ANIMAL AND RATIONAL INTELLIGENCE 199 



thus obtained cannot be regarded as belonging to the 

 natural history of evolution, they are of the highest 

 value as bearing on possession of Intelligence. Our 

 observations now become closer, more constant, and 

 more exact. We ascertain the capabilities of animals 

 when, in companionship with man, they are aided in 

 development of intelligence by his guidance and train 

 ing, even by sharing in his work. There is thus large 

 gain in passing from natural conditions to artificial. 

 In classifying together the dog and horse, the monkey 

 and ape, we are, so far, treating analogies of structure 

 as secondary, in order that observation may be con 

 centrated more directly on manifestations of intelli 

 gence. Each species named gives evidence of a power 

 of discrimination superior to sensibility. Ability to 

 interpret sensory experience appears in their recog 

 nition of some meaning in the word uttered by us. 

 This supplies distinct evidence of Intelligence, provided 

 that the word employed be something more than the 

 reproduction of a sound for food or drink, used by the 

 animal itself even in its natural state. Sounds natural 

 to animals as expressive of hunger, or as indicative of 

 pleasure when food is within sight, afford no testi 

 mony for intelligence. What we need is some evidence 

 of advance beyond sensibility, and beyond utterance 

 of the inarticulate sounds which belong to all animals 

 above the fishes. 



In dealing with comparative intelligence, we may 

 have to allow to the dog superiority over the ape, so 

 little does analogy, or even homology, of structure 

 seem to guide in applying tests of intelligence. On 

 the other hand, passing from configuration of body to 

 structure of brain, the form of this organ may differ 



