ARTHUR ISAAC KENDALL 237 



work of Fischer upon the structure of carbohydrates, and by the discovery of hexose 

 phosphate by Harden and Young,' attention has been paid by later investigators to 

 the mechanism of sugar fermentation by yeast. The obvious complexity of the process 

 and the relative ease with which suitable amounts of yeast may be obtained have 

 together focused attention upon the fermentation activities of the Saccharomycetes 

 to the virtual exclusion of the bacteria. 



However, the products resulting from yeast fermentation have at least some quali- 

 tative resemblance to those produced by certain types of bacteria and, in the light of 

 studies made in the earlier days of bacteriology by Frankland and Frew,^ Frankland 

 and Lumsden,5 Harden,^ and more recently by the highly significant work of Neuberg 

 and his associates,^ much light has been shed upon some of the bacterial fermentations. 



The Neuberg equations. — Neuberg^ has propounded three principal types of 

 fermentation, aerogenic in character, and relating especially to yeast: 



Type I: C6Hu06 = 2CO.+ 2CH3 • CH.OH . 

 (Glucose) (Alcohol) 



This is the classical Gay-Lussac equation.^ 



Typell: aH^.Oa + Na.S03+H.O = C3H8O3 + CH3 CHO • NaHS03+NaHC03. 

 (Glucose) (Sodium sulphite) (Glycerol) (Acetaldehyde- 



sulphite compound) 



This type is given in the presence of sodium sulphide (Abfangverfahren). The sul- 

 phite protects the acetaldehyde from secondary change; the yield of carbon dioxide 

 and of alcohol is diminished and the yield of glycerol is increased. 



Type III (in the presence of alkali) is presumed to occur in three stages, as 

 follows: 



Type III: (a) C6H:.06 = CH3CHOH • COOH+CH3 • CO • COOH+H, 

 (Glucose) (Lactic acid) (Pyruvic acid) 



(b) 2CHs • CO • COOH = 2CH3 • COH+2CO. 



(Acetaldehyde) 



(c) 2CH3 • CHO+H.O = C.,H50H+CH3 • COOK 



(Alcohol) (Acetic acid) 



The completed reaction, therefore, becomes: 



2C6Hx.06+H.O=2CH3 • CHOH • COOH+C.H3OH+CH3 • COOH+2CO.+ 2H. . 



'Harden, A., and Young, W. J.: Proc. Chem. Soc, 21, 189. 1905; Proc. Roy. Soc. (Series B), 

 80, 299. 1908. 



^ Frankland, P. F., and Frew, W.: J . Chem. Soc, 61, 254. 1892. 



3 Frankland, P. F., and Lumsden, J. S.: ibid., p. 432. 1892. 



••Harden, A.: ibid., 79, 612. 1901. 



sSee especially Abderhalden, E.: Ilandb. d. biol. Arbeilsmelh., Abt. IV, pp. 565, 593, 615, 625. 

 1927; Oppenheimer, C: Handb. d. Bioch. d. Menschen u. Thiere (H. Aufl.), 2, 422. 1924. 



* Neuberg, C, and Hirsch, J.: Biocliem. Ztschr., 100, 304. 1919. 



7 Gay-Lussac, L. J.: loc. cil. 



