Cuap. IL. : CLEMATIS, 55 
with which it is left in contact. The inferior surface 
of the rectangularly bent terminal portion (carrying 
the terminal leaflet), which forms the inner side of the 
end of the hook, is the most sensitive part; and this 
portion is manifestly best adapted to catch a distant 
support. To show the difference in sensibility, I 
gently placed loops of string of the same weight (in 
“one instance weighing only -82 of a grain or 53:14 mg.) 
on the several lateral sub-petioles and on the terminal 
one; in a few hours the latter was bent, but after 
24 hrs. no effect was produced on the other sub-petioles. 
Again, a terminal sub-petiole placed in contact with a 
thin stick became sensibly curved in 45m., and in 
lhr. 10m. moved through ninety degrees; whilst 
a lateral sub-petiole did not become sensibly curved 
until 3hrs. 30m. had elapsed. In all cases, if the 
sticks are taken away, the petioles continue to move 
during many hours afterwards; so they do after a 
slight rubbing ; but they become straight again, after 
about a day’s interval, that is if the flexure has not 
been very great or long continued. 
The graduated difference in the extension of the 
sensitiveness in the petioles of the above-described 
species deserves notice. In C. montana it is confined 
to the main petiole, and has not spread to the sub- 
_ petioles of the three leaflets; so it is with young plants 
of C. calycina, but in older plants it spreads to the 
three sub-petioles. In C. viticella the sensitiveness has 
spread to the petioles of the seven leaflets, and to the 
subdivisions of the basi-lateral sub-petioles. But in 
