It is remarkable that the military or driving ants of Africa exhibit precisely similar devices for the bridging of streams as the Ecitons of America, namely, by forming a chain of individuals over which the others pass. By means of similar chains they also let themselves down from trees.
But of the Ecitons another and more recent observer gives an account of a yet more remarkable device, although no doubt a development of the one just described. This observer is Herr H. Kreplin, who lived for nearly twenty years in South America as an engineer, and often had the opportunity of watching the Ecitons. He writes to Büchner under date 1876 as follows:
If the water-course be narrow, the thick-heads (officers) soon find trees, the branches of which meet on the bank of either side, and after a short halt the columns set themselves in motion over these bridges, rearranging themselves in a narrow train with marvelous quickness on reaching the farther side. But, if no natural bridge be available for the passage, they travel along the bank of the river until they arrive at a flat, sandy shore. Each ant now seizes a bit of dry wood, pulls it into the water and mounts thereon. The hinder rows push the front ones ever farther out, holding on to the wood with their feet and to their comrades with their jaws. In a short time the water is covered with ants, and when the raft has grown too large to be held together by the small creatures' strength, a part breaks off and begins the journey across, while the ants left on the bank busily pull their bits of wood into the water and work at enlarging the ferry-boat until it again breaks. This is repeated as long as an ant remains on shore.
I shall now bring these numerous instances to a close with a quotation from Belt, which reveals in a most unequivocal manner astonishing powers of observation and reason in the leaf-cutting ants of South America, the general habits of which we have already considered:
A nest was made near one of our tramways, and to get to the trees the ants had to cross the rails, over which the wagons were continually passing and repassing. Every time they came along a number of ants were crushed to death. They persevered in crossing for some time, but at last set to work and tunneled underneath each rail. One day, when the wagons were not running, I stopped up the tunnels with stones; but although great numbers carrying leaves were thus cut off from the nest, they would not cross the rails, but set to, work making fresh tunnels beneath them.
Such, then, are some of the more well-established facts regarding the intelligence of ants, and taken altogether they certainly seem to justify the remark of the most illustrious of naturalists, "The brain of an ant is one of the most marvelous atoms of matter in the world, perhaps more so than the brain of a man."—Nineteenth Century.
