Читать книгу The Circle of Knowledge: A Classified, Simplified, Visualized Book of Answers - Various - Страница 201

One of the most singular instances of this is to be seen in a little plant which is only found growing in the bogs of the Carolinas. This has been rather cynically called the Venus Fly Trap (Dionæa muscipula), a fanciful name which hides its cruel practices. Few plants have adopted a more certain plan than the Dionæa. Every leaf which the plant produces is the most perfect device for the securing of prey that could be imagined.

The mechanical construction of this remarkable vegetable trap is somewhat on the following lines. The leaf is borne at the end of a curiously broad stalk, and is divided into two lobes; these are joined together by a hinge-like arrangement. The outside borders of the lobes are fringed with from a dozen to twenty long teeth. When fully expanded the leaf lies back on the moss amid which the plant grows.

If we examine the inside surface of the lobes we shall see that these are in the middle colored a rosy red. Just at this point will be discovered three hairs arranged in triangular fashion.

It is interesting to consider the actual manner in which the plant carries out its fly-catching.

As is well known, bright colors have a great attraction for insects. In this case it is apparently the red areas on the lobes of the leaves which possess such an attraction for insects of all kinds. Possibly they secrete a sweet substance, but this is not definitely known. All goes on well as long as the creatures avoid doing one thing; unhappily, this they are almost certain to do sooner or later. Nothing happens unless the insect brushes up against one of the hairs previously mentioned as being on the surface of the lobes. The succeeding happenings are disastrous for the fly.

With really astonishing rapidity the sides of the leaf snap together so that the spines on the borders of the lobes meet. Thus, in a very brief time a most perfect little cage is devised from which any sort of escape is absolutely impossible. During the next half hour the sides draw in still closer, so that the spines overlap. At this stage the leaf pours out a copious discharge of digestive fluid, which enables the plant to make use of the nutritious element in the fly.

CRUEL PLANTS THAT ENTRAP AND KILL ANIMALS

The light streaming through the transparent spaces induces the prisoner to waste its strength in a vain effort to escape through them.	Once below the inside edge, escape is almost impossible. Pitchers have been found almost full of flies and other insects.
Absorbed in the delights of feasting on the nectar of the Nepenthes, the insect wanders with fatal ease down the fluted rim.	The fruits of the Martynia fasten themselves to passing animals that sometimes get the hooks caught in their mouths and die a dreadful death.

After an interval of several days the leaf of the Dionæa opens and allows the hard carcass of the fly to roll away. The plant is then ready for another meal, and unable to realize the fate which is in store for it, another fly falls a victim. Quite often the Venus Fly Trap is able to capture large insects.