This change differs in principle from that assumed by Baeyer, inasmuch as the second stage is not effected by the re-addition of water, but by the keto-enol transformation, which is now usually ascribed to the migration of the hydrogen atom, although the same result can theoretically be arrived at by the addition and removal of the elements of water. The analogy of this process to what might be supposed to occur in the conversion of sugar into carbon dioxide and alcohol was pointed out by Wohl and Oesterlin, and subsequently Wohl developed a theoretical scheme of reactions by which the process of alcoholic fermentation could be represented. In the first place the elements of water are removed from the α and β carbon atoms of glucose (I) and the resulting enol (II) undergoes conversion into the corresponding ketone (III), which has the constitution of a condensation product of methylglyoxal and glyceraldehyde, and hence is readily resolved by hydrolysis into these compounds (IV). The glyceraldehyde passes by a similar series of changes (V, VI) into methylglyoxal, and this is then converted by addition of water into lactic acid (VII), a reaction which is common to all ketoaldehydes of this kind. Finally, the lactic acid is split up into alcohol and carbon dioxide (VIII):-- CHO CHO CHO │ │ │ CH(OH) H C(OH) CO │ minus · ║ │ CH(OH) OH CH ⇌ CH{2} │ │ │ CH(OH) CH(OH) CH(OH) │ │ │ CH(OH) CH(OH) CH(OH) │ │ │ CH{2}(OH) CH{2}(OH) CH{2}(OH) I. II. III. Glucose. Methylglyoxal CHO COOH CO{2} │ │ ------ CO + H{2}O CH(OH) CH{2}OH │ │ │ CH{3} CH{3} CH{3} ─────────────────────────────────────────────────────────── CHO CHO CHO COOH CO{2} │ H │ │ │ ------ CH(OH) minus · C(OH) ⇌ CO + H{2}O CH(OH) CH{2}OH │ OH ║ │ │ │ CH{2}(OH) CH{2} CH{3} CH{3} CH{3} IV. V. VI. VII. VIII. Glyceraldehyde. Methyl- Lactic Alcohol glyoxal. acid. and carbon dioxide. [p102]