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1 The reactions of the normal dog in the food taking salivary reflex situation. In the 

 first picture, the animal is unstimulated. At the right a stimulus (Met. 120) is sounding. 

 The stimulus in this case is to be followed by food. The graph below is a record of these 

 reactions and shows the conditioned flow of saliva to the Met. 120. Top line indicates head 

 movement; below, in order general body movement, respiration, saliva in 1/100 cc., metro- 

 nome signal, food, and time in seconds. 



2 Reactions of a dog in the conditioned motor or defensive reflex situation; at the left, 

 the animal in the unstimulated pose, and at the right, reacting by raising his right forelimb 

 to the sound of the Met. 120 to be followed by the shock. The graph below is a record of 

 these reactions. Top line, head movement; below in order respiration, movements of right 

 foreleg, metronome signal, shock, and time in seconds. 



3 A view showing the details of the recording apparatus. The wheel at the right of 

 the picture is the modified Flck work accumulator designed to register the magnitude of the 

 conditioned motor reflex. 



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