possesses some degree of voluntary powers,
appears from their necessity to sleep, which we have shewn in Sect. XVIII.
to consist in the temporary abolition of voluntary power. This voluntary
power seems to be exerted in the circular movement of the tendrils of
vines, and other climbing vegetables; or in the efforts to turn the upper
surface of their leaves, or their flowers to the light.

IV. The associations of fibrous motions are observable in the vegetable
world, as well as in the animal. The divisions of the leaves of the
sensitive plant have been accustomed to contract at the same time from the
absence of light; hence if by any other circumstance, as a slight stroke or
injury, one division is irritated into contraction, the neighbouring ones
contract also, from their motions being associated with those of the
irritated part. So the various stamina of the class of syngenesia have been
accustomed to contract together in the evening, and thence if you stimulate
one of them with a pin, according to the experiment of M. Colvolo, they all
contract from their acquired associations.

To evince that the collapsing of the sensitive plant is not owing to any
mechanical vibrations propagated along the whole branch, when a single leaf
is struck with the finger, a leaf of it was slit with sharp scissors, and
some seconds of time passed before the plant seemed sensible of the injury;
and then the whole branch collapsed as far as the principal stem: this
experiment was repeated several times with the least possible impulse to
the plant.

V. 1. For the numerous circumstances in which vegetable buds are analogous
to animals, the reader is referred to the additional notes at the end of
the Botanic Garden, Part I. It is there shewn, that the roots of vegetables
resemble the lacteal system of animals; the sap-vessels in the early
spring, before their leaves expand, are analogous to the placental vessels
of the foetus; that the leaves of land-plants resemble lungs, and those of
aquatic plants the gills of fish; that there are other systems of vessels
resembling the vena portarum of quadrupeds, or the aorta of fish; that the
digestive power of vegetables is similar to that of animals converting the
fluids, which they absorb, into sugar; that their seeds resemble the eggs
of animals, and their buds and bulbs their viviparous offspring. And,
lastly, that the anthers and stigmas are real animals, attached indeed to
their parent tree like