Gap. XIII. MANNER OF CAPTURING INSECTS. 309 
pensable for the capturing of insects. These two move- 
ments, excited by two such widely different means, 
are thus both well adapted, like all the other 
functions of the plant, for the purposes which they 
subserve. 
There is another wide difference in the action of 
leaves which enclose objects, such as bits of wood, 
cork, balls of paper, or which have had their filaments 
merely touched, and those which enclose organic 
bodies yielding soluble nitrogenous matter. In the 
former case the leaves, as we have seen, open in under 
24 hrs. and are then ready, even before being fully 
expanded, to shut again. But if they have closed 
over nitrogen-yielding bodies, they remain closely 
shut for many days; and after re-expanding are 
torpid, and never act again, or only after a consider- 
able interval of time. In four instances, leaves after 
catching insects never reopened, but began to wither, 
remaining closed—in one case for fifteen days over 
a fly; in a second, for twenty-four days, though 
the fly was small; in a third for twenty-four days over 
a woodlouse ; and in a fourth, for thirty-five days over 
a large Tipula. In two other cases leaves remained 
closed for at least nine days over flies, and for how 
many more I do not know. It should, however, be 
added that in two instances in which very small 
insects had been naturally caught the leaf opened 
as quickly as if nothing had beet caught ; and I 
suppose that this was due to such small insects not 
having been crushed or not having excreted any 
animal matter, so that the glands were not excited. 
Small angular bits of albumen and gelatine were 
placed at both ends of three leaves, two of which 
remained closed for thirteen and the other for twelve 
days. Two other leaves remained closed over bits of 
