GENETIC TYPE AND THE ENDOCEIXES 549 



case of animal 83 9 , however, by the time sixteen negatives 

 had been applied, the positive had disappeared. Similar con- 

 ditions occurred in all dogs of this group, even if the negative 

 was not presented. Another bassethound, 1426 $ , is a specific 

 example. The negative signal was withheld in order to deter- 

 mine if the performance in this type of dog would then follow 

 the same course as that of 83 9 , which it did. It is extremely 

 difficult to determine the limits of analytical ability in these 

 dogs by this method of experimentation. 



Reactions of the lethargic group to intense auditory stimuli. 

 Since only a mild reaction to the clicker signal was elicited 

 on the first presentation, a loud buzzer or bell was introduced 

 after the performance had advanced to determine the inertia 

 of the nervous actions of defense and orientation. The new 

 signal caused little noticeable reaction and only a slight 

 change in breathing (text-fig. 93, fig. 1). Here again, the 

 dog's habitual mode of reaction in the laboratory is the 

 important factor. By this time the animals are well acquainted 

 with the laboratory, they have had only food in this environ- 

 ment, and they have made all the adjustments necessary. 

 They are unprepared for any change and only a long series 

 of accessory disturbances will arouse them to action. This 

 seems to be based on a narrowing down or concentration of 

 the neural patterns. The reaction in another situation, how- 

 ever, as for example in the outdoor environment, would un- 

 doubtedly be quite different. 



Reactions of the lethargic group to other signals. After 

 the adjustment to the auditory signal had been studied for 

 a period, tactile and visual stimuli were introduced to deter- 

 mine if the reactions would follow the same general procedure. 

 These signals were presented between the clicker signals. A 

 black horizontal line on the charts (text-figs. 89, 90 and later) 

 indicates the experimental periods in which these signals 

 were introduced and the relative number of experimental 

 periods during which they were continued. Animal 83 9 did 

 not develop a conditioned reaction either to the tactile or 

 visual signal, but one cannot conclude from this that the 



