ITS QUANTITATIVE RELATIONS. 451 



by animal food, while they are considerably diminished by a vege- 

 table diet, and still more so by a non-nitrogenous one. 



(2.) Although the urea is a product of the effete and decom- 

 posed tissues of the animal organism., the quantity in which it 

 occurs in the urine depends in part upon the nature of the food 

 that has been taken ; during a highly nitrogenous animal diet, the 

 quantity of urea is absolutely increased, while, on a vegetable as 

 well as on a positively non-nitrogenous diet, it is absolutely dimi- 

 nished. Moreover, the relative quantity of urea, as compared with 

 the other solid constituents of the urine, increases, or diminishes, 

 with the nature of the food. During a mixed diet, I found that 

 in my own urine the ratio of the urea to the other solid constituents 

 was as 100 : 116; during an animal diet, as 100 : 63; during a 

 vegetable diet, as 100 : 156; and during a non-nitrogenous diet, 

 as 100 : 170. 



(3.) The quantity of uric acid in the urine depends much more 

 on other conditions, and possibly on other substances introduced 

 into the organism, than on any peculiarity of diet. The differences 

 observed during these observations were too small to allow of our 

 concluding that the nature of the food exerted any essential influ- 

 ence on the formation of uric acid. 



(4.) When the protein-compounds, and, consequently, the 

 nitrogen of the animal food, are absorbed in excess in the intes- 

 tinal canal, that portion of them which is not applied to the repro- 

 duction of the consumed tissues, undergoes metamorphosis, and, 

 at last, is again rapidly separated by the kidneys in the form of 

 urea and uric acid. It is only through the kidneys that the animal 

 organism gets rid of any excess of nitrogen which may be absorbed. 



(5.) The sulphates and phosphates which are discharged corre- 

 spond very nearly in quantity with the nitrogenous matter that 

 has been taken, that is to say, with the protein-compounds, which 

 contain sulphur and phosphorus ; after the almost exclusive use of 

 protein-compounds, the quantity of these salts in the urine is con- 

 siderably increased. 



(6.) It follows from these propositions, that the other organic 

 constituents of the urine, that is to say, the extractive matters, 

 must be very much diminished during an animal diet ; we find, 

 from our investigations, that after the use of vegetable food, there 

 is an absolute (not a mere relative) augmentation of such snb- 

 stances a proof that vegetable food contributes largely to the 

 formation of the extractive matters of the urine. Further, after 

 the use of animal food, the physical properties of the urine 



2 G 2 



