SPONTANEOUS MOVEMENTS IN PLANTS. 837 
the air, as if, as Darwin expresses it, it were searching for a 
support. I do not here discuss the question whether this 
habit may be the result of a tendency transmitted and en¬ 
hanced through thousands of generations; the movement 
itself is, in the individual plant, entirely “ spontaneous” in 
every sense of the term; that is, is not the necessary result of 
known physical laws acting upon the individual. Darwin’s 
paper “On the Movements and Habits of Climbing Plants,” 
published in the 4 Journal of the Linnean Society/ contains a 
number of the most interesting observations on this class of 
plants ; and the language employed is everywhere suggestive 
of some hidden sentient controlling power in the plant itself. 
The same purpose as that served by a climbing stem is 
answered in other plants, as the vine, Virginian creeper, and 
passion-flower, by tendrils; and the phenomena of sponta- 
neous motion in tendrils are, if possible, still more curious. 
Some tendrils display the same power of rotatory motion 
possessed by the extremities of the shoots of climbing plants, 
others do not revolve, but are sensitive, bending to the touch. 
The curling movement consequent on a single touch con¬ 
tinues to increase for a considerable time, then ceases; after 
a few hours the tendril uncurls itself, and is again ready for 
action. A tendril will thus show a tendency to curl round 
any object with which it comes into contact, with the singu¬ 
lar exception that it will seldom twine itself round another 
tendril of the same plant. It is also very curious that with 
some exceedingly sensitive plants, the falling of drops of rain 
on the tendril will produce no effect whatever. The mode 
in which a tendril of a Bignonia catches hold of a support is 
thus described by Darwin:—“The main petiole is sensitive 
to contact with any object; even a small loop of thread after 
two days caused one to bend upwards. The whole tendrils 
are likewise sensitive to contact. Hence, when a shoot 
grows through branched twigs, its revolving movement soon 
brings the tendril into contact with some twig, and then all 
three c toes’ bend (or sometimes one alone), and, after 
several hours, seize fast hold of the twig, exactly like a bird 
when perched.” The Virginian creeper has another mode of 
attaching itself to a wall or other solid support, by the forma¬ 
tion at the extremities of the branches of the tendril, of little 
disks or cushions, very similar to the disks on the foot of the 
house-fly by which it is enabled to attach itself to our win¬ 
dows and to walk along the ceiling. These disks secrete a 
glutinous fluid which attaches the tendril to the support 
with such strength that it is often impossible to detach it 
without destroying the tendril or even removing a portion of 
