ate, it is the slaves which determine the migration, and actually carry
their masters in their jaws. So utterly helpless are the masters, that when
Huber shut up thirty of them without a slave, but with plenty of the food
which they like best, and with their larvae and pupae to stimulate them to
work, they did nothing; they could not even feed themselves, and many
perished of hunger. Huber then introduced a single slave (F. fusca), and
she instantly set to work, fed and saved the survivors; made some cells and
tended the larvae, and put all to rights. What can be more extraordinary
than these well-ascertained facts? If we had not known of any other
slave-making ant, it would have been hopeless to have speculated how so
wonderful an instinct could have been perfected.

Another species, Formica sanguinea, was likewise first discovered by P.
Huber to be a slave-making ant. This species is found in the southern parts
of England, and its habits have been attended to by Mr. F. Smith, of {220}
the British Museum, to whom I am much indebted for information on this and
other subjects. Although fully trusting to the statements of Huber and Mr.
Smith, I tried to approach the subject in a sceptical frame of mind, as any
one may well be excused for doubting the truth of so extraordinary and
odious an instinct as that of making slaves. Hence I will give the
observations which I have myself made, in some little detail. I opened
fourteen nests of F. sanguinea, and found a few slaves in all. Males and
fertile females of the slave-species (F. fusca) are found only in their own
proper communities, and have never been observed in the nests of F.
sanguinea. The slaves are black and not above half the size of their red
masters, so that the contrast in their appearance is very great. When the
nest is slightly disturbed, the slaves occasionally come out, and like
their masters are much agitated and defend the nest: when the nest is much
disturbed and the larvae and pupae are exposed, the slaves work energetically
with their masters in carrying them away to a place of safety. Hence, it is
clear, that the slaves feel quite at home. During the months of June and
July, on three successive years, I have watched for many hours several
nests in Surrey and Sussex, and never saw a slave either leave or enter a
nest. As, during these months, the slaves are very few in number, I thought
that they might behave differently when more numerous; but Mr. Smith
i