Page:Popular Science Monthly Volume 23.djvu/50

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account in the so-called "oyster-schools" of France. The distance from the coast to Paris being too great for the newly-dredged oysters to travel without opening their shells, they are first taught in the schools to bear a longer and longer exposure to the air without gaping, and when their education in this respect is completed, they are sent on their journey to the metropolis, where they arrive with closed shells and in a healthy condition.

The social life of ants has many parallels to that of the barbarous races of human beings. Thus, the habit of making slaves is said to obtain among at least three species of ant. A community attacks a nest of another species in a body; there is a great fight with much slaughter, and, if victorious, the slave-makers carry off the pupae of the vanquished nest in order to hatch them out as slaves. When the pupae hatch out in the nest of their captors, the young slaves begin their life of work, and seem to regard their masters' home as their own; for they never attempt to escape, and they fight no less keenly than their masters in defense of the nest. In the nests of Formica sanguinea the comparatively few captives are kept as household slaves. They never leave the nest, and so all the out-door work of foraging, slave-capturing, etc., is performed by the masters.

F. rufescens, on the other hand, assigns a much larger share of labor to the slaves. In this species the males and fertile females do no work of any kind, and the workers, or sterile females, though most energetic in capturing slaves, do no other kind of work. Therefore the whole community is absolutely dependent upon its slaves. Huber shut up thirty masters without a slave and with abundance of their favorite food, and also with their own larvæ and pupæ as a stimulus to work; but they could not feed even themselves, and many died of hunger. He then introduced a single slave, and she at once set to work, fed the surviving masters, attended to the larvæ, and made some cells.

A predatory expedition of ants for capturing slaves, or robbing the storehouse of another nest, marches out in a close column numbering from a few hundreds to several thousands. The army is guided to its destination, which may be an hour's march distant, by several ants who run from side to side with heads down, evidently finding their way by scent. A marauding excursion of the F. rufescens, or Amazons, against the F. rufibarbis, a sub-species of the F.fusca, or small black ants, took place as follows: The vanguard of the robber army found that it had reached the neighborhood of the hostile nest more quickly than it had expected; for it halted suddenly and decidedly, and sent a number of messengers which brought up the main body and the rear-guard with incredible speed. In less than thirty seconds the whole army had closed up, and hurled itself in a mass on the dome of the hostile nest. This was the more necessary, as the rufibarbes during the short halt had discovered the approach of the enemy, and