that all the ants of the same community recognize one another as friends, while an ant introduced from another nest, even though it be an ant of the same species, is known at once to be a foreigner, and is usually maltreated or put to death. Huber found that, when he removed an ant from a nest and kept it away from its companions for a period of four months, it was still recognized as a friend, and caressed by its previous fellow-citizens after the manner in which ants show friendship, viz., by stroking antennæ. Sir John Lubbock, after repeating and fully confirming these observations, extended them as follows:
He first tried prolonging the period of separation beyond four months, and found that it might be made more than three times as long without the ants forgetting their absent friend. Thinking that this fact could only be explained, either by all the ants knowing each other's personal appearance, or by their all having a distinctive smell peculiar to each nest, or by their all having a sign, like a pass-word, differing in different nests. Sir John tried separating some ants from a nest while still in the condition of larvæ, and, when they emerged as perfect insects, transferring them back to the nest from which they had been taken as larvæ. Of course, in this case the ants in the nest could never have seen those which had been removed, for a larval ant is as unlike the mature insect as a caterpillar is unlike a butterfly; neither can it be supposed that the larvæ, thus kept away from the nest, should retain, when hatched out as perfect insects, any smell belonging to their parent nest; nor, lastly, is it reasonable to imagine that the animals, while still in the condition of larval grubs, can have been taught any gesture or sign used as a pass-word by the matured animals. Yet, although all these possible hypotheses seem to be thus fully excluded by the conditions of the experiment, the result showed unequivocally that the ants all recognized their transformed larvæ as native-born members of their community.
Next, therefore. Sir John Lubbock tried dividing a nest into two parts before the queen ants had become pregnant. Seven months after the division the queens laid their eggs, and five months later these eggs had developed into perfect insects. He then transferred some of these young ants from the division of the nest in which they had been born to the division in which they had never been, even in the state of the egg. Yet these ants also were received as friends, in marked contrast to the reception accorded to ants from any other nest. It therefore seems to be blood-relationship that ants are able, in some way that is as yet wholly inexplicable, to recognize. It ought, however, to be remembered in this connection that, in an experiment made by Forel on slave-making ants, it was proved that they almost instantaneously recognized their own slaves from other slaves of the same species—and this after their slaves had been kept away from the nest for a period of four months.
