982 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



Methyl Amido-acetic Acid, or Sarcosin, CH 5 .NH.CH 2 .COOH. This is not found 

 in the body, but is derived from creatin, theobromin, and caffein by heating with barium 

 hydroxide. 



PROPYL COMPOUNDS. 



Normal or Primary Propyl Alcohol, CH 3 CH 2 CH 2 OH. This is one of 

 the higher alcohols formed in the fermentation of sugar, and on oxidation 

 yields propyl aldehyde and propionic acid. 



Propionic Acid, CH 3 CH 2 COOH. Combined with glycerin this forms the 

 simplest fat; salts of this acid feel fatty to the touch. Propionic acid is a 

 product of the dry distillation of sugar, of the butyric-acid fermentation of 

 milk-sugar, and of the putrefaction of proteid. It is said to be present in the 

 sweat, in the bile, and sometimes in the contents of the stomach. Like others 

 of the lower fatty acids, it may partially escape oxidation and appear in traces in 

 the urine (see p. 980). 



/3-Acetyl Propionic Acid, or Levulic Acid, CH 3 COCH 2 CH 2 COOH. This is the next 

 higher homologue to aceto-acetic acid. It has been obtained only by boiling sugars, espe- 

 cially levulose, with acid and alkalies, and since Kossel and Neumann l found that it is 

 yielded by some nucleins they conclude that this indicates the presence of the carbo- 

 hydrate radical in these nucleins. 



Dimethyl Ketone, or Acetone, CH 3 COCH 3 . This is found normally in 

 the blood and urine, and in especially large quantities in patients suffering 

 from an abnormal decomposition of organized proteid (see p. 981). During 

 the first day of starvation by Cetti, the starvation artist, the amount of acetone 

 in the urine rose to forty-eight times that of the day previous. 2 It may like- 

 wise appear in the breath, giving a characteristic odor. Acetone is a product 

 of the dry distillation of tartaric and citric acids, of wood, and of sugar. Its 

 occurrence in the urine, in diabetes, however, is not proportional in any way 

 to sugar-metabolism or non-metabolism (see p. 981). Oxidized, acetone yields 

 acetic and formic acids, whereas, treated with hydrogen, it is resolved into sec- 

 ondary propyl alcohol. When acetone is in the urine it is also found in the in- 

 testinal canal and in the feces, probably by passage through the intestinal wall. 



BUTYL COMPOUNDS. 



Normal Butyric Acid, CH 3 CH 2 CH 2 COOH. Butyric acid was first found 

 in butter, combined with glycerin. When free it gives the rancid odor to 

 butter, and likewise contributes to the odor of sweat. It has been detected in 

 the spleen, in the blood, and in the urine, but usually only in traces. As a pro- 

 duct of putrefaction of proteid, and especially of carbohydrates, it is found in 

 the intestines and in the stomach when the acidity is insufficient to be bacteri- 

 cidal. It contributes to the unpleasant taste after indigestion, through the 

 return of a small portion of the chyme to the mouth. In cheese it is a 

 product of the putrefaction of casein. 



If starch, sugar, or dextrin be treated with water, calcium carbonate, and 



1 Verhandlung der Berliner physiologischen Gesellschaft, Archivfiir Physiologic, 1894, p. 536. 

 1 Fr. Miiller : Berliner klinische Wochemchrift, 1887, p. 428. 



