pursued from branch to branch and twig to twig by their remorseless enemies, till, on arriving at some terminal ramification, they must either submit to immediate capture by their pursuers or drop down amid the murderous hosts beneath. As already stated, all the spoils which are taken by the scouts, or by the detachments sent out in answer to their demands for assistance, are immediately taken back to the main army or column. When they arrive there, they are conveyed to the rear of that column by two smaller columns of carriers, which are constantly running in two double rows (one of each being laden and the other not) on either side of the main column. On either side of the main column there are also constantly running up and down a few individuals of smaller size, lighter color, and having larger heads than the other ants. These appear to perform the duty of officers, for they never leave their stations, and, while actively running up and down the outsides of the column, they seem intent only on maintaining order in the march—stopping every now and then to touch some member of the rank and file with their antennæ, as if giving directions.
When the scouts discover a wasp's nest in a tree, a strong force is sent out from the main army, the nest is pulled to pieces, and all the larvæ in the nest are carried by the carrier-columns to the rear of the army, while the wasps fly around defenseless against the invading multitudes. Or, if the nest of any other species of ant is found, a similarly strong force is sent out, or even the whole army may be deflected toward it, when 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 Ecitons work with an extraordinary display of organized coöperation; for those low down in the shafts do not lose time by carrying up the earth which they excavate, but pass on the pellets to those above, and the ants on the surface, when they receive the pellets, carry them only just far enough to insure that they shall not roll back again into the shaft, and, after having deposited them at a safe distance, immediately hurry back for more.
The Ecitons have no fixed nest themselves, but live, as it were, on a perpetual campaign. At night, however, they call a halt and pitch a camp. For this purpose they usually select a piece of broken ground, in the interstices of which they temporarily store their plunder. In the morning the army is again on the march, and before an hour or' two has passed not a single ant is to be seen where thousands and millions had previously covered the ground.
The habits of E. humana and E. drepanophora are in general similar to those of the species just described. The latter, however, march in a narrower column (only four to six deep), which is therefore proportionally longer—sometimes extending to over half a mile. Bates tried the effect of interfering with a column of this species by
