13 



IV. Differs from II. (a) only by the fact that, the species 

 of the ahen queen having no worker caste, the colony only lasts 

 for the lifetime of the host workers. 



We do not propose to enter here into a discussion as to whether 

 the slave-making habit originated in robbery or parasitism, as 

 such a controversy is not germane to the subject of this paper, 

 which deals only with facts, but we feel bound to refer to 

 Darwin's views on the origin of slavery. In a much-quoted 

 passage he writes : 



" By what steps the instinct of F. sangiiinca originated I will 

 not pretend to conjecture. But as ants which are not slave- 

 makers will, as I have seen, carry off the pupie of other species, 

 if scattered near their nests, it is possible that such pupae origin- 

 ally stored as food might become developed ; and the foreign 

 ants thus unintentionally reared would then follow their proper 

 instincts, and do what work they could. If their presence 

 proved useful to the species which had seized them — if it were 

 more advantageous to this species to capture workers than to 

 procreate them — the habit of collecting pupie, originally for 

 food, might by natural selection be strengthened and rendered 

 permanent for the very diñerent purpose of raising slaves. 

 When the instinct was once acquired, if carried out to a much 

 less extent even than in our British F. sanguinea, which, as we 

 have seen, is less aided by its slaves than the same species in 

 Switzerland, natural selection might increase and modify the 

 instinct — always supposing each modification to be of use to 

 the species — until an ant was formed as abjectly dependent on 

 its slaves as is the Formica rufcscens." 



This supposition has been much criticised, but it is by no 

 means so inaccurate as has been suggested. 



As we shall see later, other species of ants besides the slave- 

 makers do raid strange nests and steal the pup;e for food, and 

 will occasionally actually bring them to maturity. As to the 

 origin of slavery, if Darwin had known, as we know to-day, 

 that the queen sanguinea does not herself found her colony, but 

 from the very first steals the fusca pupae, one of his greatest 

 difficulties would have been removed, viz. the attempt to under- 

 stand how it is that the workers, which do not normally breed, 

 inherit the slave-making instinct. 



