156 TENDRIL-BEARERS. Cuap. IV. 
After a tendril has once firmly coiled itself round 
a stick, it is difficult to imagine of what use the ad- 
hesive cellular layer can be. Owing to the spiral 
contraction which soon ensues, the tendrils were never 
able to remain, excepting in one instance, in contact 
with a thick post or a nearly flat surface ; if they had 
quickly become attached by means of the adhesive 
layer, this would evidently have been of service to the 
plant. : 
The tendrils of Bryonia dioica, Cucurbita ovifera, 
and Cucumis sativa are sensitive and revolve. Whether 
the internodes likewise revolve I did not observe. In 
Anguria Warscewiez, the internodes, though thick 
and stiff, revolve: in this plant the lower surface of 
the tendril, some time after clasping a stick, produces 
a coarsely cellular layer or cushion, which adapts itself 
closely to the wood, like that formed by the tendril of 
the Hanburya ; but it is not in the least adhesive. In 
Zanonia Indica, which belongs to a different tribe of 
the family, the forked tendrils and the internodes re- 
volve in periods between 2 hrs. 8 m. and 3 hrs. 35 m., 
moving against the sun. 
Virace&.—In this family and in the two following, 
namely, the Sapindacez and Passifloracee, the tendrils 
are modified flower-peduncles; and are therefore axial 
in their nature. In this respect they differ from all 
those previously described, with the exception, per- 
haps, of the Cucurbitacez. The homological nature, 
however, of a tendril seems to make no difference 
in its action. 
