ANIMAL OXIDATIONS. 7 



atoms set free on the decomposition of the water unite with the neu- 

 tral oxygen, forming hydrogen peroxide, which may naturally also 

 have an oxidizing action. 



According to the generally accepted view, which is based upon the 

 work of BACH, MANCHOT, ENGLER and collaborators, 1 the oxygen acts 

 also in the autooxidation in the first place as an entirely inactive mole- 

 cule. According to ENGLER and his collaborators, at least in the 

 simplest cases (" direct autooxidation " according to ENGLER), the 

 oxygen molecules unite with the activating body (A), forming a peroxide- 

 like substance which can give up one of the two oxygen atoms to an 

 acceptor (B) : 



= AO 2 and A 



The appearance of a peroxide has, at least in certain cases, been shown, as, 

 for instance, with dimethylfulvene C 8 Hj where the peroxide C 8 H 10 4 occurs 

 (Engler). The autooxidation may also in other cases proceed otherwise, as 

 shown by Manchot 2 in the oxidation of hydro-compounds like oxanthranol, 

 which proceeds according to the equation AH 2 + O 2 = A + H 2 O 2 , namely, with 

 the formation of a hydroperoxide. This is different from TRAUBE'S views. 



If thL is so, still we do not know to what extent &uch peroxides are 

 formed in oxidation in the living cell. The possibility of a produc- 

 tion of peroxides, and also of hydrogen peroxide, in animal oxidation 

 is still generally admitted, and CHODAT and BACH 3 have indeed been 

 able to show a peroxide formation in plants. Still, if hydrogen peroxide 

 were formed in such oxidations it would have no further physiological 

 importance, according to LOEW, because the animal and plant cells 

 contain special enzymes, called by him catalases, which quickly decom- 

 pose the hydrogen peroxide with the production of molecular oxgyen. 

 According to LOEW 4 the physiological importance of the catalases is 

 to protect the cell from hydrogen peroxide, which acts as a protoplasmic 

 poison, a view which is accepted by many investigators but still dis- 

 puted by others. 



1 Engler and Wild, Ber. d. d. chem. Gesellsch., 30; Bach, Le Moniteur scientifique, 

 1897, and Compt. rend., 124; Manchot, 1. c. 



2 Verhandl. d. Phys. med. Gesellsch. zu Wurzburg (N. F.), Bd. 39. 



3 Ber. d. d. chem. Gesell., 35 u. 36. 



4 Loew, U. S. Dept. of Agriculture, Rep. 68, 1901, and Ber. d. d. chem. Gesellsch., 

 35; in regard to the opposed views see Chodat and Bach., 1. c., Bach, Monit. scientif. 

 (4) 20; Kastle and Loevenhart, Amer. Chem. Jour., 29; Herlitzka, Chem. Centralbl., 

 1908; Euler, Hofmeister's Beitrage, 7, and especially O. Loew, Centralbl. f. Bacteriol., 

 21; Abt. 2, which contains the literature. 



