50 Journal of Cojnparativc Neurology and Psychology. 



make evident the justification of our criticism. His fi>st ex- 

 periment was to place a crab in a basin in the darkest corner of 

 which there was an Eledone (a cephalopod). The crabs, be- 

 cause of their instinct to hide, moved immediately into this 

 corner and were seized by the Eledone. Freed from its grasp 

 one crab returned repeatedly five times, another six, to the dark 

 and the enemy, showing, as Bethe thinks, that it had not 

 profited by experience. It is to be emphasized, however, that 

 to have done this latter in the way Bethe thought possible, it 

 would have been necessary that the crab inhibit its instinctive 

 action. This inhibition could take place only if, first, a repre- 

 sentation of the pain of the seizure by the Eledone were present, 

 and second (and essentially), if the representation were the 

 '^stronger" ; the other possibility, that the representation should 

 ■occur and yet be overcome by the instinct, is accordingly not 

 disproved by Bethe's experiment. The same criticism applies 

 also to his second method that, notwithstanding maltreatment 

 on each such occasion, the crabs repeatedly seize food when 

 offered. 



The criticism above made is quite in agreement with that 

 principle of method for comparative psychology which is in re- 

 ality very simple, but not always observed, that in any instance 

 where the question of the presence of consciousness in any 

 species is admittedly to be decided by experimentation, this 

 question must take a particular form, and our efforts must be 

 directed to the establishment of the presence or absence of 

 some definite kind of consciousness, e. g. , associative memory 

 between constructs of two sense fields, conceptual reasoning, 

 etc. 



Yerkes in his experiments with the crawfish made use of 

 the labyrinth method. The subject could escape from a box 

 into the aquarium only by "choice of a certain passage." The 

 "choice" consisted in or was manifested by learning (by repeat- 

 ed experience) to avoid the blocked passage and gain the 

 aquarium by the most direct path. Accordingly all conflict, 

 requiring inhibition, between the two elements or "constructs" 

 to be associated, viz., "correct path" and "aquarium," was ab- 



