280 APPLIED PHYSIOLOGY 



is derived partly from meat in the food and partly from 

 the muscles of the body. On a diet free from meat the 

 amount of it excreted is very constant for any given 

 individual under the same conditions. Creatinin is of 

 little clinical importance, but it is interesting to note 

 that, as might be expected, the amount of it excreted is 

 greatly diminished in cases in which there is extensive 

 muscular atrophy. 



Of the inorganic constituents of the urine, the 

 sulphates are derived chiefly from the decomposition 

 of proteins in the body, and the quantity of them 

 eliminated therefore runs closely parallel to the elimina- 

 tion of nitrogen. Sulphur is met with in the urine in 

 three forms (1) as inorganic sulphates ; (2) as organic 

 or ethereal sulphates ; (3) as neutral or unoxidized 

 sulphur. The inorganic sulphates are derived almost 

 entirely from the ' exogenous ' metabolism of food- 

 protein, and their amount is therefore dependent upon 

 the nature of the diet. The organic sulphates are 

 produced partly metabolically and partly as the result 

 of the union of aromatic substances produced by in- 

 testinal putrefaction (phenol, indoxyl, skatoxyl) with 

 sulphuric acid. They are therefore only to some degree 

 an index of the extent of such putrefaction, and not an 

 absolute gauge of it, as has sometimes been assumed 

 clinically. The neutral sulphur is derived entirely from 

 the endogenous metabolism of body-protein, and is a 

 measure of its intensity. 



Of the other inorganic constituents, common salt is 

 derived entirely from the food, and provided its amount 

 in the latter be constant, the excretion of it is also con- 



