DO ANTS FORM PRACTICAL JUDGMENTS ? 343 



stimuli. When, under identical conditions, one member of a 

 group responds to a stimulus in one way and yet other members 

 respond to a similar stimulus in a different manner the response 

 would be individualistic. When an animal faces a situation for 

 which it has no class response and yet almost immediately makes 

 an individualistic response which overcomes the difficulty, it has 

 formed what Hobhouse calls a practical judgment. 



It seems to me that this is what the ants did in the case recorded 

 here. When a crack was made into their brood chamber they 

 were face to face with a situation for which they had no class 

 response. After awhile one to a few individuals made individ- 

 ualistic responses which resulted in the closing of the crack. To 

 those few ants the disturbance in the brood chamber had been 

 associated with the unclosed crack. To them the crack had 

 acquired a meaning. It had become a crack-to-be-closed and 

 they proceeded to close it. 



It is not claimed that the construction of a trash pile of hetero- 

 geneous material, nor even the building of a felted partition out of 

 special materials, indicates the formation of a practical judgment ; 

 for the forming of a trash pile by ants is, and the modeling of a 

 partition may be, an instinctive action. But the utilization of 

 these instinctive activities, without a preliminary period of experi- 

 mentation, to meet adequately conditions for which the ants had 

 no stereotyped response is what warrants the assumption that 

 they form practical judgments. 



It seems to me that in constructing the partial bridge, in remov- 

 ing the guards from the entrance and plugging it with cotton, and 

 in closing the crack to the brood chamber, at first with trash 

 piled on the outside and later with a wall built up from within, 

 the ants have responded to stimuli, not as ends in themselves, 

 but rather as means to ends. This would lift the act out of the 

 realm of instinctive behavior into that of the practical judgment. 

 Hull Zoological Laboratory, 



University of Chicago, August 17, 1907. 



Explanation of Figures. 

 Each represents a diagram of the top of a Janet nest : A, B, C are brood chambers ; 

 D is the water well ; E is the entrance to the nest ; a, b are cracks between the glass 

 covers ; c, d,faxe. edges of the glass cover of chamber C ; e is a crack across the top 

 of chamber C; the oblique shading represents the turkish toweling ; the horizontal 

 shading represents the glass covers. 



