CHAP. 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 1 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 been 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 

 iays. Two other leaves remained closed over bits of 



