For the knowledge of the existence of slavery among ants we are indebted to Huber,' and I cannot resist quoting the passage in which he records his discovery: On June 17, 1804,' he says, while walking in the environs of Geneva, between four and five in the evening, I observed close at my feet, traversing the road, a legion of Rufescent ants.

They

'They moved in a body with considerable rapidity and occupied a space of from eight to ten inches in length, by three or four in breadth. In a few minutes they quitted the road, passed a thick hedge, and entered a pasture ground, where I followed them. wound along the grass without straggling, and their column remained unbroken, notwithstanding the obstacles they had to surmount. At length they approached a nest, inhabited by dark ash-coloured ants, the dome of which rose above the grass, at a distance of twenty feet from the hedge. Some of its inhabitants were guarding the entrance; but, on the discovery of an approaching army, darted forth upon the advanced guard. The alarm spread at the same moment in the interior, and their companions came forth in numbers. from their underground residence. The Rufescent ants, the bulk of whose army lay only at the distance of two paces, quickened their march to arrive at the foot of the ant-hill; the whole battalion, in an instant, fell upon and overthrew the ash-coloured ants, who, after a short but obstinate conflict, retired to the bottom of The Natural History of Ants, by M P Huber, p 249.

their nest. The Rufescent ants now ascended the hillock, collected in crowds on the summit, and took possession of the principal avenues, leaving some of their companions to work an opening in the side of the ant-hill with their teeth. Success crowned their enterprise, and by the newly-made breach the remainder of the army entered. Their sojourn was, however, of short duration, for in three or four minutes they returned by the same apertures which gave them entrance, each bearing off in its mouth a larva or a pupa.'

The expeditions generally start in the afternoon, and are from 100 to 2,000 strong.

Polyergus rufescens present a striking lesson of the degrading tendency of slavery, for these ants have become entirely dependent on their slaves. Even their bodily structure has undergone a change: the mandibles have lost their teeth, and have become mere nippers, deadly weapons indeed, but useless except in war. They have lost the greater part of their instincts: their art, that is, the power of building; their domestic habits, for they show no care for their own young, this being done by the slaves; their industry-they take no part in providing the daily supplies; if the colony changes the situation of its nest, the masters are all carried by the slaves on their backs to the new one; nay, they have even lost the habit of feeding. Huber placed thirty of them with some larvæ and pupæ and a supply of honey in a box. At first,' he says,

all

they appeared to pay some little attention to the larvæ; they carried them here and there, but presently replaced them. More than one-half of the Amazons died of hunger in less than two days. They had not even traced out a dwelling, and the few ants still in existence were languid and without strength. I commiserated their condition, and gave them one of their black companions. This individual, unassisted, established order, formed a chamber in the earth, gathered together the larvæ, extricated several young ants that were ready to quit the condition of pupa, and preserved the life of the remaining Amazons.'

This observation has been fully confirmed by other naturalists. However small the prison, however large the quantity of food, these stupid creatures will starve in the midst of plenty rather than feed themselves.

M. Forel was kind enough to send me a nest of Polyergus, and I kept it under observation for more than four years. My specimens of Polyergus certainly never fed themselves, and when the community changed its nest, which they did several times, the mistresses were carried from the one to the other by the slaves. I was even able to observe one of their marauding expeditions, in which, however, the slaves took a part.

I do not doubt that, as Huber tells us, specimens of Polyergus if kept by themselves in a box would soon die of starvation, even if supplied with food. I have, however, kept isolated specimens for three months by giving them a slave for an hour or two a day to clean

and feed them: under these circumstances they remained in perfect health, while, but for the slaves, they would have perished in two or three days. Excepting the slave-making ants, and some of the Myrmecophilous beetles above described, I know no case in nature of an animal having lost the instinct of feeding.

In P. rufescens, the so-called workers, though thus helpless and idle, are numerous, energetic, and in some respects even brilliant. In another slavemaking ant, Strongylognathus, the workers are much less numerous, and so weak that it is an unsolved problem how they contrive to make slaves. In the genus Strongylognathus there are two species, S. huberi and S. testaceus. S. huberi, which was discovered by Forel, very much resembles Polyergus rufescens in habits. They have sabre-like mandibles, like those of Polyergus, and their mode of fighting is similar, but they are much weaker insects; they make slaves of Tetramorium cæspitum, which they carry off as pupæ. In attacking the Tetramoriums they seize them by the head with their jaws, just in the same way as Polyergus, but have not strength enough to pierce them as the latter do. Nevertheless, the Tetramoriums seem much afraid of them.

The other species, Strongylognathus testaceus, is even weaker than S. huberi, and their mode of life is still in many respects an enigma. They also keep the workers of Tetramorium in, so to say, a state of

slavery, but how they procure the slaves is still a mystery. They fight in the same manner as Polyergus; but yet Schenk, Von Hagens, and Forel all agree that they are no match for the Tetramoriums, a courageous species, and one which lives in large communities. On one occasion Forel brought a nest of Tetramorium and put it down very near one of Strongylognathus testaceus with Tetramorium slaves. A battle at once commenced between the two communities. The Strongylognathus rushed boldly to the fight, but, though their side won the day, this was mainly due to the slaves. The Strongylognathus themselves were almost all killed; and though the energy of their attack seemed at first to disconcert their opponents, Forel assures us that they did not succeed in killing even a single Tetramorium. In fact, as Forel graphically observes, Strongylognathus is une triste caricature' of Polyergus, and it seems almost impossible that by themselves they could successfully attack a nest of Tetramorium. Moreover, in Strongylognathus, the workers are comparatively few. Nevertheless, they are always found with the Tetramoriums, and in these mixed nests there are no males or females of Tetramorium, but only those of Strongylognathus. Again, the whole work of the nest is done by the slaves, though Strongylognathus has not, like Polyergus, entirely lost the power of feeding itself.

But if the economy of Strongylognathus is an enigma, that of Anergates is still more mysterious.