Animal Intelligence. George John Romanes
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which had unwarily been allowed to protrude through the meshes of the muslin. They worked and watched, though not, as far as I could see, with any system, till 7.30 in the evening, when they effected an entrance, and immediately attacked the strangers.
Sept. 24.—I repeated the same experiment with the same nest. Again the ants came and sat over the bottle containing the strangers, while no notice was taken of the friends.
The next morning again, when I got up, I found five ants round the bottle containing the strangers, none near the friends. As in the former case, one of the ants had seized a stranger by the leg, and was trying to drag her through the muslin. All day the ants clustered round the bottle, and bit perseveringly, though not systematically, at the muslin. The same thing happened all the following day.
On repeating these experiments with another species (viz., Formica rufescens) the ants took no notice of either bottle, and showed no sign either of affection or hatred. One is almost tempted to surmise that the spirit of these ants is broken by slavery [i.e. by the habit of keeping slaves]. But the experiments on F. fusca seem to show that in these curious insects hatred is a stronger passion than affection.
We must not, however, too readily assent to this general conclusion, that ants as a whole are deficient in the tenderer emotions; for although the case is doubtless so with the species which Sir John examined, it appears to be certainly otherwise with other species, as we shall presently see. But first it may be well to point out that even the hard-hearted species with which Sir John had to do seem not altogether devoid of sympathy with sick or mutilated friends, although they appear to be so towards healthy friends in distress. Thus the care shown to intoxicated friends seems to indicate, if not, as already observed, a dim sense of sympathy, at least an instinct to preserve the life of an ailing citizen for the future benefit of the community. Sir John also quotes some observations of Latreille showing that ants display sympathy with mutilated companions; and, lastly, mentions an instance which he has himself observed of the same thing. A specimen of F. fusca congenitally destitute of antennæ was attacked and injured by an ant of another species. When separated by Sir John, another ant of her own species came by. 'She examined the poor sufferer carefully, then picked her up tenderly, and carried her away into the nest. It would have been difficult for any one who witnessed this scene to have denied to this ant the possession of humane feelings.' Moggridge is also of opinion that the habit of throwing sick and apparently dead ants into the water, is 'in part to be rid of them, and partly, perhaps, with a view to effecting a possible cure; for I have seen one ant carry another down the twig which formed their path to the surface of the water, and, after dipping it in for a minute, carry it laboriously up again, and lay it in the sun to dry and recover.'
But that some species of ants display marked signs of what we may call sympathy even towards healthy companions in distress, is proved by the following observation of Mr. Belt. He writes:[21]—
One day, watching a small column of these ants (i.e. Eciton humata), I placed a little stone on one of them to secure it. The next that approached, as soon as it discovered its situation, ran backwards in an agitated manner, and soon communicated the intelligence to the others. They rushed to the rescue; some bit at the stone and tried to move it, others seized the prisoner by the legs and tugged with such force that I thought the legs would be pulled off, but they persevered until they got the captive free. I next covered one up with a piece of clay, leaving only the ends of its antennæ projecting. It was soon discovered by its fellows, which set to work immediately, and by biting off pieces of the clay soon liberated it. Another time I found a very few of them passing along at intervals. I confined one of these under a piece of clay at a little distance from the line, with his head projecting. Several ants passed it, but at last one discovered it and tried to pull it out, but could not. It immediately set off at a great rate, and I thought it had deserted its comrade, but it had only gone for assistance, for in a short time about a dozen ants came hurrying up, evidently fully informed of the circumstances of the case, for they made directly for their imprisoned comrade and soon set him free. I do not see how this action could be instinctive. It was sympathetic help, such as man only among the higher mammalia shows. The excitement and ardour with which they carried on their unflagging exertions for the rescue of their comrade could not have been greater if they had been human beings.
This observation seems unequivocal as proving fellow-feeling and sympathy, so far as we can trace any analogy between the emotions of the higher animals and those of insects. That insects with such highly organised social habits, and depending so greatly on the principles of co-operation, should manifest emotions or instincts of an incipiently altruistic character, is no more than we should antecedently expect on the general principle of survival of the fittest. Our only surprise should be that these emotions, or instincts, should appear to be so feebly developed in some species of ants, and, as we shall subsequently see, also of bees. But it may be worth while in this connection to point out that the valuable observation of Mr. Belt above quoted refers to the species of ant which, as we shall subsequently find, presents the most highly organised instincts of co-operation that are to be met with among ants, and therefore the greatest dependence of the welfare of the individual on that of the community. And the same remark is applicable to our native species, F. sanguinea, which the Rev. W. W. F. White has repeatedly seen rescuing buried companions very much in the manner described by Mr. Belt; and he does not appear to be acquainted with Mr. Belt's observations. He figures one case in which he saw three ants co-operating to dig out a buried comrade.[22]
Powers of Communication.
Huber, Kirby and Spence, Dugardin, Burmeister, Franklin, and other observers have all expressed themselves as more or less strongly of the opinion that members of the same community of ants, and other social Hymenoptera, are able to communicate information to one another by some system of language or signs. The facts, however, on which their opinion rests have not been stated with that degree of caution and detail which the acceptance of the conclusion requires. Thus, Kirby and Spence give only one instance of supposed communication between ants,[23] and even this one is inconclusive, as the facts described admit of being explained by supposing that the ants simply tracked one another by scent; while Huber merely deals in general statements as to 'contact of antennæ,' without narrating any particulars of his observations. Therefore, until within the last few years there was really no sufficient evidence to sustain the general opinion that ants are able to communicate with one another; but the observations which I shall now detail must be regarded as fully substantiating that general opinion by facts as abundant and conclusive as the most critical among us can desire. I shall first narrate in his own words the more important of Sir John Lubbock's experiments in this connection:—
I took three tapes, each about 2 feet 6 inches long, and arranged them parallel to one another and about 6 inches apart. An end of each I attached to one of the nests (F. niger), and at the other end I placed a glass. In the glass at the end of one tape I placed a considerable number (300 to 600) of larvæ. In the second I put two or three larvæ only, in the third none at all. The object of the last was to see whether many ants would come to the glasses under such circumstances by mere accident, and I may at once say that scarcely any did so. I then took two ants, and placed one of them to the glass with many larvæ, the other to that with two or three. Each of them took a larva and carried it to the nest, returning for another, and so on. After each journey I put another larva in the glass with only two or three larvæ, to replace that which had been removed. Now, if several ants came under the above circumstances as a mere matter of accident, or accompanying one another by chance, or if they simply saw the larvæ which were being brought, and consequently concluded that they might themselves find a larva in the same place, then the numbers going to the two glasses ought to be approximately equal. In each case the number of journeys made by the ants would be nearly the same; consequently, if it was a matter of scent, the two glasses would be in the same position. It would be impossible for an ant, seeing another in the act of bringing a larva, to judge for itself whether there were few or many left behind. On the other hand, if the strangers were brought,