458 LACTIC ACID 



tent. As, moreover, introduction of alanin and inosite 

 gave no definite result, the conclusions reached were in con- 

 sonance with the important observations of Embden 14 with 

 carbohydrate-free expressed muscle juices, and those of 

 Fletcher 15 with ground muscle, that postmortem forma- 

 tion of lactic acid takes place not at the expense of carbohy- 

 drates, or of inosite or alanin, but at the expense of some 

 unknown predecessor, Embden 's "latitacidoge*," which may 

 possibly be thought of as related with the hypothetic phos- 

 phosarcous acid of Siegfried (v. Vol. I of this series, p. 148, 

 Chemistry of the Tissues). 



The observations upon muscle autolysis thus gave no 

 basis for assuming a connection between lactic acid and the 

 carbohydrates. And as no increase of lactic acid production 

 was obtained by perfusing the posterior extremities of dogs 

 with sugar added to the blood, Asher and Jackson were dis- 

 posed to accept the idea that the lactic acid does not arise 

 from carbohydrates but from the decomposition of protein. 16 



Origin of Lactic Acid from Sugar. Much more certain 

 evidence of the origin of lactic acid from carbohydrates may 

 be met, however, in the liver perfusion experiments of Emb- 

 den and his associates. 17 These indicated that in perfusing 

 a dog's liver, free of glycogen, with bovine blood no lactic 

 acid is formed de novo; although in perfusing a liver rich 

 in glycogen under similar experimental conditions there 

 could always be observed a very marked new formation of 

 S-lactic acid. A result of the same kind could be obtained, 

 although the amount of acid was somewhat less, when glucose 

 was added to the fluid used in perfusing a liver free of glyco- 

 gen. Alanin also proved to be a lactic acid former. Embden 



14 G. Embden and F. Kraus, 26 Kongr. f. innere Med., 1909, 351; G. Emb- 

 den, F. Kalberlah and H. Engel, Biochem. Zeitschr., 45, 58, 1912. 



16 W. M. Fletcher (Cambridge), Jour, of Physiol., 48, 286, 1911. 



16 L. Asher and H. C. Jackson, Zeitschr. f. Biol., 41, 393, 1901. 



"G. Embden with M. Almagia, Centralbl. f. Physiol., 18, 832, 1905; v. 

 Noorden and Embden, Centralbl. f. Stoffw., n. s., 1, 1, 1906; G. Embden and 

 F. Kraus, Biochem. Zeitschr., 45, 1, 1912. 



