34 Dr. G. O. Rees's additional Observations on the 



phate into the general circulation, which has not been pro- 

 duced by the respiratory act, and which will be only eliminated 

 slowly from the blood ; and thus, immediately after food, this 

 salt will be readily found in the veins as well as the arteries, 

 though not to the same amount (vide Exp. 3) ; while, on the 

 other hand, the alkaline lactate and albuminate of chyle (yield- 

 ing an excess of alkaline carbonate as the result of the incine- 

 ration of the serum of arterial blood) will be only gradually 

 converted into basic phosphate as the respiratory act proceeds. 

 This approach in character on the part of the two kinds of 

 blood may be observed after repletion, when the blood of the 

 large arterial trunks is darker than usual, and becomes sensibly 

 brightened by exposure to air. Again, in animals kept with- 

 out food, the blood drawn from the veins will be preternatu- 

 rally bright, for the reason that respiration has been long 

 carried on without access of chyle, and the alkaline phosphate 

 is affecting the venous blood as the result of respiration. 



An approach to the arterial tint has been observed by phy- 

 siologists in the venous blood of animals kept long without 

 food. The darkened colour of arterial blood, as produced by 

 repletion, I have myself remarked, and have been enabled to 

 produce a very obvious brightening by exposing it to air. 



April 28, 1847. , 



Note. — The ash obtained from the serum of venous blood 

 contains an alkaline carbonate ; but if the crassamentum be 

 incinerated with the serum, a carbonate is not necessarily 

 present, because the phosphorized fats produce phosphoric 

 acid during their combustion, and this will form a phosphate 

 with the alkali to the exclusion of carbonic acid. It was in 

 consequence probably of these conditions that Enderlin did 

 not observe an alkaline carbonate in the ashes of blood. The 

 deduction from his observations, that no albuminate or lactate 

 of an alkali exists in the blood, is erroneous. 



V. Additional Observations on the subject of the foregoing 

 Memoir. By G. Owen Rees, M.D., F.R.S. 



Guildford Street, Russell Square, 



My dear Mr. Phillips, June 8, 1848. 



THE novelty of the view which I have put forward in the 

 foregoing paper with reference to the respiratory function, 

 induces me to address these few lines to you, in order that 

 they may be published should you consider them to contain 

 matter of sufficient interest. 



