LACTIC ACIDS. 583 



in poisoning by phosphorus, and especially after extirpation of the liver 

 seems to be paralactic acid. 



The origin of paralactic acid in the animal organism has been sought 

 by several investigators, who took for basis the researches of GAGLIO, 

 MINKOWSKI, and ARAKI, in a decomposition of protein in the- tissues 

 GAGLIO claims a lactic-acid formation by passing blood through the sur- 

 viving kidneys and lungs. He also found 0.3-0.5 p. m. lactic acid in the 

 blood of a dog after protein food, and only 0.17-0.21 p. m. after fast- 

 ing for forty-eight hours. According to MINKOWSKI the quantity of lactic 

 acid eliminated by the urine in animals with extirpated livers is increased 

 with protein food, while the administration of carbohydrates has no 

 effect. ARAKI has also shown that if we produce a scarcity of oxygen 

 in animals (dogs, rabbits, and hens) by poisoning with carbon monoxide, 

 by the inhalation of air deficient in oxygen, or by any other means, a 

 considerable elimination of lactic acid (besides sugar and also often 

 albumin) takes place through the urine, an observation which has been 

 confirmed by SAITO and KATSUYAMA. 1 As a scarcity of oxygen, accord- 

 ing to the ordinary statements, produces an increase of the protein 

 catabolism in the body, the increased elimination of lactic acid in these 

 cases must be due in part to an increased protein destruction and in parti 

 to a diminished oxidation. 



ARAKI has not drawn such a conclusion from his experiments, but 

 he considers the abundant formation of lactic acid to be due to a cleavage 

 of the sugar formed from the glycogen. He found that in all cases where 

 lactic acid and sugar appeared in the urine the quantity of glycogen 

 in the liver and muscles was always diminished. Without denying 

 the possibility of a formation of lactic acid from protein, he states that 

 with lack of oxygen we have to deal with an incomplete combustion 

 of the lactic acid derived by a cleavage of the sugar. Although the 

 abundant formation of lactic acid under these circumstances can be 

 explained in different ways, still there are other conditions which make 

 the formation of lactic acid from proteins very probable. To this 

 belongs the lactic acid formation from alanine, in the liver, as mentioned 

 in a previous chapter, and recently further substantiated by EMBDEN 

 and F, KRAUS. 2 



The carbohydrates are also considered as the mother-substance 

 of the lactic acid, as it is now generally admitted that the cleavage of the 



1 Gaglio, Arch. f. (Anat. u.) Physiol., 1886; Minkowski., Arch exp. Path, u. Pharm., 

 21 and 31; Araki, Zeitschr. f. physiol. Chem., 15, 16, 17, and 19; Saito and Katsuyama, 

 ibid., 32. 



2 Neuberg and Langstein, Arch. f. (Anat. u.) Physiol. 1903; Embden and F. Kraus, 

 Bioch. Zeitschr. 45. 



