316 WILLIAM MORTON WHEELER 
allied species, snatches up the worker brood and kills any of the 
workers or queens that endeavor to dispute her possessions. The 
ants hatch with a sense of affiliation with their foster mother and 
proceed to rear her eggs and larvee as soon as they appear. Here, 
too, the colony isformed by amixture of two species, but the work- 
ers produced by the intrusive queen inherit her predatory instincts 
and therefore become slave-makers. They keep on kidnapping 
worker larve and pupe from the nests of the alien species, carry 
them home, and eat some of them but permit many to mature, so 
that the mixed character of the colony is maintained. This, how- 
ever, is not invariably the case, for old and vigorous sanguinea 
colonies may cease to make slave-raids and the slaves may die off 
and leave a pure colony of the predatory species. The advantages 
of this method of colony formation are obvious, for the colonial 
soma, being composed of two species, grows more rapidly and is 
much more efficient as a nutritive and protective support to the 
colonial germ-plasm, which is restricted to the predatory species. 
3. The colony-founding queen of the amazon ants of the genus 
Polyergus resorts to a modification of the method adopted by 
sanguinea, as has been shown by Emery’s recent observations. 
She enters the colony of an alien species, perforates its queen’s 
head with her sickle-shaped mandibles and permits herself to be 
adopted by the workers. She pays no attention to the brood but 
begins to lay eggs, the larvee from which are carefully reared by 
the workers. The Polyergus offspring inherit the pugnacity of 
their mother, but, like the sanguinea workers, have the ability 
to kidnap the brood of other ants. They are, in fact, slave-makers 
of a very deft and ferocious type. Like their mother, however, 
they are unable to excavate the nest, to care for their own young 
or to take food except from the mouths of the workers that hatch 
from the kidnapped larve and pupe. The mixture of the two 
species is therefore obligatory, and the slave personnel, which 
represents the nutritive and nest-building portions of the colonial 
soma, has to be maintained throughout the life of the colony. 
4. Certain feeble queen ants belonging to a few aberrant 
genera (Anergates, Wheeleriella) invade populous nests of an alien 
species and are adopted in the place of their queens, which are 
