680 O. I). AXDERSOX 



central nervous activity. Although the response in the post- 

 operative period was absent in the great majority of cases, 

 when it did appear it was remarkably retarded. Normally 

 the saliva begins to flow briskly within 4 seconds after the 

 stimulus is started. Following operation, the saliva began 

 slowly to flow only after 12 seconds (a retardation of 200 

 per cent). 



The dog's appetite did not seem to be appreciably affected 

 throughout the greater part of the experiment. No loss of 

 weight occurred. Appetite did wane, however, during the 

 terminal phase of the deficiency. The C-R experiments, since 

 they involved the salivary food-taking response, were then 

 abandoned. Twenty days before the dog died tetanic con- 

 vulsions were seen. This was 6 months after the operation. 

 The convulsions occurred almost daily and were alleviated 

 temporarily by parathormone (Collip) 25 units, and intra- 

 venous calcium lactate given during the seizure. Just before 

 an attack the dog was in a state of stupor. He showed no 

 response when his name was called or when he was patted. 

 He was also apathetic to a moderate electric shock on the 

 foreleg and to pinching by forceps. 



The autopsy showed an absence of parathyroid tissue. 

 Apparently there occurred a gradual absorption of the ex- 

 ternal parathyroids left intact at the operation, but the 

 deficiency in parathyroid secretion was not evident until 6 

 months after the operation. It is therefore reasonably certain 

 that the effects of the operation upon the C-R were due to 

 a deficiency of thyroid rather than parathyroid secretion. 



Dog 869 9, b as s ethound X shepherd F,. Since the results 

 in the previous case were based on the salivary reflex, the 

 motor reflex was used in dog 869. The conditioned stimuli 

 were Met. 120 (positive) and Met, 42 and Met. 28 (negative). 

 The standardization period was 13 months in length. 



This animal was most active and alert in all reactions. She 

 was what is known as a good watch dog, running about and 

 barking violently at the slightest unusual sound, although 



