140 SANGUIFICATION. L.ECT. VII. 



medium constantly at the same degree of heat. I saw that 

 oxygen in part disappeared, that it was replaced by carbonic 

 acid, and that at the bottom of the receiver was deposited 

 a great number of reddish flocculi; yet the primitive liquid 

 was limpid and scarcely coloured. These flocculi on exa- 

 mination did not appear to me to be identical with fibrine. 

 Nevertheless, I do not wish to conclude from these negative 

 results that the principle, on which my experiments were 

 founded, was false. It is a subject which claims very long 

 and very varied researches. 



Changes in the Blood of the Capillaries. Let us return 

 to our first subject. In the act of nutrition, a part of the 

 oxygen of the arterial blood disappears, and is replaced by 

 an excess of carbonic acid in the venous blood. In the 

 capillary vessels, oxygen combines with carbon ; it is cer- 

 tainly here that this combination takes place ; and since we 

 find that the volume of carbonic acid expired is smaller than 

 that of the oxygen which has disappeared in respiration, we 

 must admit that not only the carbon, but even the hydro- 

 gen, which made part of the organic elements of the blood 

 and the tissues, combines with the oxygen to form water. 

 Here, then, is another instance of combustion besides that 

 of carbon. 



The acetates, the tartrates, and the oxalates, which enter 

 in a state of solution into the blood, escape by the urinary 

 passages in the form of carbonates. Benzoic acid intro- 

 duced into the circulation escapes in the condition of hip- 

 puric acid also through these passages. I may also men- 

 tion that, in conjunction with Professor Piria, I introduced 

 into the circulating blood of a living animal a solution of 

 salicine. After some time we discovered in the urine a 

 substance derived from salicine, and which had the pro- 

 perty of forming a violet precipitate on the addition of a 

 salt of iron. 



