ON THE MOTIONS OF THE TENDRILS OF PLANTS. 165 



plant was placed in the middle of the house, and was fully exposed to 

 the sun ; and every object around it was removed far beyond the reach 

 of its tendrils. Thus circumstanced, its tendrils, as soon as they were 

 nearly full grown, all pointed towards the north, or back wall, which was 

 distant about eight feet : but not meeting with any thing in that 

 direction, to which they could attach themselves, they declined gradually 

 towards the ground, and ultimately attached themselves to the stems 

 beneath, and the slender bar of wood. 



A. plant of the same species was placed at the east end of the house, 

 near the glass, and was in some measure skreened from the perpendicular 

 light ; when its tendrils pointed towards the west, or centre of the house, 

 as those under the preceding circumstances had pointed towards the 

 north and back wall. This plant was removed to the west end of the 

 house, and exposed to the evening sun, being skreened, as in the pre- 

 ceding case, from the perpendicular light ; and its tendrils, within a few 

 hours, changed their direction, and again pointed to the centre of the 

 house, which was partially covered with vines. This plant was then 

 removed to the centre of the house, and fully exposed to the perpendicular 

 light, and to the sun ; and a piece of dark-coloured paper was placed 

 upon one side of it just within the reach of its tendrils ; and to this 

 substance they soon appeared to be strongly attracted. The paper was 

 then placed upon the opposite side, under similar circumstances, and 

 there it was soon followed by the tendrils. It was then removed, and a 

 piece of plate glass was substituted ; but to this substance the tendrils 

 did not indicate any disposition to approach. The position of the glass 

 was then changed, and care was taken to adjust its surface to the varying 

 position of the sun, so that the light reflected might continue to strike the 

 tendrils ; which then receded from the glass, and appeared to be strongly 

 repulsed by it. 



The tendrils of the ampelopsis very closely resemble those of the vine, 

 in their internal organisation, and in originating from the alburnous 

 substance of the plant; and in being, under certain circumstances, 

 convertible into fruit-stalks. The claws, or claspers of the ivy, to 

 experiments upon which I shall now proceed, appear to be cortical 

 protrusions only ; but to be capable (I have reason to believe) of becoming 

 perfect roots, under favourable circumstances. Experiments, in every 

 respect very nearly similar to the preceding, were made upon this plant ;. 

 but I found it necessary to place the different substances, to which I 

 proposed that the claws should attempt to attach themselves, almost in. 

 contact with the stems of the plants. I observed that the claws of this 



