560 Saw-flies, Gall-flies, Ichneumons, 
vorum) not only in the same genus but among closely allied forms. This 
jact also suggests that the instincts 0) the same species may be so generalized 
as to enable it to junction like man , either as a slave or master , according to 
the circumstances 
And this leads us to consider briefly that extremest form of consociation 
between two ant species, namely, the so-called dulosis, the living together of 
slave-makers and slaves. To put summarily the result of various careful 
studies of dulotic communities made by both European and American 
observers, it may be said that this condition has grown out of the general 
instinct that most ants show, to obtain when and where possible the larvae 
and pupae of other ant species for food. From a raid on a neighboring com¬ 
munity and the immediate devouring of as many larvae and pupae as possible 
to a similar attack and feast plus the bringing home of a supply of this choice 
food to be stored for eating through the next few days is a natural, and as, 
exemplified by numerous observed cases, an actual s ep. Then if the booty 
be large in amount, it is inevitable that some of the pupae shall transform 
in the new nest. Now, are these newly issued workers to be at once 
attacked and eaten? This depends on whether the proper stimulus is. 
present or not. As practically certainly determined by numerous observa¬ 
tions and experiments the stimulus for attack and war among ants (as 
well as bees) is odor; recognition of nest mate and perception of intruder 
or foreigner depends probably solely on the sense of smell, and the 
stimulation of this sense has come during the evolution of the instincts, 
of ants to be a stimulus to direct reflexive action; the odor of the home 
community determines friendly behavior, the odor of any other community 
gives direct rise to attack. Now, this odor has several component ele¬ 
ments; one, for example, inherited (by the inheritance of a characteristic 
metabolism) from the queen, so that descendants of a common mother, or 
of sister-mothers (common grand-maternal inheritance), have an odor with 
something in common; another element and a strong one is, however, the 
nest odor compounded of all the individual odors in a community and gradu¬ 
ally taken on by each hatching young. If the young be removed from one 
community and be hatched in another they seem to take on the odor 
of the second community. And so the living booty brought back by the 
raiders, issuing in the new nest, becomes endowed with the odor of the new 
community and is unmolested. But the instinct of the hatched workers 
is to work; and so work they do. If their work is of advantage to the raider 
community, natural selection will do the rest. In the beginning there 
were no slave-makers; raiders there were which raided other nests, not for 
slaves, but for food. But bringing home extra supplies of this food, which 
hatched and lived and worked in the new nest, evolution from food to slaves, 
and from raiders to slave-holders has naturally taken place. Now such 
