90 TENDRIL-BEARERS. Cuap. LIL. 
and thicken, and ultimately becomes wonderfully 
strong, in the same manner as the petioles of leaf- 
climbers. If the tendril catches nothing, it first 
slowly bends downwards, and then its power of clasping 
is lost. Very soon afterwards it disarticulates itself 
from the petiole, and drops off like a leaf in autumn. 
I have seen this process of disarticulation in no other 
tendrils, for these, when they fail to catch an object, 
merely wither away. 
Bignonia venusta.—The tendrils differ considerably 
from those of the previous species. The lower part, 
or tarsus, is four times as long as the three toes; these 
are of equal length and diverge equally, but do not 
lie in the same plane; their tips are bluntly hooked, 
and the whole tendril makes an excellent grapnel. The 
tarsus is sensitive on all sides; but the three toes are 
sensitive only on their outer surfaces. ‘The sensitive- 
ness is not much developed; for a slight rubbing with 
a twig did not cause the tarsus or the toes to become 
curved until an hour had elapsed, and then only 
in a slight degree. Subsequently they straightened 
themselves. Both the tarsus and toes can seize well 
hold of sticks. If the stem is secured, the tendrils are 
seen spontaneously to sweep large ellipses; the two 
opposite tendrils moving independently of one another. 
I have no doubt, from the analogy of the two following 
allied species, that the petioles also move spontaneously ; 
but they are not irritable like those of B. unguis and 
B. Tweedyana. The young internodes sweep large 
circles, one being completed in 2 hrs. 15 m., and 
