INORGANIC CONSTITUENTS OF THE URINE. 215 



proportion is discharged, derived exclusively from the tissues. 

 We have already noted the fact that the products of disassim- 

 ilation of the nitrogenized principles are never discharged 

 in health without being accompanied with certain inorganic 

 salts, such as the chlorides, sulphates, and phosphates. 



In connection with the fact that phosphorus exists (in 

 precisely what condition it is not known) in the nervous 

 matter, it has been stated that mental exertion is always at- 

 tended with an increase in the elimination of phosphates ; 

 and this has been advanced to show that these salts are 

 specially derived from disassimilation of the brain-substance. 

 Experiments show that it is not alone the phosphates that are 

 increased in quantity under these conditions, but urea, the 

 chlorides, sulphates, and inorganic matters generally; 1 and 

 in point of fact, any physiological conditions which increase 

 the proportion of nitrogenized excrementitious principles in- 

 crease as well the elimination of inorganic matters. It can- 

 not be assumed, therefore, that the discharge of phosphates is 

 specially connected with the activity of the brain. We learn 

 nothing from pathology upon this point, for although numer- 

 ous observations have been made upon the excretion of 

 phosphoric acid in disease Vogel having made about one 

 thousand different analyses in various affections* no defi- 

 nite results have been obtained. 



From these facts it is seen that there is no physiological 

 reason why we are able to connect the elimination of the 

 phosphates with the disassimilation of any particular tissue 

 or organ, especially as these salts in some form are univer- 

 sally distributed in the organism. 



1 HAMMOND, Urological Contributions. American Journal of the Medical 

 Sciences, Philadelphia, 1856, Xew Series, vol. xxxi., p. 334. 



BYASSOX, Essai sur la relation qui existe d Vetat physiologique entre 



Vactivite cerebrale et la composition des urines, Paris, 1868, p. 66. By reference 

 to the table by Byasson on page 48, it will be seen that the proportion of sul- 

 phuric acid in the urine is more than doubled by mental exertion, while the 

 proportion of phosphoric acid is increased less than one-third. 



2 NEUBAUER AND VOGEL, op. tit., p. 413, et seq. 



