Car. III. LEGUMINOSAE. 115 
curved in harmony together, owing to inequality of 
age. 
Dutrochet made no observations on the sensitiveness 
of the tendrils. These, whilst young and about an inch 
in length with the leaflets on the petiole only partially 
expanded, are highly sensitive; a single light touch 
with a twig on the inferior or concave surface near the 
tip caused*them to bend quickly, as did occasionally 
a loop of thread weighing one-seventh of a grain 
(9:25 mg.). The upper or convex surface is barely or 
not at all sensitive. Tendrils, after bending from a 
touch, straighten themselves in about two hours, and 
are then ready to act again. As soon as they begin 
to grow old, the extremities of their two or three pairs 
of branches become hooked, and they then appear to 
form an excellent grappling instrument; but this is 
not the case. For at this period they have generally 
quite lost their sensitiveness; and when hooked on to 
twigs, some were not at all affected, and others required 
from 18 hrs. to 24 hrs. before clasping such twigs; 
nevertheless, they were able to utilise the last vestige 
of irritability owing to their extremities being hooked. 
Ultimately the lateral branches contract spirally, but 
not the middle or main stem. 
Lathyrus aphaca.—This plant is destitute of leaves, 
except during a very early age, these being replaced 
by tendrils, and the leaves themselves by large stipules. 
It might therefore have been expected that the ten- 
drils would have been highly organized, but this is 
not so, They are moderately long, thin, and un- 
