556 MUSCLES. 



through a glycogen-free liver, while, on the contrary, blood poor in sugar 

 led to only a very inconsiderable formation of lactic acid. The investi- 

 gations of A. R. MANDEL and LUSK 1 also indicate a formation of lactic 

 acid from carbohydrates, in the animal body. They have shown that 

 in dogs, after phosphorus poisoning, an abundance of lactic acid occurs 

 in the blood and urine, and that this disappears from these fluids on bring- 

 ing about a phlorhizin diabetes in the animal. Phosphorus intoxication 

 caused no lactic-acid formation in a phlorhizin-diabetic dog. Although 

 it is difficult to give a satibfactory explanation of the results of these 

 experiments, still it seems probable that by elimination of the sugar in 

 phlorhizin diabetes a mother-substance of the lactic acid is lost. 



The carbohydrates, as well as the proteins, it seems, must be con- 

 sidered as the material from which the lactic acid is formed in the body. 

 In a previous chapter (VIII) we mentioned the formation of lactic acid 

 in the animal body by a deamination of alanine, and this gives us an 

 indication of a lactic-acid formation from protein. Phosphocarnic acid 

 is considered by SIEGFRIED as another source of sarcolactic acid. 



The lactic acids are amorphous. They have the appearance of color- 

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

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

 most of them also in alcohol. The two acids are differentiated from each 

 other by their different optical properties paralactic acid being dex- 

 trogyrate, while fermentation lactic acid is optically inactive also by 

 their different solubilities and the different amounts of water of crystalliza- 

 tion of the calcium and zinc salts. The zinc salt of fermentation lactic 

 acid dissolves in 58-63 parts of water at 14-15 C., and contains 18.18 

 per cent water of crystallization, corresponding to the formula Zn(C 3 H 5 O3)2 

 + 3H 2 O. The zinc salt of paralatic acid dissolves in 17.5 parts of water 

 at the above temperature and contains ordinarily 12.9 per cent water, 

 corresponding to the formula Zn(C 3 H 5 O3)2 + 2H20. The calcium salt 

 of fermentation lactic acid dissolves in 9.5 parts water and contains 

 29.22 per cent ( = 5 molecules) water of crystallization, while calcium 

 paralactate dissolves in 12.4 parts water and contains 24.83 or 26.21 

 per cent ( = 4 or 4J molecules) water of crystallization. Both calcium 

 salts crystallize, not unlike tyrosine, in spears or tufts of very fine micro- 

 scopic needles. HOPPE-SEYLER and ARAKI, who have closely studied 

 the optical properties of the lactic acids and lactates, consider the lithium 

 salt as best suited for the preparation and quantitative estimation of 

 the lactic acids. The lithium salt contains 7.29 per cent Li. For fur- 

 ther information as to the salts and specific rotation of the lactic acids 

 see' HOPPE-SEYLER-THIERFELDER'S Handbuch, 8. Aufl., 1909. 2 



1 Amer. Journ. of Physiol., 1(>. 



2 See also E. Jungfleisch, Compt. rend., 139, 140, and 142. 



