536 W. T. JAMES 



The conditioned salivary reaction seems, therefore, to be 

 one observable factor of the total organismal reaction to 

 food. 



It is apparent that the behavior in this experimental con- 

 dition is mainly one of restraint. As soon as the dog enters 

 the room, activity is decreased, and the only real excitatory 

 factor after the animal is placed in the harness is food. The 

 animal responds to the signal only because it is presented 

 with food. If the food is delayed each time, the food taking- 

 reaction and the conditioned saliva also develop along latent 

 period in most dogs. From the biological point of view, food 

 is the only significant part of the environment, and the salivary 

 reaction alone is biologically of small import compared with 

 other reaction systems. It may be for this reason that the 

 response is so subject to inhibition. By presenting the signal 

 and food together, however, and then occasionally delaying 

 the food, we get an indication of the dog's nervous reactions. 

 In this way the animal remains in the process of adjustment 

 longer than would be the case were food delayed every time ; 

 and thus, as the experiment progresses, an opportunity is 

 afforded to study the phases of excitation as indicated by the 

 saliva and the inhibition of this reaction. 



In most cases, the negative signal, or a second signal with- 

 out food, was not presented until the nature of the positive 

 reaction had been determined. The negative was introduced 

 to indicate the intensity of the organismal setting for the 

 food, and the ease or difficulty with which this functional 

 system could be modified. In order to be certain that the 

 same general behavioral pattern as in the response to the 

 positive signal would be involved, the telegraph clicker was 

 also used as the negative signal, but with a different fre- 

 quency (positive 120; negative 50 or above). It had been 

 determined by preliminary experiments that if the second 

 signal differed widely from the first, the original behavioral 

 pattern would not be involved, that is, the tendency would 

 be toward orientation or escape rather than to the food pan. 



