THE SAXGL'IXARY ANTS. 4 6 9 



species, and to this extent my views coincide with those of Wasmann 

 and Santschi. 



Great difficulty was formerly experienced in accounting for the 

 various dulotic instincts, because these were supposed to be the exclu- 

 sive property of the sterile workers. On this assumption they could 

 be transmitted only through the queen and she was supposed not to 

 manifest them. The discovery in the queen of a type of behavior 

 essentially like that of the workers solves this problem, for these 

 instincts are seen to be primarily important in the establishment of the 

 colony. They are naturally inherited by the workers, but in this caste 

 they have been modified and intensified by fusion with the foraging 

 instincts. Thus instincts which in the reproductive caste are useful 

 in establishing the colony are useful in the sterile caste in procuring 

 food and incidentally, perhaps, in adding to the working personnel of 

 the colony. The differences in the display of the instinct by the two 

 castes is due to the fact that the workers make their forays in concert 

 and on populous colonies of the slave species, which the female could 

 probably not enter. The discriminative character of dulosis, that is, its 

 concentration on particular slave species, may be readily explained by 

 the fact that both worker and queen sanguined have been reared by the 

 slave-workers, or at any rate have become familiar with them in the 

 parental nest. What is more natural, therefore, than that both san- 

 gulnea queens and workers should seek out colonies of the familiar 

 species, the queens for the purpose of nidification, the workers for the 

 purpose of obtaining food? If we adopt Wasmann's view that the 

 young of the slave species are pillaged for the purpose of being reared 

 instead of eaten, we may suppose that the pure colonies of these species 

 in the vicinity of the sanguined nests appear to these ants as so many 

 detached and refractory portions of their own colony and therefore to 

 be brought together in the one nest. I have already given my reasons 

 for dissenting from Wasmann's view, although I admit that the san- 

 (juinea workers of the same or different colonies may inherit in very 

 different intensities their mother's instinct to pillage larvae and cocoons 

 for the sake of rearing them, and that the number of slaves in a colony 

 may represent the degree to which this instinct on the part of the work- 

 ers preponderates over that of hunger. Hunger and affection are such 

 closely linked emotions in all animals that we cannot doubt that queens 

 and workers alike possess them. They are, moreover, displayed by all 

 ants in their tendency to eat their own larvae and pupae. It is certain, 

 however, that a rational explanation of slavery can be formed only by 

 recognizing it as a form of parasitism in which the slaves are the host. 



