586 



W. T. JAMES 



On the other hand, the animals of group B remained active 

 and alert, and there was a tendency to keep the leg- or the 

 whole body in motion (text-fig. 102, fig. 1). There was a 

 tendency for some of these dogs to hold the foot in the 

 avoiding position during the experiments and never place it 

 on the floor. Others held the leg in a half flexed position 

 suggesting- a "set" to react when the signal was given. One 



Text-figure 102. (1) Becord showing the excitable condition of many of the 

 dogs of group B in the conditioned avoiding situation. The excitable nature 

 is indicated by variable head movements and spontaneous movements of the 

 foreleg. (2) Becord of an animal of the mid-group differentiating between a 

 sound with a frequency of 120 vibrations per minute and one of eighty-four 

 vibrations per minute. The former is presented with food while the latter is 

 accompanied by a shock on the foreleg. Only well balanced animals of the 

 mid-group can make such differentiations. 



of these animals is shown in plate 101 (fig. 2). Occasionally 

 these animals raised the leg, as if the nervous excitation had 

 suddenly arisen releasing the avoiding movement. The ani- 

 mals which held the leg up all the time were those most 

 severely disturbed by the shock when it was first applied. 

 They retain this intense excitement later, even though they 

 learn to avoid the shock. No. 819 S avoided the shock but 

 barked continually during the intervals as well as during 



