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rare. In the first case, with Passifora, the younger tendril 
may be firmly held by the coiling of the older one around it 
but nevertheless does not itself coil, though if the base of the 
coiled tendril be pulled upon, a distinct curvature, which soon 
straightens again, is produced in the free portion of the youn- 
ger tendril, the latter being insensible to the steady pressure 
of the tendril coiled around it, but responding readily to a 
sudden and irregularly distributed increase in that pressure. 
With Lchinocystis lobata, Bignonia venusta, Vitis discolor and 
V. pallida, when two such tendrils come into contact, the coiling 
of the older tendril is as a general rule followed at once or 
after a short time by the coiling of the younger imprisoned one. 
In Vitis discolor, V. pallida, Bignonia albolutea and B. speciosa, 
the tendrils never seem in nature to coil around one another, 
but they are fairly readily sensitive to self contact. On bringing 
the tendrils together, contact curvatures are produced it the 
irritable surfaces are stimulated, but almost always as Cir- 
Cumnutation contines, the tendrils separate with or without a 
previous straightening. If several of the tendrils are interlocked 
with one another, so that a relatively strong pressure is exerted 
on the surfaces in contact, the curvatures may continue and 
the tendrils finally twine permanently together. 
In Bignonia venusta and B. littoralis with rather thin smooth and 
slender tendrils, these are rarely, whereas in Amphilobium mutist 
Smilax prolifera. 8. anceps and 8. ovalifolia with fairly thick 
and rigid tendrils they are frequently, found coiling together 
in nature and are markedly irritable to contact with one 
another. In Smilax owing to the tendrils being much more 
than half the length of the internodes they frequently catch 
one another but generally separate again, it being only when 
the direction of the circumnutation is such as to keep them 1 
contact for a sufficient length of time and when the most 
irritable surfaces are in contact and exerting slight but distinct 
pressure on one another, that the tendrils coil permanently | 
around one another, and this may happen with the pair of 
tendrils arising from the same leaf stalk. 
