1278 



URINE. 



From the above it would appear, that the 

 amount of urea is always diminished by a 

 vegetable diet, while the proportion of uric 

 acid excreted is not materially affected. Leh- 

 mann ascertained also, by other experiments, 

 that the amount of lactic acid, phosphates, 

 and lactates was scarcely changed, whether 

 the subject of experiment lived on an animal, 

 or vegetable, or a mixed diet. A vegetable 

 diet was found to increase considerably the 

 daily discharge of extractive matters; while 

 far less was passed under an animal diet than 

 when either a mixed or vegetable dietjwas used. 



The following table, containing the results of 

 Lehmann on different forms of diet, as affecting 

 the daily amount of the various solid matters 

 discharged by the urine, is a very important ad- 

 dition to our knowledge of this subject : 



The gramme is equal to 15*4 grains troy. 



Severe and continued bodily exercise was 

 found by Lehmann to increase the discharge 

 of urea, lactic acid, phosphates, and sulphates. 

 He observed a diminution, however, in the 

 proportion of uric acid and extractives dis- 

 charged under the same conditions. 



Simon, simultaneously with Lehmann, as- 

 certained that the amount of urea, sulphates, 

 and phosphates excreted, is increased by 

 strong bodily exercise. Simon remarks upon 

 this result: " Further confirmation of the 

 above observation is certainly desirable. If, 

 however, we might assume it as a general 

 fact, it would be an additional argument in 

 favour of my view regarding the formation of 

 urea ; for it would then become still clearer 

 that the urea is not formed during the change 

 which occurs in the blood as a consequence 

 of peripheral nutrition, but that it is formed 

 during those processes which are dependent 

 on the respiratory and circulatory functions, 

 in which we must seek for the greater part 

 of the carbonic acid which is exhaled, and for 

 the principal source of animal heat. I refer 

 to the active metamorphosis of the blood, or 

 to the mutual action excited by the blood 

 corpuscles, the plasma, and the oxygen held 

 in solution in the blood, on each other." 



Dr. Percy has made experiments corro- 

 borative of the views of Simon. He did not, 

 however, observe any augmentation of the 

 soluble salts, viz. phosphates, sulphates, and 

 chlorides. 



In relation to this subject, Simon alludes to 

 the opinion expressed by Berzelius, that at 

 least a portion of the sulphates and phosphates 

 occurring in the urine, are derived from the 

 oxidation of phosphorus and sulphur which 

 previously existed as components of protein 

 compounds, which become changed during the 

 metamorphosis of the blood. This view I 

 hold to be especially true as respects the 

 phosphates, and would here refer the reader 

 to a paper of mine printed in the Philoso- 

 phical Magazine *, in which I showed that the 

 amount of alkaline phosphate contained in the 

 serum of arterial blood is much greater than 

 in that of venous, and that the amount of such 

 salt in venous serum can be at once increased 

 by exposing the blood corpuscles to air, and 

 consequently to the action of oxygen during 

 the coagulation of the fluid. 



I feel satisfied, indeed, from my results, that 

 one great and essential difference between 

 arterial and venous blood consists in the great 

 excess of alkaline phosphate contained in the 

 serum of the blood of the arteries as compared 

 with that of the veins. 



With respect to the quantity of chloride of 

 sodium excreted by the urine, it is subject 

 to great variation. Simon remarks, that the 

 urine in disease is sometimes deficient in salts, 

 and that this deficiency takes place at the 

 expense of the chloride of sodium. He found 

 but a trace of chloride of sodium in the urine 

 of a patient suffering from typhus. 



Dr. Bence Jones has made experiments on 



* On a Function of the Red Corpuscles of the 

 Blood, by G. Owen Rees. 



