PLATE 100 



1 Position assumed by the animals of group A in the early stages of the experiments. 



2 Position assumed by the animals of group A in later stages after the conditioned response 

 has become inhibited. 



3 The dachshund type, an animal of group A, which is entirely inhibited under laboratory 

 conditions. 



4 An animal of group B, German shepherd, alert and highly active. These dogs continue 

 to give conditioned salivary responses for a long period of time, and become disturbed by 

 repeated presentations of negative signals. 



548 



