CASUAL URINARY CONSTITUENTS. 773 



interest from this standpoint; but the changes which certain organic 

 substances undergo when introduced into the animal body may be studied 

 by the transformation products as found in the urine. 



The bodies belonging to the fatty series undergo, though not without 

 exceptions, a combustion leading toward the final products of metab- 

 olism; still, often a greater or smaller part of the bodies in question 

 escape oxidation and appear unchanged in the urine. A part of the acids 

 belonging to this series, which are otherwise decomposed into water and 

 carbonates, and render the urine neutral or alkaline, may act in this manner. 

 The volatile fatty acids poor in carbon are less easily oxidized than those 

 rich in carbon, and they therefore pass unchanged into the urine in 

 large amounts. This is especially true of formic and acetic acids 

 (SCHOTTEN, GREHANT and QUINQUAUD 1 ). In birds, according to GAGLIO 

 and GIUNTI, oxalic acid is not oxidized. Opinions on the behavior of 

 oxalic acid in mammalia and man, are conflicting; the investigations 

 of SALKOWSKI and especially of HILDEBRANDT and DAKIN 2 show 

 that oxalic acid, when introduced in medium amounts, is in part 

 oxidized in the animal body. Racemic acid, d-l tartaric acid, passes 

 (in dogs) in part into the urine, and this unburned part is optically inactive 

 according to NEUBERG and SANEYOSHI. The statement of BraoN 3 

 that Z-tartaric acid is more readily burned than d-tartaric acid is accord- 

 ingly incorrect, and the d-/-tartaric acid therefore does not belong to 

 those substances which are asymmetrically attacked in the animal 

 body. Malic acid and citric acid belong to those acids which are in great 

 part burned in the body. 4 



The destruction of normal fatty acids with several membered chains 

 takes place, our belief being based upon the work of KNOOP and DAKIN 5 

 especially, in an oxidation in the /3-position, i.e.', in the group which is in 

 the /3-position to the carboxyl group at the end. The conversion into an 



1 Schotten, Zeitschr. f. physiol. Chem., 7; Grehant and Quinquaud, Compt. Rend., 

 104. 



2 Gaglio, Arch. f. exp. Path. u. Pharm., 22; Giunti, Chem. Centralbl., 1897, 2; 

 Marfori, Maly's Jahresber., 20 and 27; Pohl, Arch. f. exp. Path. u. Pharm., 37; Sal- 

 kowski, Berl. klin. Wochenschr., 1900; Pierallini, Virchow's Arch., 160; Stradomsky, 

 ibid. ,163; Klemperer and Tritschler, Zeitschr. f. klin. Med., 44; Hildebrandt, Zeitschr. 

 f. physiol. Chem., 35; Dakin, Journ. of biol. Chem., 3. 



3 Biron, Zeitachr. f. physiol. Chem., 25; Neuberg and Saneyoshi, Bioch. Zeitschr., 

 36. O 



4 Pohl, Arch. f. exp. Path. u. Pharm., 37, which also contains reports on the inter- 

 mediary products formed in the oxidation of the fatty bodies; K. Ohta, Bioch. 

 Zeitschr., 44. 



5 F. Knoop, Hofmeister's Beitrage, 6 and Habilit.-Schrift, Freiburg, 1904; Dakin, 

 Journ. of biol. Chem., 4, 5/6 and 9. 



