ANIMAL AND RATIONAL INTELLIGENCE 197 



of method for attaining these ends. Further, in order 

 that evidence may be carefully examined, it is needful 

 to narrow observation to the facts of individual life, 

 without reference to the struggle for existence, and 

 the play of passion, unfavourable to manifestation of 

 intelligence in man or in beast. When this is done, 

 it becomes clear that the ant is restricted in action by 

 the limits of instinct, whereas the dog advances 

 beyond this limit, making acquisitions under training. 

 A physical basis for this contrast is readily found, by 

 reference to the range of sensibility at the command of 

 each life. The whole contrast does not, however, seem 

 accounted for in this way. An animal with such range 

 of vision as the dog possesses, has many advantages. 

 Guided by touch, quite marvellous in delicacy, the ant 

 nevertheless encounters many limitations which do 

 not restrict the animal guided by sight. Thus, the 

 consequences to the ant from injury or loss of the anten 

 nae are serious. Dr. Romanes has described the result 

 in the following terms : Their removal produces an 

 extraordinary disturbance in the intelligence of the 

 animal. An ant so mutilated can no longer find its 

 way or recognise its companions. ... It is also unable 

 to find food, ceases to engage in any labour, and loses 

 all its regard for larvae, remaining permanently quiet 

 and al most motionless. Place in contrast with this 

 animal a blind dog, and in contrast with both a blind 

 man. By differences in result, we can infer differences 

 in the measure and kind of power at command. This 

 test will prove still more exact, if we imagine the dog 

 deprived of the power of smell, the organ in which he 

 is pre-eminent, while retaining sense of sight. The 



1 Animal Intelligence, p. 142. 



