As already mentioned the action is exerted on α-ketonic acids as a class and proceeds with great readiness with oxalacetic acid, COOH·CH{2}·CO·COOH, all the three forms of which are decomposed, with α-ketoglutaric acid, and with α-ketobutyric acid. Hydroxypyruvic acid CH{2}(OH)·CO·COOH is slowly decomposed yielding glycolaldehyde, CH{2}(OH)·CHO, and this condenses to a sugar [Neuberg and Kerb, 1912, 3; 1913, 1]. Positive results have also been obtained with diketobutyric, phenylpyruvic, p-hydroxyphenylpyruvic, phenylglyoxylic and acetonedicarboxylic acids [Neuberg and Karczag, 1911, 5]. RELATION OF CARBOXYLASE TO ALCOHOLIC FERMENTATION. With regard to the relation of carboxylase to the process of alcoholic fermentation, nothing definite is yet known. As Neuberg points out [see Neuberg and Kerb, 1913, 1] the universal presence of the enzyme in yeasts capable of producing alcoholic fermentation, and the extreme readiness with which the fermentation of pyruvic acid takes place create a [p083] strong presumption that the decomposition of pyruvic acid actually forms a stage in the process of the alcoholic fermentation of the sugars. On the other hand Ehrlich's alcoholic fermentation of the amino-acids (p. 87) provides another function for carboxylase--that of decomposing the α-ketonic acids produced by the deaminisation of the amino-acids. It must be remembered in this connection that carboxylase is not specific in its action, but catalyses the decomposition not only of pyruvic acid but also of a large number of other α-ketonic acids, including many of those which correspond to the amino-acids of proteins and are doubtless formed in the characteristic decomposition of these amino-acids by yeast. Carboxylase undoubtedly effects one stage in the production of alcohols from amino-acids, whether it is also the agent by which one stage in the alcoholic fermentation of sugar is brought about still remains to be proved.