In Switzerland the slaves and masters work together, making and bringing materials for the nest: both, but chiefly the slaves, tend and milk as it may be called, their aphides; and thus both collect food for the community.

In England the masters alone usually leave the nest to collect building materials and food for themselves, their slaves and larvae.

So that the masters in this country receive much less service from their slaves than they do in Switzerland.

By what steps the instinct of F.

sanguinea originated I will not pretend to conjecture.