JOSEPH H. PRATT 



exogenous purin nitrogen. It may vary in normal persons from 8 to 74 

 per cent (McClure and Pratt). When hypoxanthiii was the purin sub- 

 stance administered, Ackroyd(a) found the percentage varied from 21 to 

 72 per cent, and the same individual gave different results on different 

 occasions. Even when a very large amount of purin nitrogen is given 

 in the food the uric acid output in any one day is rarely above 1.5 grams 

 and is usually below 1 gram. If the purins of the food are directly ex- 

 creted in the form of uric acid it seems remarkable that the feeding of 

 very large quantities of purins produces such a relatively slight increase 

 in the output of uric acid. 



Mares (a) found an increase of the uric acid excretion during the first 

 hour after meat was given to a fasting subject. The output reached its max- 

 imum during the fifth hour and then gradually sank. The increase of the 

 urea began in the third hour after the ingestion of meat. Mares' (a) (6) (c) 

 advanced the view that the increased output of uric acid after eating purin- 

 containing food was due chiefly to the activity of the digestive organs. 

 The fact that meat produces a more marked increase of uric acid output 

 than purin-free albumin Mares' attributes to the greater stimulation of 

 the digestive glands by the purin. It is a proved fact that albumin, free 

 from purin, increases the uric acid excretion (Mares', Mendel and Brown, 

 Mendel and Stehle, Host (a), Lichtwitz(Z), Maurel, Taylor and Rose). 

 Mares' regards this as evidence that the increased amount of uric acid ex- 

 creted during the first few hours after the ingestion of meat does not come 

 from the purins of the meat. The administration of carbohydrates also 

 produces an increased output of uric acid, and this supports Mares' theory. 

 Smetanka found that the slight increase which followed the ingestion of 

 honey was greater than that caused by starch. It is evident that starch 

 would call forth greater demands on the digestive organs, and Smetanka 

 attributed the greater output caused by honey to stimulation of the glyco- 

 genie function of the liver. This is certainly a modification of Mares 

 theory. 



That the exogenous and endogenous uric acid formation cannot be 

 sharply separated seems evident, but that the so-called exogenous uric acid 

 is largely produced by the activity of the digestive glands seems doubtful. 

 The secretions poured into the intestine contain purin bases, but even if all 

 were absorbed unchanged this would account for but a small part of the 

 uric acid output (Brugsch and Schittenhelm(d)). 



If MareS theory were correct it would seem to follow that in starva- 

 tion the uric acid excretion would fall to a very low level as the activity 

 of the digestive organs is at a minimum. There is always a marked drop 

 in the uric acid during the first few days of a fast. A marked fall on the 

 second day was observed by Schreiber and Waldvogel, F. Benedict and 

 others, but there is a rise as fasting progresses (Cathcart(c)). During 

 Benedict's study of a fast of thirty-one days, there were many days when 



