676 O. D. ANDERSON 



reaction was probably due in large part to the further train- 

 ing, since this efficiency continued to increase after the ex- 

 periment. 



Dog 881 offers a special case, since this animal was a 

 * 'neurotic." The extract increased motor activity enormously 

 during the experiment, but curiously enough diminished the 

 values of the salivary C-R. This lessened salivary C-R value 

 is undoubtedly linked with the experimental neurosis since 

 there was a definite gradual loss of the conditioned reaction 

 with the passage of time, apart from the extract. This "in- 

 hibitory" tendency in experimental neurosis has been noted 

 in the dog by Pavlov and his co-workers, and also in the 

 sheep, reported by Anderson and Liddell. 



The increase in the magnitude of the motor C-R observed 

 in clog 868 is in essential agreement with the observation 

 of Zawadowsky and his associates, and also with that of 

 Kleitman and Titelbaum, although the observation of the 

 former, that the C-R shows an initial depression, was not 

 confirmed. 



The fact that the conditioned salivary C-R decreased in 

 one animal, 881, during the extract treatment, is not a real 

 disagreement since the result cannot reasonably be attributed 

 to the substance. On the other hand, the heightened nervous- 

 ness in this dog and in dog 868 (clear cases of heightened 

 excitability), tends to confirm the findings of all these workers. 



Finally, then, we have tested the salivary C-R in two and 

 the motor C-R in one normal dog. Each animal was fed 

 thyroid extract for a specific length of time. The efficiency 

 (percentage of correct responses) of the positive salivary 

 C-R was somewhat diminished by thyroid treatment in one 

 dog but was not affected in the other. The efficiency of the 

 motor C-R was also not affected in the third dog. The per- 

 centage of correct responses to the negative stimuli was, 

 however, noticeably increased in each animal. 



The magnitude of the motor C-R was appreciably increased 

 while that of the salivary C-R was unaffected. In the former 



