\Miii vr. COMPOSITION, \\l> CHARACTER OP I'BIl 531 



ing the indoxyl in an a<-i<l solution by means of ferric chloride to indigo 

 blue, and shaking ou1 the indigo blue with chloroform. The depth of 

 the eolor of the chloroform affords a rough means of determining 

 the amount of indican present. The fad thai the indican tesl is m 

 live must nut be taken t" mean that the intestinal pi ormal, 



fin- if the intestine fails to contain phenylated amino acids, or tin- pr< 

 bacteria are uo1 present, no indican will be found. On the other hand, 

 the putrefactive process of the large bowel may no1 he very i jive, 

 yel the amount of indican in the urine 1m- increased, becaus - ater 



absorption due to constipation. 



skatolc, a fecal-smelling substance, is formed by certain kinds of bac- 

 teria. The greater proportion of this substance is excreted by the bowel, 

 hut it' tin- person i> constipated, some of it may find its way into the 

 blood to impart ;i fecal odor t<i the breath ami urine. I'- pi 

 therefore has some diagnostic importance. 



A very interesting body which is sometimes found in tin- urine is 

 homogentisic . /-•'',/. It is thoughl t" be an intermediate step in the metab- 

 olism of tyrosine, am) is found in the urine of people suffering from 

 alkaptonuria. The disease is remarkable in that it appears to run in 

 families ami produces no ill effects. Homogentisic acid is a str 

 reducing agent, ami fur this reason may he confused with sugar in 

 Pehling's test. 



Tin inorganic constituents of the urine include the acids: chlorides 

 sulphates ami phosphates; ami the bases: sodium, potassium, magnesium, 

 ami calcium. 



The Acids of the Urine. The chlorides compose the hulk of the acid 

 radicles in the urine. Although they appear to he necessary constituents 

 of the living cell, they do nut. so far as known, enter into combinati 

 with the organic constituents. The tissues appear to require a rather 

 definite concentration of sodium chloride in order rry on their 



work, for reduction in the sodium-chloride intake of the body results 

 in a reduction in the chloride excretion by the urine. In salt s\ 

 the chlorides may disappear entirely from the urine, the amounl 

 chloride excreted appearing t«> he closely related t>> the amount 



invested. When the intake is constant, the rat< n is like 



more or less constant, hut a sudden reduction in the salt of the diet may 

 b impanied by a slight d< in the salt content <>f the bl< 



with an attendant loss of water. On the other hand, when the salt is 



again taken, there is a retention of salt ami of water, with a c 

 increase in body weight, until equilibrium is ■ 1 on the 



level. While the above is the usual reaction, a tenl 



salt without an increase in the wati >f the bodv may occui 



