166 ON THE MOTIONS OF THE TEN OKI LS OF PLANTS. 



plant evaded the light, just as the tendrils of the ampelopsis had done ; 

 and that they sprang only from such parts of the stems as were fully, or 

 partially, shaded. 



A seedling plant of the peach tree, and one of the ampelopsis and ivy 

 were placed nearly in the centre of the house, and under similar circum- 

 stances ; except that supports, formed of very slender bars of wood, 

 about four inches high, were applied to the ampelopsis and ivy. The 

 peach tree continued to grow nearly perpendicularly, with a slight 

 inclination towards the front and south side of the house, whilst the stems 

 of the ampelopsis and ivy, as soon as they exceeded the height of their 

 supports, inclined many points from the perpendicular line, in the 

 opposite direction. 



It appears therefore that not only the tendrils and claws of these 

 creeping dependent plants, but that their stems also, are made to recede 

 from light, and to press against the opake bodies, which nature intended 

 to support and protect them. 



M. De Candolle, I believe, first observed that the succulent shoots of 

 trees and herbaceous plants, which do not depend upon others for 

 support, are bent towards the point from which they receive light, by the 

 contraction of the cellular substance of their bark upon that side, and 

 I believe his opinion to be perfectly well founded. The operation of light 

 upon the tendrils and stems of the ampelopsis and ivy appears to pro- 

 duce diametrically opposite effects, and to occasion an extension of the 

 cellular bark, wherever that is exposed to its influence ; and this circum- 

 stance affords, I think, a satisfactory explanation why these plants appear 

 to seek and approach contiguous opake objects, just as they would do, if 

 they were conscious of their own feebleness, and of power in the objects, 

 to which they approach, to afford them support and protection. 



The tendril of the vine, as 1 have already stated, is internally similar 

 to that of the ampelopsis, though its external form, and mode of attach- 

 ing itself by twining round any slender body, are very different. Some 

 young plants of this species, which had been raised in pots in the pre- 

 ceding year, and had been headed down to a single bud, were placed in a 

 forcing-house, with the plants I have already mentioned ; and the shoots 

 from these were bound to slender bars of wood, and trained perpen- 

 dicularly upwards. Their tendrils, like those of the ampelopsis, when 

 first emitted, pointed upwards ; but they gradually formed an increasing 

 angle with the stems, and ultimately pointed perpendicularly downwards ; 

 no object having presented itself to which they could attach themselves. 

 Other plants of the vine, under similar circumstances, were trained 



