Berton Mercer.

CARNIVOROUS PLANTS.

This name has been given to certain plants which have developed the curious habit of capturing insects and using them for food. This behavior seems at first sight most unplantlike, but it is discovered that the actual food of all plants is practically the same as that of animals. The chief peculiarity of carnivorous plants, therefore, does not lie in the food which they use, but in the methods which they have worked out for securing it.

They are all green plants, and hence are able to make food for themselves, but they live in surroundings which are poor in some of the material which they need in the manufacture of food, so that they have learned to supplement their food by capturing insects or other small animals. When it was discovered that these plants not only captured insects, but secreted substances for digesting them, it was thought to be a very astonishing fact. It is found, however, that all plants have digestive substances to act upon their food materials, and that animals are not peculiar in this regard. It would seem, therefore, that the use of such food as the bodies of insects and the digesting of this food are not facts which are peculiar to carnivorous plants, but belong to all plants as well.

It is interesting, however, to observe the various devices which plants have adapted for capturing their prey, and it is these various devices which form the subject of this paper.

Prominent among the carnivorous plants are the pitcher plants, whose leaves form tubes, or urns, or pitchers of various forms, which contain water, and to which insects are attracted and drowned. There is a very common pitcher plant in our northern bogs, in whose urn-like leaves insects are found drowned, but which does not have such elaborate arrangements for their capture as other forms. Perhaps the most famous of the pitcher plants is one which is common throughout the southern states. The leaves are shaped like slender hollow cones, and rise in a tuft from the swampy ground. The mouth of this conical urn is overarched and shaded by a hood in which are translucent spots like small windows. Around the mouth of the urn are glands which secrete a sweet liquid, and drops of this nectar form a trail down the outside of the urn. Inside, just below the rim of the urn, is a glazed zone so smooth that insects cannot walk upon it. Below the glazed zone is another zone thickly set with stiff downward-pointing hairs, and below this is the liquid in the bottom of the urn. If a fly is attracted by the nectar drops on this curious leaf, it naturally follows the trail up to the rim of the urn where the nectar is abundant. If it attempts to descend into the urn it slips on the glazed zone and falls into the water; and if it attempts to escape by crawling up the side of the urn, the thick-set, downward-pointing hairs prevent. If it seeks to fly away from the rim it flies towards the translucent spots in the hood, which look like the way of escape, as the direction of entrance is in the shadow of the hood. Pounding against the hood the fly falls into the water. This southern pitcher plant is known as a great fly catcher, and is frequently used for this purpose in the south.

PRESENTED BY LINCOLN PARK COMMISSIONERS.PITCHER PLANT.
(Nepenthes.)		COPYRIGHT 1900, BY
A. W. MUMFORD, CHICAGO.

The very largest of the pitcher plants is one which grows in the swamps of California, whose leaves sometimes become as much as two or three feet high, the huge pitchers forming the most capacious receptacle for insects of all kinds and sizes. Its general plan is like that of the southern pitcher plant described above, in that it has an overarching hood with translucent spots, and a trail of nectar which leads to the dangerous rim. It has become further elaborated, however, in that the hood extends into a gaudy fish-like appendage, whose colors and flapping serve to attract the flying as well as the creeping insects. The pitcher, also, instead of being straight, is spirally twisted, and has a wing-like expansion which serves as a guide in the spiral ascent to the rim, and leads the victim with definiteness and certainty to the region of danger. The fish-tail appendage is also smeared with the nectar secretion, so that any flying insect lighting upon it is enticed under the overshadowing arch and is almost sure of capture.