The genus Anergates was discovered by Schenk,' who found a small community consisting of males, females and workers, which he naturally supposed to belong to one species. Mayr, however, pointed out' that the workers were in fact workers of Tetramorium caspitum; and it would appear that while in Strongylognathus the workers are comparatively few, Anergates differs from all other ants in having no workers at all. The males and females live with Tetramorium caspitum, and are in several respects very peculiar,— for instance, the male is wingless. One might consider it rather a case of parasitism than of slavery, but the difficulty is that in these mixed nests there are no males, females, or young of Tetramorium. As to this all observers are agreed. It seems quite clear that Anergates cannot procure its slaves, if such they are, by marauding expeditions like those of Polyergus; in the first place, because the Anergates are too few, and secondly, because they are too weak. The whole question is rendered still more difficult by the fact that neither Von Hagens3 nor Forel ever found either larvæ or pupæ of Tetramorium in the mixed nests. The community consisted of males and females of Anergates, accompanied and tended by workers of Tetramorium caspitum. The Anergates are absolutely dependent I'Die Nassauischen Ameisen-Species,' Stettin Ent. Zeit. 1853,

p. 186.

2 Europ. Formicidæ, p. 56.

• Vorh. des Natur. Vereines der Preuss. Rheinlande und West phalens 1867, p. 53. See also V. Hagens. Berl. Ent. Zeit. 1867, p. 102

upon their slaves, and cannot even feed themselves. The whole problem is, therefore, most puzzling and interesting.1

As regards Strongylognathus, Von Hagens made two suggestions, the first being that this insect is really a monstrous form of Tetramorium. This, however, cannot at any rate be the case with Anergates. On the whole, then, he inclines to think that perhaps the nests containing Strongylognathus or Anergates are only parts of a community, and that the young of the Tetramoriums are in another nest of the same community. This would account for the absence of the young of the Tetramoriums, but would not remove all the difficulties. It is in other respects not consistent with what we know of the habits of ants, and on the whole I agree with Forel in thinking the suggestion untenable.

The difficulty of accounting for the numbers of Tetramoriums, coupled with the absence of young, was indeed almost insuperable as long as the workers were supposed to live only for one year. My observations, however, which show that even in captivity a nest may continue for five years, place the question in a different position, and give us, I think, a clue.

On the whole, I would venture to suggest that the male and female Anergates make their way into a nest

On the contrary, in Tomognathus sublævis, a Finland species which lives in the nests of Leptothorax muscorum and L. acervorum, the workers only are known. The male, like that of Anergates, is wingless.

of Tetramorium, and in some manner contrive to assassinate their queen. I have shown that a nest of ants may continue, even in captivity, for five years, without a queen. If, therefore, the female of Anergates could by violence or poison destroy the queen of the Tetramoriums, we should in the following year have a community composed of the two Anergates, their young, and workers of Tetramorium, in the manner described by Van Hagens and Forel. This would naturally not have suggested itself to them, because if the life of an ant had, as was formerly supposed, been confined to a single season, it would of course have been out of the question; but as we now know that the life of ants is so much more prolonged than had been supposed, it is at least not an impossibility.

It is conceivable that the Tetramoriums may have gradually become harder and stronger; the marauding expeditions would then be less fruitful and more dangerous, and might become less and less frequent. If, then, we suppose that the females found it possible to establish themselves in nests of Tetramorium, the present state of things would almost inevitably be, by degrees, established. Thus we may explain the reinarkable condition of Strongylognathus, armed with weapons which it is too weak to use, and endowed with instincts which it cannot exercise.

At any rate, these four genera offer us every gradation from lawless violence to contemptible parasitism. Formica sanguinea, which may be assumed to have

comparatively recently taken to slave-making, has not as yet been materially affected.

Polyergus, on the contrary, already illustrates the lowering tendency of slavery. They have lost their knowledge of art, their natural affection for their young, and even their instinct of feeding! They are, however, bold and powerful marauders.

In Strongylognathus, the enervating influence of slavery has gone further, and told even on the bodily strength. They are no longer able to capture their slaves in fair and open warfare. Still they retain a semblance of authority, and, when roused, will fight bravely, though in vain.

In Anergates, finally, we come to the last scene of this sad history. We may safely conclude that in distant times their ancestors lived, as so many ants do now, partly by hunting, partly on honey; that by degrees they became bold marauders, and gradually took to keeping slaves; that for a time they maintained their strength and agility, though losing by degrees their real independence, their arts, and even many of their instincts; that gradually even their bodily force dwindled away under the enervating influence to which they had subjected themselves, until they sank to their present degraded condition-weak in body and mind, few in numbers, and apparently nearly extinct, the miserable representatives of far superior ancestors, maintaining a precarious existence as contemptible parasites of their former slaves.

M. Lespès has given a short but interesting account of some experiments made by him on the relations existing between ants and their domestic animals, from which it might be inferred that even within the limits of a single species some communities are more advanced than others. He states that specimens of the curious blind beetle Claviger, which always occurs with ants, when transferred from a nest of Lasius niger to another which kept none of these domestic beetles, were invariably attacked and eaten. From this he infers that the intelligence necessary to keep Clavigers is not coextensive with the species, but belongs only to certain communities and races, which, so to say, are more advanced in civilisation than the rest of the species.

With reference to the statements of Lespès, I have more than once transferred specimens of Platyarthrus from one nest to another, and always found them received amicably. I even placed specimens from a nest of Lasius flavus in one of Formica fusca with the same result. I brought from the South of France some specimens of a different species, as yet undescribed, and put them in a nest of Formica fusca, where they lived for some time, and brought up more than one brood of young. These creatures, however, occur in most ants' nests, while Clavigers are only found in some.

But whether there are differences in advancement within the limits of the same species or not, there are