Ants. 37 



they remained in perfect health, while but for the 

 slaves they would have perished in two or three 

 days. Except the slave-making ants, and some of 

 the beetles which live with ants, I know no case 

 in nature of an animal having lost the instinct of 

 feeding. 



8. In the Amazon Ants, the so-called workers, 

 though thus helpless and idle, are numerous, ener- 

 getic, and in some respects even brilliant. In another 

 slave-making ant, StrongylognatJius, the workers are 

 much less numerous and so weak that it is an un- 

 solved problem how they contrive to make slaves. 

 In the genus StrongylognatJius there are two 

 species, vS". huberi and S. testaceus. S. huberi, which 

 was discovered by Forel, very much resembles 

 Polyergus rufesccns in habits. They have sabre- 

 like mandibles, like those of Polyergus, and their 

 mode of fighting is similar, but they are much 

 weaker insects ; they make slaves of Tetramorium 

 cczspitum, which they carry off as pupae. In attack- 

 ing the Tetramoriums they seize them by the head 

 with their jaws just in the same way as Polyergus, 

 but have not strength enough to pierce them as the 

 latter do. Nevertheless, the Tetramoriums seem 

 much afraid of them. 



9. The other species, Strongylognathus testaceus, 

 is even weaker than S. huberi, and their mode of life 

 is still in many respects an enigma. They also 

 keep the workers of Tetramoriuin in, so to say, a 

 state of slavery, but how they procure the slaves is 



