54 Chapter II. 



follow the habit of invading nests of certain smaller 

 species of Formica, and of rearing the robbed worker 

 pupae, partly at least, as auxiliary ants for their own 

 colony. It is, moreover, a constant characteristic of 

 F. sanguined to have rather a small number of slaves, 

 if compared with those of the Amazons. With these 

 latter the slaves are far more numerous than the 

 masters, with the former it is the reverse. Likewise, 

 the specific military tactics are everywhere equally 

 constant with both ant species. From the Alps to 

 England and Scandinavia, from Holland to the 

 Caucasus, F. sanguined nowhere changes her habits 

 and customs. Even her North American sub-species 

 (rubicunda Em.) shows the same instinct of slave- 

 making, and this in the same specific form. The only 

 difference is, that one of the two European slave 

 species, F. fusca, is represented in the North American 

 rubicunda colonies by a closely allied variety, namely 

 by F. subsericea. 1 Since the separation of North 

 America from Europe was completed in the Tertiary 

 age, the enslaving habits of the sanguineas and their 

 military tactics must have been essentially the same in 

 the Tertiary as they are today. This is the most natural 

 explanation for the specific uniformity of that instinct 

 in the different parts of the globe. One thing, how- 

 ever, is certain : if the impulse of slavemaking and the 

 specific military tactics of F. sanguinea were due to 

 the intelligence of the ants, or if they were even in the 

 slightest degree dependent on it, such a specific uni- 

 formity existing for thousands of years would be 

 utterly inconceivable. 



*) See Wasmann, "Kritisches Verzeichniss der myrmekophilen und 

 termitophilen Arthropoden" (1894), p. 163 ff. 



