490 VICTOR C. MYERS 



prevent undue strain upon the body's supply of sodium, potassium, calcium 

 and magnesium. As shown by Janney(fr), if sufficient fixed alkalies or al- 

 kali-earths are administered, so that ammonia is not required for neutral- 

 izing the acids, then the ammonia excretion may be greatly reduced, 

 cr in fact almost completely disappear from the urine. On the 

 other hand, the ammonia output may be greatly increased when there is an 

 abnormal acid production, as occurs in severe diabetes. Sherman and 

 Gettler have demonstrated that the ammonia output is dependent to a 

 considerable extent upon the balance between the acid-forming and base- 

 forming elements of the foods. Increased elimination of ammonia has 

 been observed in pernicious vomiting of pregnancy, but it is important 

 to note that here the individual is essentially in a condition of inanition, 

 which itself is characterized by a relative increase in ammonia elimina- 

 tion. 



Amino-Acids. Small amounts of amino-acids normally escape deam- 

 inization and appear in the urine. They represent about 0.5 per cent 

 of the total nitrogen, and, unless specifically determined, are recorded as 

 undetermined nitrogen. In severe liver disease, i.e., yellow atrophy, 

 phosphorus poisoning, the output of amino-acids, may be increased, and 

 occasionally certain amino-acids, such as leucin and tyrosin, actually 

 crystallize out in the urine. As already noted, however, increased amino- 

 acid excretion and hepatic disturbances are not constantly associated. 

 In certain individuals the amino-acid cystin is eliminated in considerable 

 amounts. This is regarded as an anomaly of protein metabolism. 



Creatinin. Creatinin is the anhydrid of creatin. It is the second 

 largest nitrogenous constituent of urine, the daily elimination in the 

 healthy human adult ordinarily varying between 1 and 2 grams. 



H1X T CO 



CH 3 isr CH Z 



Our accurate knowledge with regard to the elimination of crcatinin 

 dates from the introduction of the Folin colorimetric method in 3904. 

 As the result of his original studies on the elimination of creatinin, Folin 

 considered the excretion of this substance from the standpoint of a new 

 theory of protein metabolism. lie was the first to point out that the 

 amount of creatinin excreted in the urine on a meat free diet is quite 

 independent of either the amount of protein in the food or of the total 

 nitrogen in the urine, the amount excreted from day to day being prac- 

 tically constant for each individual, thus pointing conclusively to its 

 endogenous origin. The constancy of this creatinin excretion has been 



