OF THE INTELLIGENCE AND OF INSTINCT. 183 



suming his former dress, the bison again recognised him as 

 its master. Two rams living together in harmony, will, on 

 being shorn, attack each other as if they were perfect 

 strangers. The sagacity of the dog and elephant is well 

 known ; so also is that of the ape, but this is confined as 

 regards it to youth, for with age it progresses not, but often 

 becomes morose and savage. 



338. Some animals possess the power of intercommu- 

 nication, by means of which they express what they feel, and 

 make their feelings known to their comrades. Thus, certain 

 mammals and birds, which live in groups, sometimes place 

 a sentinel, which by peculiar cries warns the troop of the 

 approach of danger : the marmots and the flamingo do this ; 

 swallows seem also to have the power, by a peculiar cry, of 

 collecting together for mutual defence all the neighbouring 

 swallows, more especially when there is danger to their 

 young; and the observations made on bees by Huber, La- 

 treille, and other naturalists, leave little doubt that these 

 insects have the power of intercommunication. This is 

 seemingly not effected by any sound, but by touching each 

 other with their heads and antennae, and on this being 

 done, thousands will crowd to the point of danger. In the 

 obstinate wars which one colony of ants will sometimes carry 

 on against another, individual ants have been seen thus to 

 give such signals as to change the route of a whole army; 

 and observers worthy of every credit assure us, that indi- 

 vidual ants have been seen to quit the main body, and repair- 

 ing to the hillock, return with strong reinforcements. 



339. But if the faculties we have spoken of explain more 

 or less satisfactorily the actions of man and animals, there 

 are others which, in the existing state of our knowledge, 

 admit of no explanation, and which lead us to suppose that 

 such animals possess organs of sense of a kind unknown to 

 us. Neither instinct nor intelligence can explain the course 

 of the swallow and carrier-pigeon, transported hundreds of 

 miles from their locality, towards which they fly, when let 

 loose, in a line as straight as if it lay before their eyes. The 

 dog and horse seem to retrace their course, when lost, 

 by the ordinary senses ; but this cannot be the case with the 

 carrier-pigeon flying in a straight line from Bordeaux to 

 Brussels. 



340. Relations between the Intellect and the Brain. 

 We know nothing of the cause why certain intellectual and 



