SIE JOHN LTJBBOCE ON ANTS, BEES, AND WASPS. 611 



every other one by sight. Neither does it seem possible that all 

 the ants in each ease should be characterized from those of other 

 nests by any physical peculiarity. 



It has been suggested that ants may recognize one another by 

 scent. This, however, I think, cannot be the explanation. For 

 instance, when intoxicated, ants were recognized; surely the 

 whiskey must have obliterated any natural odour. Again, I have 

 kept ants for forty-eight hours in an atmosphere strongly scented 

 with musk ; but when returned to the nest they were recognized 

 without the least doubt or hesitation. 



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 on the 

 subject. Although the ants of every nest, say oi Formica fmca, 

 are deadly enemies, still if larvae or pupse from one nest are trans- 

 ferred to another, they are kindly received, and tended with ap- 

 parently 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 disposition of ants are greatly changed if 

 they are taken away from their nest and kept in solitary con- 

 finement, or only with a few friends, still, under such circum- 

 stances, they wiU carefully tend any young which may be confided 

 to them. Now if the recognition were efiected by means of 

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

 the larvae or pupse would be sufficiently intelligent to appreciate, 

 stiU less to remember it, the pupae which were intrusted 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 efiected by some password or sign with the 

 antennae, they would be amicably received in the nest from which 

 their nurses had been taken, but not in their own. 



In the first place, therefore, I put, on the 2nd of September 

 1877, some pupae from one of my nests oi Formica fusca with a 

 couple of ants from the same nest. On the 27th I put two ants, 

 which in the meantime had emerged from one of these pupse, into 

 the nest at 8.30 a.m., marking them with paint as usual. At 9 

 they seemed quite at home ; at 9.30, ditto ; at 10, ditto ; and they 

 were nearly cleaned. After that I could not distinguish them. 



On the 29th another ant came out of the pupa-state ; and on 



