Nature's Teachings. John George Wood
spikes, permits an animal to enter a passage easily, and yet prevents it from emerging.
Whether or not this principle be now employed in warfare I cannot say, but it is at all events used extensively in a small way of hunting, the best known of which is the wire Mouse-trap, one of which is shown at Fig. C on the illustration. A glance at the figure will explain the trap, even to those who have never seen it. It is composed entirely of wire, and has several round holes just above its lower edge. Each of these holes is the entrance to a conical tunnel made of wires with sharpened ends.
The mouse, being attracted by a bait placed within the trap, tries to get at it. The doomed animal soon finds its way to one of the entrances, and with little difficulty pushes itself through the tunnel. Entering, however, is one thing, and returning is another. The wire yielded easily enough in one direction, but for the mouse to force itself against the converging points is an impossible task.
Readers of the last century literature may perhaps remember, in the pages of “Peter Pindar,” a very clever and sarcastic account of the astonishment created in the mind of George III. by a mouse-trap seen accidentally in the house of a widow living at Salt Hill.
“Eager did Solomon, so curious, clap
His rare round optics on the widow’s trap,
That did the duty of a cat.
And, always fond of useful information,
Thus wisely spoke he with vociferation,—
‘What’s that? what? what? Hæ, hæ? what’s that?’
To whom replied the mistress of the house,
‘A trap, an’t please you, sir, to catch a mouse.’
‘Mouse—catch a mouse!’ said Solomon with glee;
‘Let’s see, let’s see—’tis comical—let’s see—
Mouse! mouse!’—then pleased his eyes began to roll—
‘Where, where doth he go in?’ he marvelling cried.
‘There,’ pointing to the hole, the dame replied.
‘What! here?’ cried Solomon, ‘this hole? this hole?’
Then in he pushed his finger ’midst the wire,
That with such pains that finger did inspire,
He wished it out again with all his soul.”
For my part I think that the King was quite right. If he did not know the philosophy of a mouse-trap he ought to have asked, and to have been rewarded, as in that case, by catching with a trap of his own baiting, six mice on six successive days.
At Fig. B on the same illustration is shown the simple apparatus by which crabs and lobsters are caught. The reader will see that the principle is exactly the same in both cases, the only difference being in material, the mouse-trap being made of wire, and the crab-pot of wicker.
At Fig. D is shown the common Eel-pot, or Eel-basket. In order to suit the peculiar shape of an eel, this basket is much longer in proportion to its diameter than either of the preceding traps, but it is formed on the same plan. An eel can easily pass into the basket through the conical tunnel, but it is next to impossible that it should find its way out again.
So much for Art, and now for Nature.
On the left hand of the illustration, at Fig. A, is the cocoon of the common Emperor-moth (Saturnia pavonia minor), the cocoon having been stripped of its outer envelope, so as to allow its structure to be better seen.
The reader will at once perceive that the entrance of the cocoon is guarded by an arrangement exactly like that of the above-mentioned traps, except that the cone is reversed, so as to allow of exit and to debar entrance. Guarded by this conical arrangement of stout bristly appendages, the pupa can remain in quiet during the time of its transformation, for nothing can force its way through such a defence, and yet the moth, when fully developed, can push its way out with perfect ease.
So admirably is this cocoon formed, that even after the moth has escaped, it is impossible to tell by mere sight whether or not it is within, the elastic wires closing on it after its passage.
Another modification of the same principle now comes before us. In the above-mentioned examples the arrangement of the reverted spikes is more or less conical, and they lead into a chamber. In the present instances, however, the mere reversion of the points is all that is needed.
The upper figure on the right hand represents the “Catchpoll” of the Middle Ages, an allusion to which has already been made. The reverted spikes turn on hinges, and are kept apart by springs. This beautifully formed head was attached to a long shaft, and was used for the purpose of dragging horsemen from the saddle. It was thrust at the neck of the rider, generally from behind. If a successful thrust were made, the spring-points gave way, sprang back again, and thus clasped the neck with a hold that was fatal to the rider.
Below it is the Deer-trap which is used in many parts of India, and to which allusion has already been made. The reader will see at once that if a deer should get its foot through the converging spikes, its doom is sealed, especially as there is a heavy log of wood attached to the trap by a rope.
On the left hand of the illustration are two examples of the same principle taken from Nature, one belonging to fresh and the other to salt water.
The upper figure represents the jaws of a Pike, with their terrible array of reverted teeth. The Pike, as every one knows, feeds upon other fish, and eats them in a curious manner. It darts at them furiously, and generally catches them in the middle of the body. After holding them for a time, for the purpose, as I imagine, of disabling them, it loosens its hold, makes another snap, seizes the fish by the head, and swallows it.
The Pike is so voracious that it will attack and eat fish not very much smaller than itself, for its digestion is so rapid that the head and shoulders of a swallowed fish have been found to be half digested, while the tail was sticking out of the Pike’s mouth. Unless, therefore, the teeth of the Pike were so formed as to resist any retrograde movement on the part of the prey, the fish would starve; for, lank and lean as it is, the Pike is one of the most voracious creatures in existence, never seeming able to get enough to eat, and yet, as is often found in such cases, capable of sustaining a lengthened fast.
How well adapted is this arrangement of teeth for preventing the escape of prey, any one can tell who, in his early days of angling, caught a Pike, and, after killing it, tried to extract the hook without previously propping the jaws open. If once the hand be inserted between the jaws, to get it out again is almost impossible without assistance, and often has the spectacle been exhibited of a youthful angler returning disconsolately home, with his right hand in the mouth of a Pike, and supporting the weight of the fish with his left.
The teeth of a serpent are set in a similar manner, as can be seen by reference to the illustration on page 80. An admirable example of the power of this arrangement may be seen in the jaws of our common Grass or Ringed Snake (Coluber natrix). The teeth are quite small, very short, and not thicker than fine needle-points. Yet, when once the snake has seized one of the hind-feet of a frog, all efforts to escape on the part of the latter are useless. The lower jaw is pushed forward, and then retracted, and at each movement the leg is drawn further into the snake’s mouth, until it reaches the junction.
The snake then waits quietly until the frog tries to free itself by pushing with its other foot against the snake’s mouth. That foot is then seized, the leg gradually following its companion, and in this way the whole frog is drawn into the interior of the snake. I have seen many frogs thus eaten, but never knew one to escape after it had been once seized by the snake. As these reptiles are perfectly harmless, it is easy to try the experiment by putting the finger into a snake’s mouth, when it will be found that the assistance