260 PHYSIOLOGICAL CHEMISTRY. 



Muscle-sugar, of which traces only occur in the living muscle 

 and which is probably formed after the death of the muscle from 

 the muscle-glycogen, is perhaps grape-sugar (glucose). As an inter- 

 mediate step in this sugar formation we must mention dextrin, 

 which is sometimes found in the muscles. Perhaps this dextrin has 

 been confounded with glycogen. 



Lactic Acids. Of the four acids of the formula C 3 H 6 3 there is 

 one, hydracrylic acid, which is not found in the animal organism. 

 The statements as to the occurrence of another, ethylen lactic 

 acid (in meat extract), are disputed. EtUidene lactic acid, 

 CH 3 . CH(OH).COOH, is of physiologico-chemical importance. 

 Two modifications occur the optically inactive FERMENTATION" 

 LACTIC ACID, and the optically active, dextro-gyrate PABALACTIC 



ACID, Or SARCOLACTIC ACID. 



The fermentation lactic acid, which is formed from milk-sugar 

 by allowing milk to sour and by the acid fermentation of other 

 carbohydrates, is considered to exist in small quantities in the 

 muscles (HEINTZ), in the gray matter of the brain (GSCHEIDLEN), 

 and in diabetic urine. During digestion this acid is also found in 

 the contents of the stomach and intestines, and as alkali lactate 

 in the chyle. The paralactic acid is, at all events, the true acid of 

 meat extracts, and this alone has been found with certainty in dead 

 muscle. That lactic acid which is found in the spleen, lymphatic 

 glands, thymus, thyroid gland, blood (traces), bile, pathological 

 transudations, osteomalicous bones, in perspiration in puerperal 

 fever, and in the urine after excessive marches, in acute yellow 

 atrophy of the liver, in poisoning by phosporus, especially after 

 extirpation of the liver (in geese, according to MINKOWSKI, in frogs 

 by MARCUSE and WERTHER), seems to be paralactic acid. 



The lactic acids are amorphous. They have the appearance of 

 colorless or faintly yellowish, acid-reacting syrups which mix in all 

 proportions with water, alcohol, or ether. The salts are soluble in. 

 water, and most of them in alcohol. The two acids are differenti- 

 ated from each other by their different optical properties paralactic 

 acid being dextro-gryate, while fermentation lactic acid is optically 

 inactive also by their different solubilities and the different 

 amounts of water of crystallization of the calcium and zinc salts. 

 The zinc salt of fermentation lactic acid dissolves in 58-63 parts of 



