1879.] on the Eahits of Ants. 181 



for more than a year. Having separated a nest of F. fusca into two 

 halves, I put from time to time one of the ants from one half into the 

 other, and in every case she was amicably received ; while strangers 

 from another nest, although of the same species, were invariably 

 attacked. 



It is clear, then, that the ants recognize all their fellows in the 

 same nest, but it is very difficult to understand how this can be 

 effected. The nests vary very much in size, but in many species 100,000 

 individuals is by no means an unusual number, and in some instances, 

 even this is largely exceeded. Now, it seems almost incredible that 

 in such cases every ant should know every other one by sight. 



It has been suggested, in the case of bees, that each nest might 

 have some sign or password. 



The whole subject is full of difficulty. It occurred to me, how- 

 ever, that experiments with pupae might throw some light upon it. 

 Although the ants of every nest, say of Formica fusca, are deadly 

 enemies, still, if larva? or pupae from one nest are transferred to 

 another, they are kindly received, and tended with, apparently, as 

 much care as if they really belonged to the nest. In ant warfare, 

 though sex is no protection, the young are spared — at least, when they 

 belong to the same species. Moreover, though the habits and dispo- 

 sition of ants are greatly changed if they are taken away from their 

 nest and kept in solitary confinement, or only with a few friends, still, 

 under such circumstances, they will carefully tend any young which 

 may be confided to them. Now, if the recognition were effected by 

 means of some signal or password, then, as it can hardly be supposed 

 that the larvae or pupae would be sufficiently intelligent to appreciate, 

 still less to remember it, the pupae which were entrusted to ants 

 from another nest, would have the password, if any, of that nest, 

 and not of the one from which they had been taken. Hence, if the 

 recognition were effected by some password or sign with the antennae, 

 they would be amicably received in the nest from which their nurses 

 had been taken, not in their Own. 



I took, therefore, a number of pupae out of some of the nests of 

 Formica fusca and Lasius niger, and put them in small glasses, some 

 with ants from their own nest, some with ants from another nest of 

 the same species. 



The result of my observations was that thirty-two ants belonging 

 to Formica fusca and Lasius niger, removed from their nest as pupae, 

 attended by friends, and restored to their own nest, were all amicably 

 received. What is still more remarkable, of twenty-two ants belong- 

 ing to Formica fusca, removed as pupae, attended by strangers, and 

 returned to their own nest, twenty were amicably received, though, in 

 several cases, after some hesitation. 



Of the same number of Lasius niger, developed in the same 

 manner, from pupae tended by strangers belonging to the same species, 

 and then returned into their own nest, seventeen were amicably 

 received, three were attacked, and about two I felt doubtful. On the 



