254 SCIENCE PROGRESS 



been isolated. 1 Neuberg considers that this reaction is induced, 

 not by zymase, but by a distinct " carboxylase" enzyme, for the 

 action of zymase can be paralysed by antiseptics and destroyed 

 by high temperatures which leave the carboxylase unaffected. 

 Yeast cells liberate C0 2 from acetic, butyric, lactic, oxalic, tar- 

 taric, and other acids; but there is no evidence to show that 

 this is due to the specific action of the carboxylase enzyme. 



Zymases inducing alcoholic fermentation have been shown 

 to exist in many vegetable organisms, not only bacteria and 

 moulds, but also in the higher plants. Stoklasa, Palladin, 2 and 

 others have demonstrated them in seeds, leaves, flowers, and roots 

 of numerous plants, and hence it seems probable that they are 

 of universal distribution. In addition to C0 2 and alcohol, lactic, 

 acetic, and formic acids are produced, apparently as intermediate 

 products in the decomposition, whilst according to Stoklasa 

 some free hydrogen is liberated. 



In animal tissues the existence of zymases is not definitely 

 proved. Stoklasa and others have brought forward evidence in 

 their favour, but the majority of investigators 3 have failed to 

 obtain positive results when the possibility of bacterial infection 

 was excluded. However, Kobert 4 found that if the yolk of 

 tortoise eggs or sea-urchin ova were ground up and incubated 

 with glucose in the presence of toluol and i per cent. NaF, 

 appreciable quantities of alcohol were formed. If Ascaris, 

 earthworms, and other invertebrate animals were ground up 

 with kieselguhr and incubated sixteen hours with toluol and NaF, 

 they likewise yielded some alcohol on incubation, so he con- 

 cludes that these organisms, and also the ova, contain zymase. 

 Still these results have not been confirmed, and even if they are 

 correct it does not necessarily follow that they hold for higher 

 animals. 



The evidence in favour of the existence of glycolytic enzymes 

 in animal tissues is somewhat stronger, though it is not above 

 suspicion. Cohnheim 5 found that if glucose were incubated with 



1 Neuberg and Karczag, Biochem. Zeit. 36, p. 68, 191 1 ; Neuberg and Rosen- 

 thal, ibid. 51, p. 128, 1 91 3 ; 61, p. 171, 1914. 



3 Cf. Vernon, Intracellular Enzymes, p. 109, 1908. 



3 Cf. Harden and Maclean, Journ. Physiol. 42, p. 64, 191 1. 



4 Kobert, Arch.f. d. ges. Physiol. 99, p. 116, 1903. 



5 Cohnheim, Zeit. f. physiol. Chem. 39, p. 336 ; 42, p. 401 ; 43, p. 547 ; 47, 

 p. 253, 1906. 



