sand pupæ, so that during a single summer the total number of pupæ captured by this colony might be put down at forty thousand.
Forel further tried the following experiment: He kept nests of two species of slave-making ants in two separate sacks, and when he saw that an expedition of a third species (Amazons) had found a slave nest to plunder, and were fairly on their march toward it, he turned out one of his sacks upon the nest. A fight at once began between the slave-ants and sanguine ants which he had turned loose upon them. Then the vanguard of the Amazons came up; but, when they saw that the sanguines were already on the field, they drew back and awaited the approach of the main army. In close order this whole array then precipitated itself upon the already struggling host of sanguine ants. The latter, however, repulsed the attack, and the Amazons retired to reform. This done they made a second assault, which appearing as if it would end successfully, Forel, to complicate matters, poured upon the field his second sack containing the third species of slave-makers. All three species then fought together, till at last victory declared itself on the side of the Amazons. After overcoming their enemies they paused for a breathing-space before beginning the work of plunder. They then ravished the nest of the slave-ants, which, however, fought desperately, so that it seemed as though they courted death. They even followed the Amazons right up to their own nest, harassing them all the way. On arriving at the nest of the Amazons the slaves of the latter came out and assisted their masters to fight. These slaves were of two species—one being the same as that which was being plundered, so that these slaves were fighting for their masters against their own kind. Altogether, therefore, in that day's warfare there were six different species of ants engaged—three in alliance, and the rest in mutual antagonism.
The military tactics employed by the sanguine ants above mentioned are different from those employed by the Amazons. They do not seek to carry the fortress of the slave-ants by storm, but lay a regular siege, forming a complete circle round the nest, and facing it with jaws held fiercely open and antennæ thrown back. Being individually large and strong, they are able thus to confine the whole nest of slave-ants. A special guard is set upon the entrances of the nest, and this allows all slave-ants not carrying pupæ to pass, while it stops all the slave-ants which carry pupæ. The siege lasts till most of the slave-ants have thus been allowed to pass out, while all the pupæ are left behind. The forces then close in upon the entrances and completely rifle the nest of its pupæ—a few companies, however, being told off to pursue any slave-ants which may possibly have succeeded here and there in escaping with a pupa.
Wars are not confined to species of ants having slave-making habits. The agricultural ants likewise at times have fierce contests with one another. The importance of seeds to these insects, and the