C 8H 3 
XVI. On the Motions of the Tendrils of Plants. By Thomas 
Andrew Knight, Esq. F. R. S. In a Letter to the Right Hon. 
Sir Joseph Banks, Bart. K. B. P. R. S. 
Read May 4, 1812. 
My Dear Sir, 
The motions of the tendrils of plants, and the efforts they 
apparently make to approach and attach themselves to conti- 
guous objects, have been supposed by many naturalists to 
originate in some degrees of sensation and perception: and 
though other naturalists have rejected this hypothesis, few, or 
no experiments have been made by them to ascertain with 
what propriety the various motions of tendrils, of different 
kinds, can be attributed to peculiarity of organization, and the 
operation of external causes. I was consequently induced, 
during the last summer, to employ a considerable portion of 
time to watch the motions of the tendrils of different species 
of plants ; and I have now the pleasure to address to you an 
account of the observations I was enabled to make. 
The plants selected were the Virginia creeper ( the ampe- 
lopsis quinquefolia of Michaux,) the ivy, and the common 
vine and pea. 
A plant of the ampelopsis, which grew in a garden pot, was 
removed to a forcing house in the end of May, and a single 
shoot from it was made to grow perpendicularly upwards, by 
being supported in that position by a very slender bar of wood, 
to which it was bound. The plant was placed in the middle 
