78 THE HUMANIZING OF THE BRUTE. 



We fail to see how the results of the sciences en- 

 umerated by Prof. Wheeler could ever change the def- 

 inition of intelligence developed in the preceding 

 pages, since that definition rests on totally different 

 grounds and belongs to a sphere which even a science 

 like physiology can only approach, but never reach. 

 The fact that intelligent actions can only proceed from 

 an inextended spiritual faculty is indeed a final verity, 

 which, it is true, may find a much deeper and more 

 adequate explanation as true human psychology ad- 

 vances, but which will never be changed in the point 

 it emphasizes. 



We have seen in the first part of this essay that the 

 essential criterion for discriminating instinctive and 

 intelligent actions from each other lies in the fact 

 whether or not the animal evinces consciousness of the 

 finality guiding its actions. This criterion we shall 

 apply in our present investigation, which proposes to 

 show that neither the lower nor the higher animals 

 betray the slightest vestige of intelligence. "High 

 animals" are distinguished from "low animals" by 

 the fact that the bodies of the latter are less different- 

 iated than those of the former. Practically the dis- 

 tinction will coincide with the division of the animal 

 kingdom into invertebrates and vertebrates. 



In order to establish the proposition that the lower 

 animals are void of intelligence we propose to enter 

 upon a most remarkable psychic contrast observed in 

 the life-history of two ant-species, Polyergus and For- 

 mica sanguinea. The latter easily holds the first place 

 among all ants and, in general, among all lower ani- 

 mals. This fact is freely granted by the best observ- 



