868 THE ORIGIN OF SPECIES 



Oue evening I visited another community of F. 

 Banguiuea, and found a number of these ants returning 

 home and entering their nests, carrying the dead bodies 

 of F. fusca (showing that it was not a migration) and 

 numerous pupee. I traced a long file of ants burdened 

 with booty, for about forty yards back, to a very thick 

 clump of heath, whence I saw the last individual of F. 

 sanguinea emerge, carrying a pupa; but I was not able 

 to find the desolated nest in the thick heath. The nest, 

 however, must have been close at hand, for two or three 

 individuals of F. fusca were rushing about in the greatest 

 agitation, and one was perched motionless with its own 

 pupa in its mouth on the top of a spray of heath, an 

 image of despair over its ravaged home. 



Such are the facts, though they did not need confir- 

 mation by me, in regard to the wonderful instinct of 

 making slaves. Let it be observed what a contrast the 

 instinctive habits of F. sanguinea present with those of 

 the continental F. rufescens. The latter does not build 

 its own nest, does not determine its own migrations, does 

 not collect food for itself or its young, and cannot even 

 feed itself: it is absolutely dependent on its numerous 

 slaves. Formica sanguinea, on the other hand, possesses 

 much fewer slaves, and in the early part of the summer 

 extremely few: the masters determine when and where a 

 new nest shall be formed, and when they migrate, the 

 masters carry the slaves. Both in Switzerland and Eng- 

 land the slaves seem to have the exclusive care of the 

 larvae, and the masters alone go on slave-making expedi- 

 tions. In Switzerland the slaves and masters work to- 

 gether, making and bringing materials for the nest; both, 

 but chiefly the slaves, tend, and milk, as it may be called. 



JUrn 



