Nature's Teachings. John George Wood
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Название: Nature's Teachings
Автор: John George Wood
Издательство: Public Domain
Жанр: Природа и животные
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Our space being valuable, we are not able to give many examples of Baited Traps, whether in Art or Nature.
The most familiar example of this trap is the common Mouse-trap, the most ordinary form of which is shown at the right hand of the illustration on page 96. In all the varieties of these traps, whether for mice or rats, the prey is induced to enter by means of some tempting food, and then is secured or killed by the action of the trap. Sometimes these traps are made of considerable size for catching large game, and in Africa are employed in the capture of the leopard, in India for taking both tigers and leopards, and in North America for killing bears.
We have already noticed one instance of a bait in the Angler-fish, described in page 92, but in this case the bait serves only for attraction, and the trap, or mouth, is not acted upon by the prey.
There are, however, many examples in the botanical world, where the plant is directly acted upon by the creature which is to be entrapped, such being known by the now familiar term “Carnivorous Plants.” Of these there is a great variety, but under this head I only figure two of them.
The plant on the right hand is the Venus Fly-trap (Dionea muscipula), which is common in the Carolinas. The leaves of this plant are singularly irritable, and when a fly or other insect alights on the open leaf, it seems to touch a sort of spring, and the two sides of the leaf suddenly collapse and hold the insect in their grasp. The strange point about it is, that not only is the insect caught, but is held until it is quite digested, the process being almost exactly the same as if it had been placed in the stomach of some insect-eating animal.
So carnivorous, indeed, is the Dionea, that plants have been fed with chopped meat laid on the leaves, and have thriven wonderfully. Experiments have been tried with other substances, but the Dionea would have nothing to do with them. The natural irritability of the leaves caused them to contract, but they soon opened and rejected the spurious food.
On the left is the Cephalotus. This plant, instead of catching the insect by the folding of the leaf, secures it by means of a sort of trap-door at the upper end. The insect is attracted by the moisture in the cup, and, as soon as it enters, the trap-door shuts upon it, and confines it until it is digested, when the door opens in readiness to admit more prey.
By a natural transition we pass to those traps which secure their prey by means of adhesive substances.
With us, the material called “birdlime” is usually employed. This is obtained from the bark of the holly, and is of the most singular tenacity. An inexperienced person who touches birdlime is sure to repent it. The horrid stuff clings to the fingers, and the more attempts are made to clear them, the more points of attachment are formed. The novice ought to have dipped his hands in water before he touched the birdlime, and then he might have manipulated it with impunity.
The most familiar mode of using the birdlime is by “pegging” for chaffinches.
In the spring, when the male birds are all in anxious rivalry to find mates, or, having found them, to defend them, the “peggers” go into the fields armed with a pot of birdlime and a stuffed chaffinch set on a peg of wood. At one end of this peg is a sharp iron spike. They also have a “call-bird,” i.e. a chaffinch which has been trained to sing at a given signal.
When the “peggers” hear a chaffinch which is worth taking, they feel as sure of him as if he were in their cage. They take the peg, and stick it into the nearest tree-trunk. Round the decoy they place half-a-dozen twigs which have been smeared with birdlime, and arrange them so that no bird flying at the decoy can avoid touching one of them.
The next point is, to order the call-bird to sing. His song is taken as a personal insult by the chaffinch, which is always madly jealous at this time of year. Seeing the stuffed bird, he takes it for a rival, dashes at it, and touches one of the twigs. It is all over with him, for the more he struggles and flutters, the tighter is he bound by the tenacious cords of the birdlime, and is easily picked up by the “pegger.”
Even the fierce and powerful tiger is taken with this simple, but terrible means of destruction. It is always known by what path a tiger will pass, and upon this path the native hunter lays a number of leaves smeared with birdlime. The tiger treads on one of them, and, cat-like, shakes his paw to rid himself of it. Finding that it will not come off, he rubs his paw on his head, transferring the leaf and lime to his face.
By this time he is in the middle of the leaves, and works himself into a paroxysm of rage and terror, finishing by blinding himself with the leaves that he has rubbed upon his head. The hunters allow him to exhaust his strength by his struggles, and then kill him, or, if possible, capture him alive.
Both these scenes are represented on the right hand of the illustration.
On the left hand are several examples of natural birdlime, if we may use the term. The upper represents the Ant-bear, or Great Ant-eater. This animal feeds in a very curious manner. It goes to an ant-hill, and tears it open with its powerful claws. The ants, of course, rush about in wild confusion. Now, the Ant-eater is provided with a long, cylindrical tongue, which looks very like a huge earth-worm, and which is covered with a tenacious slimy secretion. As the ants run to and fro, they adhere to the tongue, and are swept into the mouth of their destroyer.
Below the Ant-eater is the common Drosera, or Sundew, one of our British carnivorous plants. It captures insects, just as has been narrated of the Dionea. But, instead of the leaf closing upon the insect, it arrests its prey by means of little globules of viscous fluid, which exude from the tips of the hairs with which the surface of the leaf is covered. As soon as the insect touches the hairs, they close over it, bind it down, and keep it there until it is digested. Several species of Drosera are known in England, and are found in wet and marshy places.
Another plant, the Green-winged Meadow Orchis (Orchis morio), has been known to act the part of the Drosera. A fly had contrived to push its head against the viscous fluid of the stigmatic surface, and, not being able to extricate itself, was found sticking there.
Next comes a portion of the web of the common Garden Spider (Epeira diadema). We have already treated of this web as a net, and we will now see how it comes within the present category.
In the web of the spider there are at least two distinct kinds of threads. Those which radiate from the centre to the circumference are strong and smooth, while those which unite them are much slighter, and are covered with tiny globules set at regular intervals. When the web is newly spun, these globules are found to be nearly as tenacious as birdlime, and it is by these means that an insect which falls into the web is arrested, and cannot extricate itself until the spider can seize it. After awhile the globules become dry, refuse to perform their office, and then the spider has to construct another web. So numerous are these globules that, according to Mr. Blackwall’s calculations, an ordinary net contains between eighty and ninety thousand. СКАЧАТЬ