92 



ANN HAVEN MORGAN 



were a factor and that certain frogs were especially sensitive to 

 heat. This opinion was further justified by a series of tests 

 repeated over and over on particular individuals. The right 

 foot of each of these frogs was stimulated by hot water whose 

 temperature ranged from 25°C. to 50°C. and at intervals of 5°, 

 the experiment being repeated seven times consecutively (table 3) . 

 This was done to find out whether each frog would preserve 

 its individual eccentricities toward heat in successive tests and 



TABLE 3 

 Responses in seconds of two frogs to hot water whose temperature was increased by 

 5°C. at each stimulation. Each series repeated consecutively seven times. Feet 

 normal. Reaction allowance, 30 seconds. Stimulation time, 2 minutes, co = 

 no reaction 



on different days. Two records selected (no. 11, 1; no. 11, 2) 

 were of a frog of average susceptibility and the tests 1 and 2 

 were made on different days, and the third (no. 14, 1) was chosen 

 because it showed unusual sensitiveness. Both types were fairly 

 common and the sensitiveness or dullness persisted with repeated 

 stimulations in nearly all the animals tested. These results 

 indicated that the speed of applying stimuli is not the only factor 

 present in quick or slow responses. 



The heat responses were characteristically sharp upward jerks 

 of the leg. As it was pulled upward the toes were held together 



