of the Tendrils of Plants. 319 
out a tendril, and as each tendril separates into two divisions 
they do not often fail to come into contact with any object 
within their reach ; and the effects of contact upon the tendril 
are almost immediately visible. It is made to bend towards 
the body it touches, and, if that body be slender, to attach it- 
self firmly by twining round it, in obedience to causes which 
I shall endeavour to point out. 
The tendril of the vine, in its internal organization, is ap- 
parently similar to the young succulent shoot, and leaf-stalk, 
of the same plant ; and it is as abundantly provided with ves- 
sels, or passages, for the sap ; and I have proved that it is 
alike capable of feeding a succulent shoot, or a leaf, when 
grafted upon it. It appears therefore, I conceive, not impro- 
bable, that a considerable quantity of the moving fluid of the 
plant passes through its tendrils ; and that there is a close 
connection between its vascular structure and its motions. 
I have proved in the Philosophical Transactions of 1806, 
that centrifugal force, by operating upon the elongating plu- 
mules of germinating seeds, occasions an increased growth 
and extension upon the external sides of the young stems, and 
that gravitation produces correspondent effects ; probably by 
occasioning the presence of a larger portion of the fluid orga- 
nizable matter of the plant upon the one side, than upon the 
other. The external pressure of any body upon one side of a 
tendril will probably drive this fluid from one side of the ten- 
dril, which will consequently contract, to the opposite side, 
which will expand ; and the tendril will thence be compelled 
to bend round a slender bar of wood or metal, just as the 
stems of germinating seeds are made to bend upwards, and to 
raise the cotyledons out of the ground ; and in support of this 
T t s 
