10 A.M. At 10.30 A.M. they were quite comfortable amongst the others. At 11 A.M. I looked again and they seemed quite at home, as also at 11.30 A.M., after which for some time I looked every hour, and they were never attacked. The next morning I found them peaceably among the other ants.

On September 15 I put three of the ants which had emerged from the pupae taken out of nest A, and nursed by ants from that nest, and put them into nest B at 1.30 P.M. They seemed to make themselves quite at home. I looked again at 2.30 P.M., with the same result. At 3.30 P.M. I could only find two, the third having no doubt been cleaned, but no ant was being attacked. At 5.30 P.M. they were no longer distinguishable, but if any one was being attacked we must have seen it. The next morning they all seemed quite peaceful, and there was no dead ant in the box. I looked again on the 17th and 19th, but could not distinguish them. As, however, there was no dead ant, they certainly had not been killed. I then put in a stranger; she was soon attacked and driven out of the nest-showing that, as usual, they would not tolerate an ant whom they did not recognise as in some way belonging to the community.

Again, on April 10, 1881, I divided a two-queened nest of Formica fusca, leaving a queen in each half. At that time no eggs had yet been laid, and of course there were no larvæ or pupæ. In due course both queens laid eggs, and young ants were brought up in

150 RECOGNITION NOT INDIVIDUAL OR PERSONAL,

each half of the nest. I will call the two halves as before A and B.

On August 15, at 9 A.M., I put three of the young ants from A into B, and three from B into A. At 9.30 A.M. none were attacked, 10 A.M. ditto, 10.30 a.m. ditto. One was being cleaned; 12 A.M. ditto, 2 P.M. ditto. In fact, they seemed quite at home with the other ants. The next morning I was unable to recognise them, the paint having been entirely removed. The ants were all peaceably together in the nest, and there were no dead ones either in the nest or in the outer box. It is evident, therefore, that they had been treated as friends.

August 17.-I put in three more from B into A at noon. At 12.30 P.M. they were with the other ants; at 1 P.M., ditto, at 2 P.M. ditto, at 3 P.M. ditto, at 5 P.M. ditto. The following morning I was still able to recognise them, though most of the paint had been removed. They also were evidently treated as part of the community.

September 19.-Put in three more from A into B at 8.30 A.M. I looked at them at intervals of half an hour, but none of them were attacked. Next morning there was no ant outside the nest, nor had any been killed.

October 10.-Put in three more at 7 A.M., and looked at intervals of an hour. They were not attacked, and evidently felt themselves among friends. The next morning I was still able to recognise two.

There was no dead ant either in the nest or the outer box.

Lastly, on October 15, I put in four more at 7 A.M., and watched them all day at short intervals. They exhibited no sign of fear, and were never attacked. In fact, they made themselves quite at home, and were evidently, like the preceding, recognised as friends. For the sake of comparison at noon I again put in a stranger. Her behaviour was in marked contrast. The preceding ants seemed quite at home, walked about peaceably among the other ants, and made no attempt to leave the nest. The stranger, on the contrary, ran uneasily about, started away from any ant she met, and made every effort to get out of the nest. After she had three times escaped from the nest, I put her back with her own friends.

Thus, then, when a nest of Formica fusca was divided early in spring, and when there were no young, the ants produced in each half were in twenty-eight cases all received as friends. In no case was there the slightest trace of enmity.

These observations seem to me conclusive as far as they go, and they are very surprising. In the previous experiments, though the results were similar, still the ants experimented with had been brought up in the nest, and were only removed after they had become pupæ. It might therefore be argued that the ants having nursed them as larvæ, recognized them when they came to maturity; and though this would cer

tainly be in the highest degree improbable, it could not be said to be impossible. In the present case, however, the old ants had absolutely never seen the young ones until the moment when, some days after arriving at maturity, they were introduced into the nest; and yet in twenty-one cases they were undoubtedly recognised as belonging to the community.

It seems to me, therefore, to be established by these experiments that the recognition of ants is not personal or individual; that their harmony is not due to the fact that each ant is individually acquainted with every other member of the community.

At the same time, the fact that they recognise their friends even when intoxicated, and that they know the young born in their own nest even when they have been brought out of the chrysalis by strangers, seems to indicate that the recognition is not effected by means of any sign or password.

153

CHAPTER VII.

POWER OF COMMUNICATION.

THE Social Hymenoptera, according to Messrs. Kirby and Spence,1 ́have the means of communicating to each other information of various occurrences, and use a kind of language which is mutually understood, and is not confined merely to giving intelligence of the approach or absence of danger; it is also co-extensive with all their other occasions for communicating their ideas to each other.'

Huber assures us as regards Ants 2 that he has 'frequently seen the antennæ used on the field of battle to intimate approaching danger, and to ascertain their own party when mingled with the enemy; they are also employed in the interior of the ant-hill to apprise their companions of the presence of the sun, so favourable to the development of the larvæ, in their excursions and emigrating to indicate their route, in their recruitings to determine the time of departure,' &c. Elsewhere also he says 3that should an Ant fall in with any of her associates from the nest they put her in the right way by the contact of their antennæ.' 2 Loc. cit. p. 206.

1 Introduction to Entomology, ii. p. 50. Loc. cit. p. 157.