170 THE SECRETIONS: 



ments 1 and those of Lehmann, but the separation of nitrogenous 

 compounds, as for instance urea, through the urine, occurs 

 even when no food is taken. The urine is most abundant in 

 urea and sulphates after active bodily exercise, in consequence, 

 doubtless, of increased vascular excitement. The quantity of 

 urine discharged in twenty-four hours, amounts on an average to 

 about 45 ounces. It is more abundant in the prime of life than in 

 old age or childhood, and in the male than in the female sex. 



ON PATHOLOGICAL CHANGES IN THE URINE. 



During disease the urine may undergo numerous modifica- 

 tions, both in its physical characters and its chemical constitution. 

 The chemical changes may be reduced to one of the following 

 forms. 



1. One or more of the normal constituents of the urine ex- 

 isting in larger quantity than in healthy urine. 



2. One or more of the normal constituents existing in less 

 quantity than in healthy urine. 



3. A normal constituent absent. 



4. The presence of substances that do not exist in normal 

 urine. 



Qualitative and quantitative analyses of urine modified by disease. 



In tracing the changes which the urine undergoes in dis- 

 ease, the simple addition of certain tests is sometimes all that 

 is sufficient, while in other cases it is requisite to institute a 

 quantitative analysis. I shall now proceed to describe these 

 changes in accordance with the above scheme. 



INCREASE, DECREASE, OR ABSENCE OF THE NORMAL CONSTI- 

 TUENTS OF THE URINE. 



1. Increase or diminution of the solid constituents generally. 



I have already observed that the proportion of the solid con- 

 stituents to the water is so very variable, is so dependent upon 

 the vicarious action of the skin and lungs, and upon the quan- 



1 Brande's Archiv, xxii, p, 25. 



