lOO Bulletin American Musetifn of Natural History. [Vol. XXII, 



female ants sometimes behave like the workers in caring for the young, 

 feeding other members of the colony, etc. Because female ants are 

 slow to manifest certain reactions, or fail to do so entirely, except 

 under the stress of unusual stimuli, we should not say that the ca- 

 pacity is absent, any more than we admit the absence of an hereditary 

 character which remains latent during one or more generations. To 

 use the language of the neovitalist, the entelechy of the worker ant is 

 involved in that of the female. While the instincts of the worker ants 

 are very important in all that relates to the inheritance and mainte- 

 nance of the colony — its Betriebsfunktionen, to use a German word — the 

 instincts of the female are of supreme significance in all that relates 

 to the reproduction of the species; to the ontogenetic and hence 

 also to the phylogenetic development of colonies. This seems to have 

 been overlooked in all previous attempts to explain social parasitism 

 and dulosis. Wasmann, for example, continually stresses the dulotic 

 activities of the workers and the impossibility of explaining them 

 except as manifestations of an inordinate fondness for rearing the 

 larvae and pupae of an alien ant, on the part of an enterprising and 

 pugnacious species which would seem to be well able to hold its own 

 in the struggle for existence without resorting to any such methods 

 for the enlargement of its colonies. 



There are obviously some further bearings of these general con- 

 siderations on the subject of dulosis. It is possible, in the light of the 

 experiments on rubicunda, to regard the slave-making instincts of 

 the workers of this species as at most only exaggerations of similar in- 

 stincts in the female. In the former, however, they are more suffused 

 with the instinct to forage in files. As Forel and I have shown, a 

 large portion of the larvae and pupae kidnapped by sanguinea workers 

 must be eaten, although some of them are reared in obedience to the 

 threptic instincts, which the workers, of course, share with the queens. 

 It is not even necessary, however, to regard these instincts as unusually 

 developed in the workers of the slave-making species. In the rubi- 

 cunda queen, they naturally predominate, although in one experiment 

 a single small subsericea larva was eaten. Unfortunately I failed to 

 give much attention to the larvae used in my experiments, which should 

 therefore be repeated with a view to ascertaining whether the female 

 sanguinea does not satisfy her hunger occasionally with .some of the 

 fusca larvae if she is required to wait too long for the hatching of the 

 pupae. 



As I have already intimated, there seems to be no way to derive 

 the dulotic instincts from a condition of temporary social parasitism 



