CHANGES IN THE BLOOD IN THE KIDNEYS. 177 



not coagulate readily, and that it is impossible to obtain 

 fibrin from it in the ordinary way by stirring with rods. 1 It 

 is difficult in the present state of our knowledge to give any 

 satisfactory physiological explanation of this disappearance 

 of fibrin in the kidneys. Absence of fibrin has also been 

 noted by Lehmann in the blood of the hepatic veins.* 



Reference has already been made to the researches of 

 Bernard, showing that the blood coming from many of the 

 glands during their functional activity is but little darker 

 than arterial blood. 3 The action of the kidneys is constant, 

 and the quantity of blood which they receive is enormous. 

 Unless the function of these organs be disturbed, the blood 

 p'assing through them cannot be deoxygenated, and is con- 

 sequently red, containing a large quantity of oxygen and 

 a very small proportion of carbonic acid. This fact we have 

 often noted, and it has been observed by all who have exam- 

 ined the renal veins in living animals. In comparative 

 analyses for gases of the blood of the renal artery and vein, 

 Bernard found, in one examination, no carbonic acid in 

 either specimen ; the proportion of oxygen being twelve 

 parts per hundred in volume for the artery, and ten parts 

 for the vein. These observations were made at a tempera- 

 ture of from 50 to 53 Fahr. Making the analyses at about 

 the temperature of the body, 104 to 113, the quantity of 

 carbonic acid was three parts for the artery and 3*13 parts for 

 the vein ; and the proportion of oxygen was 19*46 parts for 

 the artery and 17*26 parts for the vein. TVhen the secretion 

 of urine was arrested by irritation of the kidney, the blood 

 became black in the vein, and the quantity of oxygen dimin- 

 ished, with a corresponding increase in the proportion of 

 carbonic acid. 4 



These observations show that during secretion most of 



1 SIMON, Animal Chemistry, Philadelphia, 1846, p. 178. 



2 LEHMAXN, Physiological Chemistry, Philadelphia, 1855, Tol. i., p. 319. 



3 See page 21. 



4 BERNARD, Liquids de Vorganisme, Paris, 1859, tome ii., p. 160. 



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