ITS INCIDENTAL CONSTITUENTS. 413 



This admirable and simple mode of explanation, which har- 

 monizes with the established views of the decomposition of organic 

 substances, derives considerable support both from the chemical 

 analysis of concretions as well as from medical experience, however 

 widely it may deviate from the ordinary opinions of physicians who 

 adhere to the idea of lactic, uric, and phosphatic diatheses. In the 

 mean time it would be extremely difficult to prove that uric acid 

 concretions owed their existence solely to a modification of the 

 vesical mucus ; for, as we have already observed, in speaking of 

 sedimentary formations, there must be some controlling cause in 

 the composition of the renal secretion, which in one case may 

 facilitate and in another hinder the formation of concretions. 

 There remain, probably, many other points which require to be in- 

 vestigated before we can explain all the phenomena relating to the 

 formation of concretions, or hope to arrive at a scientific interpre- 

 tation of the different forms of development of urinary calculi. 



We will now proceed to the consideration of those urinary 

 constituents which are conveyed to the body from without, and 

 which, after remaining only a short time within it, pass into the 

 urine, either wholly unchanged or in a slightly modified form. 

 This subject, which is of the highest importance in the study of 

 the metamorphosis of animal matter, was long since investigated 

 by Wohler.* and more recently by the same observer in con- 

 junction with Frerichs.f Although it may appear somewhat illo- 

 gical to notice the substances which, according to the experiments 

 made in relation to this subject, do not pass into the urine, the 

 present seems a fitting place to collect those facts which may serve 

 as a positive basis for a theory of the formation of the urine, and 

 aid in elucidating the internal mechanism of the zoo-chemical me- 

 tamorphosis of matter. 



It may be assumed as a general proposition, that such sub- 

 stances (not belonging to the nutrient matters) as are easily 

 soluble in water, and exhibit no tendency to enter into insoluble 

 combinations with the organic, or inorganic matters of the animal 

 body, alone pass into the urine. On this account, most of the 

 soluble alkaline salts, as nitrate of potash, borax, iodide of potas- 

 sium, bromide of sodium, alkaline silicates, chlorates, carbonates, 

 &c., are found unchanged in the urine. But in order that sub- 

 stances should pass unchanged into the urine, it is necessary that, 



* Zeitschr. f. Physiol. Bd. 1, S. 305328. 

 t Ann. d. Ch. u. Pharm. Bd. 65, S. 335349. 







