Sometimes, when they are on a marauding expedition, they construct a tunnel in a very curious manner, their own bodies supplying the materials. The reader must know that there are several classes of these insects, varying in size from that of a huge earwig to that of the little red ant of our gardens. The largest class seem to care little about the sunshine, the protection being mostly needed by the workers. The following is Dr. Savage’s account of their proceedings:—
“In cloudy days, when on their predatory excursions, or migrating, an arch for the protection of the workers is constructed of the bodies of their largest class. Their widely extended jaws, long, slender limbs, and projecting antennæ, intertwining, form a sort of network that seems to answer well their object.”
“Whenever an alarm is given, the arch is instantly broken, and the Ants, joining others of the same class on the outside of the line, who seem to be acting as commanders, guides, and scouts, run about in a furious manner in pursuit of the enemy. If the alarm should prove to be without foundation, the victory won, or danger passed, the arch is quickly renewed, and the main column marches forward as before, in all the order of an intellectual military discipline.”
How they should be able to direct their course, and to chase an enemy, is not easy to understand; for, as far as is known, they are absolutely blind, not even an indication of an eye being seen.
The Suspension-bridge.
The mention of these Ants brings us to another point in architecture. We have already seen that they can not only build arched tunnels, but also can form their own bodies into arches, and we shall presently see how they can form themselves into Suspension-bridges. We will, however, first take the Suspension-bridge, and its vegetable origin, before passing to the animal.
I have little if any doubt that the modern Suspension-bridge, with all its complicated mathematical proportions, was originally suggested by the creepers of tropical climates. There are few points in a tropical forest, no matter in what part of the world, more striking than the wonderful development of the creeping plants. The trees are very much like those of our own forests, and are in no way remarkable, but the creeping plants form the chief feature of the woods.
They extend themselves to unknown lengths, crawling up to the very summit of a lofty tree, hanging down to the very ground, if not caught by a midway branch, running along the earth, making their way up another tree, and so on ad infinitum. They interlace with each other, forming almost impenetrable thickets, as has already been mentioned while treating of Nets, and there is scarcely a tree that is not connected with its neighbour by means of these wonderful creeping plants.
Of course the monkey tribes make great use of them in passing from one tree to another, thus being able to avoid the ground, which is never to a monkey’s liking. Man, therefore, copies the example of the monkey, and makes use, either of the creepers themselves, or of ropes stretched from tree to tree in imitation of them.