PRIMITIVE TYPES OF INTELLIGENCE 183 



aquarium quickly rushed, in obedience to its proclivity to 

 shun the light, into the dark corner where it got into difficul- 

 ties with the devil fish. Bethe now interfered and freed the 

 crab from its captor and put it back hi the aquarium. Back 

 the crab went again into the arms of the enemy. Five 

 successive times it repeated the performance (and another 

 individual did the same six times) without learning to avoid 

 the retreat of the devil fish. 



In another experiment a piece of meat was placed in an 

 aquarium containing some hungry crabs, and the hand of 

 the experimenter was held over the meat. ^Tienever a 

 crab seized the food the creature was maltreated and driven 

 away; it was thought that if the crab were capable of learning 

 it would come to associate the sight of the experimenter's 

 hand with the painful experience following the seizure of 

 the meat and keep at a distance. After several such ex- 

 periences it went after the meat as at first, and Bethe 

 concluded that the creatures were nothing but "reflex 

 machines," without a glimmer of intelligence. 



These few experiments by which the intelligence of the 

 crab is summarily disposed of, form an almost amusing 

 contrast to the long, detailed and exhaustive work on the 

 anatomy and physiology of the nervous system. The 

 experiments are obviously inadequate, not only because 

 they are much too few in number, but because they do not 

 afford the best opportunities for bringing out whatever 

 power of forming associations a crab may possess. In the 

 first experiment, granting that the crabs were not more 

 afraid of Bethe than of the devil fish, as they had apparently 

 as much reason for being, it would have been necessary for 

 the crab to inhibit a strong instinct before it could manifest 

 any tendency it may have acquired to avoid the dark corner 

 with its sinister occupant. A crab when afraid makes for a 



