Cav. TV. PASSIFLORACEA, 157 
quickly when nearly full-grown. A plant was placed 
in front of a window, and, as with twining stems, the 
light accelerated the movement of the tendril in one 
direction and retarded it in the other; the semicircle 
towards the light being performed in one instance in 
15 m. less time and in a second instance in 20 m. less time 
than that required by the semicircle towards the dark 
end of the room. Considering the extreme tenuity of 
these tendrils, the action of the light on them is 
remarkable. The tendrils are long, and, as just stated, 
very thin, with the tip slightly curved or hooked. 
The concave side is extremely sensitive to a touch— 
even a single touch causing it to curl inwards; it 
subsequently straightened itself, and was again ready 
to act. A loop of soft thread weighing 7;th of a grain 
(4:625 mg.) caused the extreme tip to bend; another 
time I tried to hang the same little loop on an inclined 
tendril, but three times it slid off; yet this extra- 
ordinarily slight degree of friction sufficed to make the 
tip curl. The tendril, though so sensitive, does not 
move very quickly aftera touch, no conspicuous move- 
ment being observable until 5 or 10m. had elapsed. 
The convex side of the tip is not sensitive to a touch 
or to a suspended loop of thread. On one occasion I 
observed a tendril revolving with the convex side of 
the tip forwards, and in consequence it was not able 
to clasp a stick, against which it scraped; whereas 
tendrils revolving with the concave side forward, 
promptly seize any object in their path. 
Passiflora quadrangularis—This is a very distinct 
