162 TENDRIL-BEARERS. Cuar. IV, 
two days after clasping a stick, and in two more 
days formed séveral spires. It appears, therefore, that 
the contraction does not begin until the tendril is 
grown to nearly its full length. Another young 
tendril of about the same age and length as the last 
did not catch any object; it acquired its full length 
in four days; in six additional days it first became 
flexuous, and in two more days formed one com- 
plete spire. This first spire was formed towards the 
basal end, and the contraction steadily but slowly 
progressed towards the apex; but the whole was not 
closely wound up into a spire until 21 days had 
elapsed from the first observation, that is, until 17 
days after the tendril had grown to its full length. 
The spiral contraction of tendrils is quite indepen- 
dent of their power of spontaneously revolving, for it 
occurs in tendrils, such as those of Lathyrus grandi- 
florus and Ampelopsis hederacea, which do not revolve. 
It is not necessarily related to the curling of the tips 
round a support, as we see with the Ampelopsis and 
Bignonia capreolata, in which the development of 
adherent discs suffices to cause spiral contraction. 
Yet in some cases this contraction seems connected 
with the curling or clasping movement, due to contact 
with a support; for not only does it soon follow this 
act, but the contraction generally begins close to the 
curled extremity, and travels downwards to the base. 
If, however, a tendril be very slack, the whole length 
almost simultaneously becomes at first flexuous and 
then spiral. Again, the tendrils of some few plants 
