40 TENDRILS OF PLANTS. 



upon the tendrils and stems of the ampelopsis and ivy, appears 

 to produce diametrically opposite effects, and to occasion an 

 extension of the cellular bark, wherever that is exposed to its 

 influence ; and this circumstance affords, I think, a satisfactory 

 explanation why these plants appear to seek and approach 

 contiguous opaque 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 vine con- The tendril of the vine, as I have already stated, is inter^ 

 explanation*.™ 6 na ^ Mmilar to that of the ampelopsis, though its external 

 form, and mode of attaching itself, by twining round any 

 slender body, are very different. Some young plants of this 

 species, which had been raised in pots in the preceding year, 

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

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

 the shoots from these were bound to slender bars of wood, 

 and trained perpendicularly upwards. Their tendrils, like 

 those of the ampelopsis, when first emitted, pointed upwards j 

 but they gradually formed an increasing angle with the stems, 

 and ultimately pointed perpendicularly downwards 3 no object 

 having presented itself to which they could attach themselves. 

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

 the viae. trained horizontally ; when their tendrils gradually descended 



beneath their stems, with which they ultimately stood very 

 nearly at right angles. 



A third set of plants were trained almost perpendicularly 

 downwards j but with an inclination of a few degrees towards 

 the north j and the tendrils of these permanently retained very 

 nearly their first position, relatively to their stems ; whence 

 it appears, that these organs, like the tendrils of the ampelop- 

 sis, and the claws of the ivy, are to a great extent under the 

 control of light. 

 Thevinedif- A. few other plants of the same species were trained in each 

 fers from the of the preceding methods j but proper objects were placed, in 

 creeper. different situations, near them, with which their tendrils might 



come into contact j and I. was by these means afforded an op- 

 portunity of observing, with accuracy, the difference between 

 the motions of these and those of the ampelopsis, under similar 

 circumstances. The latter almost immediately receded from 

 light, by whatever means that was made to operate upon them j 



and 



