Cuar. IV. ; SUMMARY. 179 
These adhere by the secretion of some cement to a 
wall, or even to a polished surface; and this is more 
than the dises of the Bignonia capreolata can effect. 
The rapid development of these adherent discs is 
one of the most remarkable peculiarities possessed by 
any tendrils. We have seen that such discs are formed 
by two species of Bignonia, by Ampelopsis, and, 
according to Naudin,* by the Cucurbitaceous genus 
Peponopsis adherens. In Anguria the lower surface of 
the tendril, after it has wound round a stick, forms 
a coarsely cellular layer, which closely fits the wood, 
but is not adherent; whilst in Hanburya a similar 
layer is adherent. The growth of these cellular out- 
growths depends, (except in the case of the Haplolophium 
and of one species of Ampelopsis,) on the stimulus from 
contact. It is a singular fact that three families, so 
widely distinct as the Bignoniacee, Vitacee, and 
Cucurbitaceze, should possess species with tendrils 
having this remarkable power. 
Sachs attributes all the movements of tendrils to 
rapid growth on the side opposite to that which 
becomes concave. These movements consist of re- 
volving nutation, the bending to and from the light, 
and in opposition to gravity, those caused by a touch, 
and spiral contraction. Itis rash to differ from so great 
an authority, but I cannot believe that one at least of 
* Annales des Sc, Nat, Bot. 4th series, tum. xii. p, 89, 
