But be sure to examine one of these pitchers if you possibly can, and then you will understand better how the whole thing is managed.
The leaf in this picture (Fig. [153]), for it is a leaf, you cannot find in our North American swamps. It grows on a plant called Nepenthes, a plant which lives in hot countries far from the United States.
Fig. 153
The leaf in the picture is full grown, and all ready for its work of trapping animals. Before it was old enough to do this, the lid which is now lifted was laid nicely across the opening to the pocket, and so prevented any unseasonable visits.
Sometimes these pockets are so large as to be able to hold and to hide from sight a pigeon. They are gayly colored, and the rim around their border is covered with a sugary, tempting juice. So you can guess that the animals in search of nectar are not slow in accepting the invitation offered by color and sweets, and that some of these are imprudent enough to venture across the sticky edge. In this event they are pretty sure to lose their footing on the slippery inner surface of the pocket, and to fall into the watery liquid with which it is filled. Even if they do not slip immediately, their efforts to crawl back over the rim are defeated by a row of teeth such as you see in the picture.
The liquid at the bottom of the leaf is not rain water, as in the pitcher plant. It is given out by the leaf itself; and it contains an acid which dissolves the animals’ bodies, so that their more nourishing parts can easily be taken in by certain little cells which line the lower part of the pocket, and which have been brought up to this work.
Fig. 154
The next picture (Fig. [154]) shows you a water plant. It is called the “bladderwort,” because of the little bags or bladders which you see growing from the branches under water. The little bladders are traps set for water animals, which swim into them in their wish, perhaps, to escape some enemy. But they are quite unable to swim out again; for the door into the bladder is transparent, and looks like an open entrance with a nice hiding place beyond. It opens easily from the outside, but is so arranged that it will not open from within. So when the poor little animal hurriedly swims into what seems to it a cozy resting spot, and draws a long breath of relief at getting safe inside, it is hopelessly caught, and must slowly starve to death, for there is no chance of escape. It may live for nearly a week in this prison; but at last it dies. Its body decays, and is taken in as food by the cells set apart for that purpose.