When we consider the high degree to which ants carry the principle of co-operation, it is evident that they must have some means of intercommunication. This is especially true of the Ecitons, which so strangely mimic the tactics 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 the capture and plunder of other insects, &c., 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 component individuals of which play the part of scouts, branching off in various directions, and searching about with the utmost activity for insects, grubs, &c., over every log, under every fallen leaf, and in every nook and cranny where there is any chance of finding prey. When their errand is completed, they return into the main column. If the prey found is sufficiently small for the scouts themselves to manage, it is immediately seized, and carried back to the main column; but if the amount is too large for the scouts to deal with alone, messengers are sent back to the main column, whence there is immediately despatched a detachment large enough to cope with the requirements.... On either side of the main column there are constantly running up and down a few individuals of smaller size and lighter colour than the other ants, which seem to play the part of officers; for they never leave their stations, and while running up and down the outsides of the column, they every now and again stop to touch antennæ with some member of the rank and file, as if to give instructions. When the scouts discover a wasps’-nest in a tree, a strong force is sent out from the main army, the nest is pulled to pieces, and all the larvæ carried to the rear of the army, while the wasps fly around defenceless against the invading multitude. Or, if the nest of any other species of ant is found, a similarly strong force—or perhaps the whole army—is deflected towards it, and with the utmost energy the innumerable insects set to work to sink shafts and dig mines till the whole nest is rifled of its contents. In these mining operations the ants work with an extraordinary display of organized co-operation; for those low down in the shafts do not lose time by carrying up the earth which they excavate, but pass the pellets to those above; and the ants on the surface, when they receive the pellets, carry them—with an appearance of forethought which quite staggered Mr. Bates—only just far enough to insure that they shall not roll back again into the shaft, and, after depositing them, immediately hurry back for more. But there is not a rigid (or merely mechanical) division of labour: the work seems to be performed by intelligent co-operation amongst a host of eager little creatures; for some of them act at one time as carriers of pellets, and