The most common pitcher plants of the tropics are the Nepenthes, one of which is shown in our illustration. It will be noticed that each leaf when fully formed consists of three distinct regions, namely, the leaf-like blade, which is continued into a tendril which coils around a support, and the tendril in turn ends in a curiously formed pitcher, which has a more or less complete lid. These pitchers are often mottled with bright colors, and as they swing at the ends of the tendrils they seem to attract the attention of roving insects. Around the rim of the pitcher a very definite row of glands may be observed, which secrete the nectar to which the insects are attracted. The arrangements within the pitcher are such as have been described for the ordinary pitcher plant. These pitchers of Nepenthes are usually found containing insects, and often very many of them, whose bodies are being slowly digested and the products absorbed by the plant.

Another group of carnivorous plants consists of the sun-dews which grow in swampy regions and are quite common in our sphagnum swamps. While the pitcher plants depend upon luring insects to their death by drowning, the sun-dews depend upon stickiness. The leaves form small rosettes on the ground and are of various shapes. In one of the most common forms the leaf blade is round, and the margin is beset by prominent bristle-like hairs, each with a globular gland at its tip. Shorter gland-bearing hairs are scattered over the inner surface of the blade. All of these glands secrete a clear sticky fluid which hangs to them in drops like dew drops, and since these dewdrops are not dispelled by the sun, the plants have been called the sun-dews, If a small insect, in flying or creeping across the plant, happens to touch one of the sticky drops it becomes entangled, and then there follows a curious scene. If the insect is small, the single bristle-like hair, in whose sticky drop it has become entangled, will begin to bend inwards and will finally press the captured insect down upon the body of the leaf where the short glandular hairs receive it.

If the insect is strong enough, however, to escape from a single sticky drop, neighboring hairs will bend toward the one which has captured the insect, and by adding their mite of strength and glue, succeed in detaining it until they all bend inwards and press it down upon the leaf. In some cases the whole half of a leaf will roll inwards in this attempt to secure an insect. In this position the captured insect is gradually digested and its nutritive substances absorbed.

Perhaps the most famous and remarkable of the fly-catching plants is the Venus fly-trap, known only in swamps near Wilmington, North Carolina. This fly-trap does not depend upon drowning the insects, or upon sticking them fast, but upon its quickness of movement. Of course this seems most wonderful in plants, which are not ordinarily endowed with powers of quick motion. Dionaea, for this is the name of the Venus fly-trap, has a cluster of small leaves rising from the marshy ground, just as is the case with pitcher plants and sun-dews. The lower part of the leaf is like any ordinary blade, but above becomes pinched almost in two, and then suddenly flares out again into a round blade-like expansion which is constructed like a steel trap, the two halves snapping together and the marginal bristles interlocking like the teeth of a trap. A few sensitive hair-like feelers are developed on the leaf surface, and when one of these is touched by a small flying or hovering insect, the trap snaps shut and the insect is caught.

Many interesting experiments have been performed with Dionaea to show its quickness and its recognition of suitable food material. For example, although it will snap shut at the touch of a pencil point, or any other indigestible substance, it soon opens again; while in the case of a digestible substance the trap remains closed until digestion has, taken place. It has been claimed further that when the trap has closed its bristles do not interlock closely at first, so that between the crevices very small insects may crawl out and escape. In such an event the trap opens again and waits for other prey. If this be true, it follows that the leaf does not undertake the rather long process of digestion until an insect of suitable size has been captured, one which cannot escape through the meshes of the bristles. Digestion is slow work with Dionaea as with an anaconda, being said to occupy not less than two weeks.