part which is wound round a support 1211 01:16:02.359 --> 01:16:06.319 which chiefly becomes thicker and stronger. I have seen, for instance, 1212 01:16:06.399 --> 01:16:10.760 this part of a tendril of Bignonia aquinoctialis twice as 1213 01:16:10.840 --> 01:16:13.600 thick and rigid as the free basal tendrils, which have 1214 01:16:13.680 --> 01:16:17.000 caught nothing soon shrink and wether. But in some species 1215 01:16:17.000 --> 01:16:20.800 of Bignonia they disarticulate and fall off like leaves in autumn. 1216 01:16:21.720 --> 01:16:25.159 Anyone who had not closely observed tendrils of many kinds 1217 01:16:25.239 --> 01:16:28.680 would probably infer that their action was uniform. This is 1218 01:16:28.720 --> 01:16:31.640 the case with the simpler kinds, which simply curl round 1219 01:16:31.720 --> 01:16:35.399 an object of moderate thickness, whatever its nature may be. 1220 01:16:35.960 --> 01:16:38.720 But the genus Bignonia shows us what diversity of the 1221 01:16:38.760 --> 01:16:42.199 action there may be between the tendrils of closely allied species. 1222 01:16:42.920 --> 01:16:45.520 In all the nine species observed by me, the young 1223 01:16:45.640 --> 01:16:49.680 internals revolve vigorously, the tendrils alter revolve, but in some 1224 01:16:49.840 --> 01:16:52.840 of the species in a very feeble manner. And lastly, 1225 01:16:52.880 --> 01:16:56.319 the petioles of nearly all revolve, though with unequal power. 1226 01:16:57.119 --> 01:17:00.079 The petioles of three of the species, and the tendrils 1227 01:17:00.079 --> 01:17:04.079 of all, are sensitive to contact. In the first described species, 1228 01:17:04.079 --> 01:17:06.720 the tendrils resemble in shape of bird's foot and are 1229 01:17:06.760 --> 01:17:09.640 of no service to the stem, inspirally ascending a thin 1230 01:17:09.880 --> 01:17:12.880 upright stick, but they can seize firm hold of a 1231 01:17:12.880 --> 01:17:16.640 twig or branch. When the stem twinds round a somewhat 1232 01:17:16.680 --> 01:17:19.960 thick stick, a slight degree of sensitiveness possessed by the 1233 01:17:20.000 --> 01:17:23.159 petioles is brought into play, and the whole leaf, together 1234 01:17:23.239 --> 01:17:26.960 with the tendrils, winds round it. In Bia Aunguis, the 1235 01:17:27.000 --> 01:17:30.000 petioles are more sensitive and have greater power of movement 1236 01:17:30.079 --> 01:17:33.159 than those of the last species. They are able, together 1237 01:17:33.239 --> 01:17:36.920 with the tendrils, to wind inextricably round a thin upright stick, 1238 01:17:37.399 --> 01:17:41.520 but the stem does not twine so well. BA. Tridiana 1239 01:17:41.560 --> 01:17:44.880 has similar powers, but in addition, amids aerial roots which 1240 01:17:44.920 --> 01:17:48.520 adhere to the wood. In BI Venusta, the tendrils are 1241 01:17:48.520 --> 01:17:53.520 converted into elongated, three pronged grapnels, which move spontaneously in 1242 01:17:53.600 --> 01:17:58.800 conspicuous manner. The petioles, however, have lost their sensitiveness. The 1243 01:17:58.840 --> 01:18:02.920 stem of this specie can twine round an upright stick, 1244 01:18:03.000 --> 01:18:05.840 and is aided in its ascent by the tendrils seizing 1245 01:18:05.840 --> 01:18:09.920 the stick alternately some way above and then contracting spirally. 1246 01:18:10.680 --> 01:18:15.920 In B. Litteralis, the tendrils, petules, and internodes all revolve spontaneously. 1247 01:18:16.520 --> 01:18:19.960 The stem however, cannot twine, but ascends an upright stick 1248 01:18:20.039 --> 01:18:23.239 by seizing it above with both tendrils together, which then 1249 01:18:23.279 --> 01:18:26.720 contract into a spire. The tips of these tendrils become 1250 01:18:26.760 --> 01:18:31.640 developed into adhesive discs. B. Speciosa possesses similar powers of 1251 01:18:31.720 --> 01:18:34.840 movement as the last species, but it cannot twine round 1252 01:18:34.840 --> 01:18:37.560 a stick, though it can ascend by clasping the stick 1253 01:18:37.600 --> 01:18:41.800 horizontally with one or both of its unbranched tendrils. These 1254 01:18:41.840 --> 01:18:46.479 tendrils continually insert their pointed ends into minute crevices or holes, 1255 01:18:46.680 --> 01:18:50.159 but as they are always withdrawn by the subsequent spiral contraction, 1256 01:18:50.600 --> 01:18:54.920 the habit seems to us in our ignorance useless. Lastly, 1257 01:18:54.960 --> 01:18:59.199 the stem of B. Caprilata twines imperfectly. The much branched 1258 01:18:59.239 --> 01:19:02.399 tendrils revolve in a capricious manner and bend from the 1259 01:19:02.479 --> 01:19:05.560 light to their dark their hooked extremities even whilst the 1260 01:19:05.560 --> 01:19:09.279 immature crawl into crevices, and when mature sees any thin

1261 01:19:09.399 --> 01:19:13.520 projecting point in either case, they develop adhesive disks, and 1262 01:19:13.600 --> 01:19:17.279 these have the power of enveloping. The finest fibers In 1263 01:19:17.359 --> 01:19:21.439 the allied A cremocarpus, the internals, petiles and much branched 1264 01:19:21.439 --> 01:19:26.479 tendrils all spontaneously revolve together. The tendrils do not as 1265 01:19:26.560 --> 01:19:29.439 a whole turned from the light, but their bluntly hooked 1266 01:19:29.439 --> 01:19:32.960 extremities arrange themselves neatly on any surface with which they 1267 01:19:32.960 --> 01:19:36.479 come into contact, apparently so as to avoid the light. 1268 01:19:37.399 --> 01:19:41.000 They act best when each branch seizes a few thin stems, 1269 01:19:41.039 --> 01:19:43.800 like the columbs of a glass, which they afterwards draw 1270 01:19:43.880 --> 01:19:47.000 together into a solid bundle by the spiral contraction of 1271 01:19:47.039 --> 01:19:52.319 all the branches. In Kobei, the highly finely branched tendrils 1272 01:19:52.359 --> 01:19:57.159 alone revolve. The branches terminate in sharp, hard, double little hooks, 1273 01:19:57.439 --> 01:20:00.640 with both points directed to the same side, and these 1274 01:20:00.720 --> 01:20:03.920 turned by well adapted movements to any object with which 1275 01:20:03.920 --> 01:20:07.760 they come into contact. The tips of the branches also 1276 01:20:07.800 --> 01:20:11.680 crawl into dark crevices or holes. The tendrils and internodes 1277 01:20:11.720 --> 01:20:15.680 of Ampelopsis have little or no power revolving. The tendrils 1278 01:20:15.720 --> 01:20:19.560 are but little sensitive to contacts. Their hooked extremities cannot 1279 01:20:19.680 --> 01:20:23.079 seize thin objects. They will not even clasp a stick 1280 01:20:23.239 --> 01:20:26.520 unless in extreme need of support. But they turn from 1281 01:20:26.560 --> 01:20:29.119 the light to the dark, and spreading out their branches 1282 01:20:29.159 --> 01:20:33.079 in contact with nearly any flat surface developed discs. These 1283 01:20:33.119 --> 01:20:35.680 adhere by the secretion of some cement to a wall 1284 01:20:36.039 --> 01:20:38.960 or even to a polished surface, and this is more 1285 01:20:39.000 --> 01:20:43.359 than the disks of the Bignonia caprilata can affect. The 1286 01:20:43.439 --> 01:20:46.479 rapid development of these adherent discs is one of the 1287 01:20:46.479 --> 01:20:51.199 most remarkable peculiarities possessed by any tendrils. We have seen 1288 01:20:51.239 --> 01:20:54.520 that such discs are formed by two species of Bignonia, 1289 01:20:54.680 --> 01:20:59.840 by Ampelopsis and according to Nauden, by the coucurbetaceous genus 1290 01:21:00.079 --> 01:21:04.560 to Ponopsis ad herons. In anguera, the lower surface of 1291 01:21:04.600 --> 01:21:07.399 the tendril, after it has wound round a stick, forms 1292 01:21:07.399 --> 01:21:11.159 a coarsely cellular layer which closely fits the wood but 1293 01:21:11.359 --> 01:21:15.960 is not adherent, whilst in Hamburia a similar layer is adherent. 1294 01:21:16.680 --> 01:21:20.439 The growth of these cellular outgrowths depends, except in the 1295 01:21:20.479 --> 01:21:24.359 case of the Haplolophium and of one species of Ampilopsis, 1296 01:21:24.840 --> 01:21:28.840 on the stimulus from contact. It is a singular fact 1297 01:21:28.920 --> 01:21:32.800 that three families so widely distinct as the big Noniacia, 1298 01:21:33.119 --> 01:21:38.600 Thetasa and Cripidacia, should possess species with tendrils having this 1299 01:21:38.760 --> 01:21:43.359 remarkable power. Sax attributes all the movements of tendrils to 1300 01:21:43.479 --> 01:21:47.079 rapid growth on the side opposite to that which becomes concave. 1301 01:21:47.720 --> 01:21:52.000 These movements consist of revolving nutation, the bending to and 1302 01:21:52.039 --> 01:21:55.600 from the light, and in opposition to gravity, those caused 1303 01:21:55.600 --> 01:21:59.359 by a touch and spiral contraction. It is rash to 1304 01:21:59.399 --> 01:22:02.159 differ from so great an authority, but I cannot believe 1305 01:22:02.239 --> 01:22:05.439 that one at least of these movements curvature from a 1306 01:22:05.520 --> 01:22:08.800 touch is thus caused. In the first place. It may 1307 01:22:08.840 --> 01:22:12.279 be remarked that the movement of a mutation differs from 1308 01:22:12.439 --> 01:22:15.399 that due to touch in so far that in some 1309 01:22:15.479 --> 01:22:18.359 cases the two powers are acquired by the same tendril 1310 01:22:18.640 --> 01:22:21.760 at different periods of growth, and the sensitive part of 1311 01:22:21.760 --> 01:22:25.399 the tendril does not seem capable of mutation. One of 1312 01:22:25.439 --> 01:22:28.479 my chief reasons for doubting whether the curvature from a 1313 01:22:28.520 --> 01:22:31.840 touch is the result of growth is the extraordinary rapidity 1314 01:22:31.920 --> 01:22:34.920 of the movement. I have seen the extremity of a 1315 01:22:34.960 --> 01:22:39.279 tendril of Passiflora grisillus after being touched distinctly bent in 1316 01:22:39.359 --> 01:22:43.079 twenty five seconds, and often in thirty seconds. So it 1317 01:22:43.159 --> 01:22:47.279 is with the thicker tendril of sissios. It appears hardly 1318 01:22:47.359 --> 01:22:51.239 credible that their outer surfaces could have actually grown in length, 1319 01:22:51.520 --> 01:22:55.520 which implies a permanent modification of structure in so short 1320 01:22:55.600 --> 01:23:00.239 a time. The growth. Moreover, on this view must be considerable, 1321 01:23:00.640 --> 01:23:03.279 for if the touch has been at all rough, the 1322 01:23:03.359 --> 01:23:06.399 extremity is coiled in two or three minutes into a 1323 01:23:06.439 --> 01:23:10.119 spire of several turns. When the extreme tip of the 1324 01:23:10.159 --> 01:23:14.359 tendril of echinocystis caught holes of a smooth

stick, it 1325 01:23:14.479 --> 01:23:18.079 coiled itself in a few hours, as described at page 1326 01:23:18.159 --> 01:23:22.479 one thirty two, twice or thrice around the stick, apparently 1327 01:23:22.520 --> 01:23:26.880 by an undulatory movement. At first I attributed this movement 1328 01:23:26.880 --> 01:23:30.439 to the growth of the outside black marks were therefore made, 1329 01:23:30.479 --> 01:23:33.520 and the interspace is measured, but I could not thus 1330 01:23:33.560 --> 01:23:37.640 detect any increase in length. Hence, it seems probable in 1331 01:23:37.680 --> 01:23:40.000 this case and in others, that the curvature of the 1332 01:23:40.039 --> 01:23:42.680 tendril from a touch depends on the contraction of the 1333 01:23:42.720 --> 01:23:48.079 cells along the concave side. Sax himself admits that if 1334 01:23:48.119 --> 01:23:50.960 the growth which takes place in the entire tendril at 1335 01:23:51.000 --> 01:23:53.760 the time of contact with the support is small, a 1336 01:23:53.840 --> 01:23:58.279 considerable acceleration occurs on the convex surface, but in general 1337 01:23:58.359 --> 01:24:01.800 there is no elongation on the concave surface, or there 1338 01:24:01.800 --> 01:24:04.680 may even be a contraction. In the case of a 1339 01:24:04.760 --> 01:24:09.279 tendril of cucurbita, this contraction amounted to nearly one third 1340 01:24:09.359 --> 01:24:13.479 of the original length. In a subsequent passage, Sax seems 1341 01:24:13.479 --> 01:24:16.920 to feel some difficulty in accounting for this kind of contraction. 1342 01:24:17.720 --> 01:24:20.920 It must, not, however, be supposed from the foregoing remarks, 1343 01:24:20.920 --> 01:24:26.279 that I entertain any doubt after reading DeVries observations about 1344 01:24:26.319 --> 01:24:31.279 the outer and stretched surfaces of attached tendrils afterwards increasing 1345 01:24:31.319 --> 01:24:34.800 in length by growth. Such increase seems to make quite 1346 01:24:34.840 --> 01:24:38.880 compatible with the first movement being independent of growth. Why 1347 01:24:38.920 --> 01:24:41.520 a delicate touch should cause one side of a tendril 1348 01:24:41.560 --> 01:24:44.760 to contract we know as little as why, on the 1349 01:24:44.840 --> 01:24:48.359 view held by Sachs, it should be to extraordinarily rapid 1350 01:24:48.399 --> 01:24:51.880 growth of the opposite side. The chiefer sole reason for 1351 01:24:51.920 --> 01:24:54.359 the belief that the curvature of the tendril when touched 1352 01:24:54.680 --> 01:24:57.159 is due to rapid growth seems to be that the 1353 01:24:57.199 --> 01:25:00.800 tendrils lose their sensitiveness and power of movement after we 1354 01:25:00.880 --> 01:25:03.680 have grown to their full length. But this fact is 1355 01:25:03.760 --> 01:25:07.279 intelligible if we bear in mind that all the functions 1356 01:25:07.319 --> 01:25:10.359 of a tendril are adapted to drag up the terminal 1357 01:25:10.399 --> 01:25:14.199 growing shoot towards the light. Of what use would it 1358 01:25:14.199 --> 01:25:17.279 be if an old and full grown tendril arising from 1359 01:25:17.319 --> 01:25:19.800 the lower part of a chute were to retain its 1360 01:25:19.880 --> 01:25:23.680 power of clasping support. This would be of no use. 1361 01:25:23.920 --> 01:25:27.359 And we have seen with tendrils so many instances of 1362 01:25:27.399 --> 01:25:30.960 close adaptation and of the economy of means, that we 1363 01:25:31.039 --> 01:25:34.239 may feel assured that they would acquire irritability and the 1364 01:25:34.239 --> 01:25:38.159 power of clasping at the proper age, namely youth, and 1365 01:25:38.159 --> 01:25:42.159 would not uselessly retain such power beyond the proper age. 1366 01:25:43.000 --> 01:25:44.279 End of Chapter four