. The power of movement in plants . Plants; Botany. 130 MODIFIED CIECUMNUTATION. Chap. VIII , wlien the last dot -sras made. Here, then, we haye a distinct heliotropio movement, effected by means of six elongated figures (which if dots had been made every few minutes would have been more or less elliptic) directed towards the light, with the apex of each suc- cessive ellipse nearer to the window than the previous one. Now, if the light had been only a little brighter, the epicotyl would have bowed itself more to the light, as we may safely conclude from the previous trials; there wou
. The power of movement in plants . Plants; Botany. 130 MODIFIED CIECUMNUTATION. Chap. VIII , wlien the last dot -sras made. Here, then, we haye a distinct heliotropio movement, effected by means of six elongated figures (which if dots had been made every few minutes would have been more or less elliptic) directed towards the light, with the apex of each suc- cessive ellipse nearer to the window than the previous one. Now, if the light had been only a little brighter, the epicotyl would have bowed itself more to the light, as we may safely conclude from the previous trials; there would also have been less lateral movement, and the ellipses or otherflgures would have been drawn out into a strongly marked zigzag Une, with probably one or two small loops still formed. If the light had been much brighter, we should have had a slightly zigzag Une, or one quite straight, for there would have been more movement in the direc- tion of the light, and much less from side to side. Sachs states that the older inter- nodes of this TropsBolum are aphe- liotopic; we therefore placed a plant. 111 inches high, in a box, blackened within, but open on one side in front of a north-east window without any blind. A filament was fixed to the third internode from the summit on one plant, and to the fourth internode of another. These internodes were either not old enough, or the light was not suf- ficiently bright, to induce apheUo- tropism, for both plants bent slowly towards, instead of from the window during four days. The course, during two days of the first-mentioned internode, is given in Fig. 176 ; and we see that it either circumnutated on a small scale, or travelled in a zigzag line towards the light. We have thought this case of feeble heliotropism in one of the older internodes of a plant,. Tropceolum majus: heliotropio movement and circumnuta- tion of an old internode to- wards a lateral light, traced on a horizontal glass from 8 Nov. 2nd to 10 20 Nov. 4-th. B
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Keywords: ., bookcentury1800, booksubjectbotany, booksubjectplants, bookyear18
