Cuar. I, THE EFFECTS OF REPEATED TOUCHES. 35 
cible touch to a considerable number of glands, and 
not one moved ; but these same glands, after an inter- 
val of some hours, being touched four or five times 
with a needle, several of the tentacles soon became 
inflected. 
The fact of a single touch or even of two or three 
touches not causing inflection must be of some service 
to the plant; as during stormy weather, the glands 
cannot fail to be occasionally touched by the tall 
blades of grass, or by other plants growing near; and 
it would be a great evil if the tentacles were thus 
brought into action, for the act of re-expansion takes 
a considerable time, and until the tentacles are re- 
expanded they cannot catch prey. On the other 
hand, extreme sensitiveness to slight pressure is of the 
highest service to the plant; for, as we have seen, if 
the delicate feet of a minute struggling insect press 
ever so lightly on the surfaces of two or three glands, 
the tentacles bearing these glands soon curl inwards 
and carry the insect with them to the centre, causing, 
after a time, all the circumferential tentacles to 
embrace it. Nevertheless, the movements of the 
plant are not perfectly adapted to its requirements; 
for if a bit of dry moss, peat, or other rubbish, is 
blown on to the disc, as often happens, the tentacles 
clasp it in a useless manner. They soon, however, 
discover their mistake and release such innutritious 
objects. 
It is also a remarkable fact, that drops of water fall- 
ing from a height, whether under the form of natural 
or artificial rain, do not cause the tentacles to move; 
yet the drops must strike the glands with considerable 
force, more especially after the secretion has been all 
washed away by heavy rain; and this often occurs, 
