6 QUATERCENTENARY STUDIES IN PATHOLOGY 



refused food almost entirely, in consequence of which they lost from 

 30-40 % of their body weight Sooner or later, these dogs showed 

 a very acute attack of symptoms which were usually fatal. Other 

 animals ate sparingly, and were not affected so acutely. Some dogs, 

 on the other hand, ate plentifully of certain foods and suffered only 

 mildly. The ingestion of flesh was found to be the immediate cause of 

 the onset of symptoms. Many dogs, having recovered from an attack, 

 would afterwards refuse flesh and remain perfectly normal until again 

 induced to take it, when another attack would result. Other dogs 

 seemed from the very first to know instinctively that flesh was hurtful 

 to them, and would absolutely refuse to eat it, and if offered no other 

 food, starve instead. 



Pawlow and his co-workers sum up their result regarding these 

 observations by stating that "dogs in which the portal blood flows 

 directly into the vena cava without passing the liver cannot stand 

 flesh diet without the development of severe nervous symptoms which 

 often terminate in death." 



In the dogs which did not show symptoms, /^j/ mortem examination 

 revealed a collateral circulation to the liver and a small opening between 

 the veins. The presence of this collateral circulation in von Karltreu's 

 dogs undoubtedly explains the absence of the symptoms reported by him. 



A careful chemical examination of the urine of these dogs was made 

 by Nencki and Hahn. A relative increase in ammonia and uric acid, 

 and a relative decrease in urea, were usually found. The urine was 

 mostly alkaline in reaction. The most noteworthy abnormal change 

 however, consisted in the presence of carbamic acid^ and in greatest 

 amount when the above symptoms were present. This led these 

 workers to think that poisoning by carbamic acid might be the primary 

 cause of the symptoms. To test this hypothesis, studies were next made 

 of the pharmacological action of carbamic acid in dogs. When a five 

 per cent, solution of carbamate of sodium in physiological saline was 

 injected intravenously into normal dogs the following effects were noted. 

 With 0*25 grm. carbamic acid per kilogram body weight the dog 

 became drowsy and somewhat ataxic in his gait ; with a dose of 0*3 

 grm. per kilogram the dog became more or less excited, sometimes 

 excessively so ; the movements were ataxic, and the sense of vision was 

 lost, but hearing was normal. The skin was anaesthetic, and sometimes 



(270) 



