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Page:Popular Science Monthly Volume 19.djvu/842

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THE POPULAR SCIENCE MONTHLY.

is therefore spent in running backward and forward upon this semi-diagonal of the square, carrying in food and feeding Class I. Ko black ant is ever seen on the eastern diagonal, and no yellow ant is ever seen on the western; but each keeps to his own separate station, and here works with a steadfastness and apparent adherence to discipline which are not less remarkable than those exhibited by the sentries. The western hole before mentioned seems to be intended only as a ventilating shaft; it is never used as a gateway.

Section of the nest reveals, besides passages and galleries, a small chamber, across which is spread, like a spider's web, a network of squares spun by the insects. In each of these squares, supported by the web, sits one of the honey-secreting ants (II). Here the honey makers live in perpetual confinement, and receive a constant supply of flowers, pollen, etc., which is continually being brought them by I, and which, by a process of digestion and secretion, they convert into honey. It is particularly noteworthy that in this truly wonderful exhibition of social coöperation the black and yellow workers appear to belong to two distinct genera; for hitherto this is the only case known of two distinct species of animals coöperating for a common end.

Ecitons.—We have lastly to consider the most astonishing insects, if not the most astonishing animals, in the world. These are the so called "foraging," or, as they might more appropriately be called, the military ants of the Amazon. They belong to several species of the same genus, and have been carefully watched by Bates, Belt, and other naturalists. The following facts must therefore be regarded as fully established:

Eciton legionis moves in enormous armies, and everything that these insects do is done with the most perfect instinct of military organization. The army marches in the form of a rather broad and regular column, hundreds of yards in length. The object of the march is to capture and plunder other insects, etc., for food, and, as the well-organized host advances, its devastating legions set all other terrestrial life at defiance. From the main column there are sent out smaller lateral columns, the composing individuals of which play the part of scouts, branching off in various directions, and searching about with the utmost activity for insects, grubs, etc., over every log and under every fallen leaf. If prey is found in sufficiently small quantities for them to manage alone, it is immediately seized and carried to the main column, but, if the amount is too large for the scouts themselves to deal with, messengers are sent back to the main column, whence there is immediately dispatched a detachment large enough to cope with the requirements. Insects or other prey which, when killed, are too large for single ants to carry, are torn in pieces, and the pieces conveyed back to the main army by different individuals. Many insects in trying to escape run up bushes and shrubs, where they are