1886.J Origin of Uric Acid in the Animal Body. 485 



form of sodium urate, and, when deposited from the 

 blood during life in any tissue, it is also as sodium urate 

 in its characteristic crystalline form. 



Prop. III. — The daily quantity of uric acid in relation to their 

 body-weights secreted by different animals varies ex- 

 tremely. In some, as the carnivorous mammalia, the 

 ratio may be less than 1 to 1,000,000, whereas, in others, 

 as birds, it may be as 1 to 85. In man it may be 

 regarded as about 1 to 120,000. 



Prop. IV.- — The quantity of uric acid contained in the blood of 

 different animals has little relation to that secreted by 

 the kidneys. In birds, secreting daily so large a 

 quantity, the blood is often found to be as free from 

 uric acid as it is in animals wh^se daily elimination of 

 uric acid is excessively small. 



Prop. V. — When uric acid is absorbed from the alimentary canal 

 the blood becomes strongly impregnated, and, in fact, 

 often almost saturated with it, so that its presence is 

 readily discovered by any ordinary test. 



Prop. VI. — One cause of the appearance of an unusual quantity of 

 uric acid in the blood of birds in health is the presence 

 of uric acid in the water they drink, and occasionally in 

 their solid food. 



Prop. VII. — When uric acid is taken into the stomach of man, or 

 other animals, the secretion of this principle from the 

 kidneys is not increased, although at the time the blood 

 may be rich in it. 



Prop. VIII. — Uric acid is found in varying quantities in the blood 

 obtained from different veins in the same animal. It is 

 found in larger quantity in that from the efferent renal 

 veins of birds than in that from the portal afferent, or 

 from the jugular veins ; and the same test which freely 

 exhibits nric acid in the blood from the former, often 

 fails to show it at all in that from the latter two. 



Prop. IX. — The quantity of uric acid secreted daily by the kidneys 

 of a bird is in close relation to the quantity of nitrogen- 

 ised food taken during the time. 



Having brought forward proofs to confirm these propositions 

 severally, the author draws the following conclusion, viz., that every 

 argument is in favour of the hypothesis that uric acid is formed by 

 the kidney-cells, in the form of ammonium urate, and that the traces 

 of sodium urate ordinarily found in the blood are the result of a 

 necessary absorption, slight in amount, of the ammonium urate from 

 the kidneys into the .blood, and its subsequent conversion by that fluid 

 into sodium urate. 



