Hence, I will give the observations which I 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 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 together with their masters in carrying them away to a place of safety.