PROCEEDINGS OF SCIENTIFIC SOCIETIES. 139 
but in some species 100,000 individuals may probably be 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 knows overy 
other one by sight; neither does it seem possible that all the ants in each 
nest should be characterized from those of other nests by any peculiarity. 
It has been suggested in the case of bees that each nest might have some 
sign or pass-word. The whole subject is full of difficulty. It occurred to 
Sir John, however, that experiments with pup might throw some light on 
the subject. Although the ants of every nest, say of Formica fusca, are 
deadly enemies to others, still if larvee or pupe 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 dispositions 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 in 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 pass-word, then, as it 
cau ,hardly be supposed that the larve or pup would be sufficiently 
intelligent to appreciate, still less to remember it, the pupe which were 
entrusted to ants from another's nest would have the pass-word, if any, of 
that nest, and not of the one from which they had been taken. Hence, if 
the recognition were effected by some pass-word or sign with the antenne, 
they would be amicably received in the nest from which their nurses had 
been taken, but not in their own. He therefore took a number of pupe 
out of some of his 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 results were that thirty-two ants - 
belonging to F’. fusca and L. niger, removed from their nest as pupe, 
attended by friends and restored to their own nest, were all amicably received. - 
What is still more remarkable, of twenty-two ants belonging to F’. fusca, 
removed as pup, attended by strangers, and returned to their own nest, 
twenty were amicably received. As regards one, Sir John was doubtful; 
this last was crippled in coming out of the pupa-case, and to this perhaps 
her unfriendly reception may have been due. Of the same number of 
L. niger, developed in the same manner, from pupz tended by strangers 
belonging to the same species, and then returned into their own nest, 
seventeen were amicably received, three were attacked; about two Sir John 
felt doubtful. On the other hand, fifteen specimens belonging to the same two 
species, removed as pup, tended by strangers belonging to the same species, 
and then put into the strangers’ nest, were all attacked. The results may 
be summarised as follows:—Pupz brought up by friends and replaced in 
their own nest—attacked, 0; received amicably, 33. Pupe brought up by 
