582 W. T. JAMES 



the shock strong enough to elicit the avoiding movement of 

 the foreleg, the secondary coil was placed 10 centimeters 

 away from the primary. The induced shock at this distance 

 from the primary coil was found too weak to elicit the re- 

 action in any of the animals. The secondary coil was then 

 moved toward the primary in steps of i centimeter. At each 

 step the shock was tried to determine whether it was intense 

 enough to elicit the reaction. If the shock was strong enough, 

 the leg was raised as soon as the shock was applied. The 

 number of centimeters distance the secondary coil was from 

 the primary when the shock was strong enough to elicit the 

 reaction was considered the shock value for that animal. 

 The shock used in determining this value was a continuous 

 shock and not a single break or make shock. These values 

 are shown in column 2 of table 7. As a rule, the dogs of 

 group A required a slightly stronger shock to produce a 

 brisk flexion of the foreleg than did the dogs of group B. 

 For example, the German shepherd of group B gave a brisk 

 movement when the secondary coil was 8 centimeters from 

 the zero reading, while the bassethound of group A did not 

 respond until the secondary coil was 6 centimeters from the 

 zero reading. This is the lowest reading. A value of 8.5, made 

 by a bassethound-German shepherd hybrid, 1152 $ , was the 

 highest reading (weakest shock). The other dogs responded 

 to values of 7 and 7.5. 



The reactions to the liminal shock showed significant dif- 

 ferences. In the animals of group A even the initial reaction 

 was limited to the distal leg segment, while in those of group 

 B a more general reaction, involving all leg segments and 

 postural systems of the head and neck, occurred. This would 

 indicate a difference of irradiation of excitation throughout 

 the nervous system, and also a different functional relation- 

 ship between the various levels of neural organization. Fur- 

 thermore, in group A the after-discharge of the excitation 

 was weak, while in group B the activity was extensive and 

 in many cases continued so long that it was necessary for 

 the experimenter to enter the room to quiet the animal. This 



