were watched continuously until 4 P.M., but were not attacked, nor even threatened. The following morning one of them was quite well, the other one we could not distinguish; she had probably been cleaned. If she had been killed, we must have found her dead body. I then at 10 A.M. put in two more. At 10.30 one of them was attacked for a moment, but only for a moment. With this exception neither of them was attacked until 2 o'clock, when one of them was again seized and dragged about for a minute or two, but then released again. We continued watching them till half-past 4, when they seemed quite at home amongst the others. On the other hand a stranger, put in as a test at 12, was at once attacked. It was curious, however, that although she was undoubtedly attacked, yet at the very same time another ant began to clean her.

The next morning we found one ant, and only one, in the box outside the nest; and this turned out to be the stranger of yesterday. She had been almost cleaned; but there were one or two small particles of paint still remaining, so that there could be no doubt of her identity.

The next day, November 27, I put in three more of the ants derived from these pupa at 10 A.M. At 10.30 they were all right, running about amongst the others. At 11 o'clock the same was the case; but whilst I was looking again shortly afterwards, one of them was seized by an antenna and dragged a little

way, but released again in less than a minute. Shortly afterwards one of the others was also seized, but let go again almost immediately. At one o'clock they were all right, and also at two. They had, however, in the meantime been more than once threatened, and even momentarily seized, though they were never dragged about as strangers would have been. At three o'clock I found one of them dead; but I think I must have accidentally injured her, and I do not believe that she was killed by the other ants, though I cannot speak quite positively about it. The other two were quite at home, and had been partly cleaned. At six one of them was running about comfortably amongst the rest; the other I could not distinguish; but certainly no ant was being attacked.

November 28.-I put in the last two ants from the above-mentioned batch of pupæ at noon. Like the preceding, these ants were occasionally threatened, and even sometimes attacked for a moment or two; but the other ants soon seemed to find out their mistake, and on the whole they were certainly treated as friends, the attacks never lasting more than a few moments. One of them was watched at intervals of half an hour until 5 P.M.; the other we could not distinguish after 3 P.M., the paint having been licked off; but we should certainly have observed it had she been attacked.

On the whole, then, all the thirty-two ants belonging to Formica fusca and Lasius niger, removed from

L

their nest as pupa, attended by friends, and restored to their own nest, were amicably received.

What is still more remarkable, of twenty-two ants belonging to F. fusca, removed as pupa, attended by strangers, and returned to their own nest, twenty were amicably received. As regards one I am doubtful; the last was crippled in coming out of the pupa-case; and to this perhaps her unfriendly reception may have been due.

Of the same number of Lasius niger developed in the same manner from pupæ tended by strangers belonging to the same species, and then returned into their own nest, nineteen were amicably received, three were attacked, and about two I feel doubtful.

On the other hand, fifteen specimens belonging to the same two species, removed as pupæ, tended by strangers belonging to the same species, and then put into the strangers' nest, were all attacked.

The results may be tabulated as follows:-
:-

of temperament in different nests. The specimens of F. fusca experimented with in August and September last were taken principally from two nests, numbered respectively 36 and 60. Now, while nest 36, in most

1 I do not feel sure about three of these.

cases, amicably received ants bred from its own pupa but tended by ants from 60, it showed itself fiercely hostile to ants from pupa born in nest 60, even when these had been tended by ants from nest 36. Nest 60, again, behaved in a similar manner; amicably receiving, as a general rule, its own young, even when tended by ants from 36; and refusing to receive ants born in nest 36, even when tended by specimens from nest 60.

These experiments seem to indicate that ants of the same nest do not recognise one another by any password. On the other hand, they seem to show that if ants are removed from a nest in the pupa-state, tended by strangers, and then restored, some at least of their relatives are puzzled, and for a time doubt their claim to consanguinity. I say some, because while strangers under the circumstances would have been immediately attacked, these ants were in every case amicably received by the majority of the colony, and it was sometimes several hours before they came across one who did not recognise them.

In all these experiments, however, the ants were taken from the nest as pupa, and though I did not think the fact that they had passed their larval existence in the nest could affect the problem, still it might do so. I determined therefore to separate a nest before the young were born, or even the eggs laid, and then ascertain the result. Accordingly I took one of my nests of F. fusca, which I began watching on Sept. 13, 1878, and which contained two queens, and on February 8,

1879, divided it into halves, which I will call A and B, so that there were approximately the same number of ants with a queen in each division. At this season, of course, the nest contained neither young nor even eggs. During April both queens began to lay eggs. On July 20 I took a number of pupæ from each division and placed each lot in a separate glass, with two ants from the same division. On August 30 I took four ants from the pupæ bred in B, and one from those in A (which were not quite so forward), and after marking them as usual with paint, put the B ants into nest A, and the A ant into nest B. They were received amicably and soon cleaned. Two, indeed, were once attacked for a few moments, but soon released. the other hand, I put two strangers into nest A, but they were at once driven out. For facility of observation I placed each nest in a closed box. On the 31st I carefully examined the nests and also the boxes in which I placed them. I could only distinguish one of the marked ants, but there were no dead ants either in the nests or boxes.

On

I carefully examined the box in the same way for several successive mornings, but there was no dead ant. If there had been I must have found the body, and I am sure, therefore, that these ants were not attacked.

Again, on August 31 I put two more of the ants which had emerged from the pupa taken out of nest B, and nursed by ants from that nest, into nest A at