286 SCIENCE PROGRESS 



In certain cases synthetic actions of this kind have already 

 been observed. I may refer to the production of ethyl butyrate 

 by the action of lipase on butyric acid and ethyl alcohol in 

 the experiments of Kastle and Loevenhart, of amygdalin from 

 glucose and mandelic-nitrile-glucoside by the maltase of yeast 

 (Emmerling), of salicin by emulsin, and probably of saccharose 

 by invertase from their respective products of hydrolysis 

 (Visser), of a disaccharide from glucose by maltase (Croft Hill), 

 and of isolactose from galactose and glucose by lactase (Emil 

 Fischer and Frankland Armstrong). There is some evidence 

 also of a similar action in the case of the enzymes which act 

 upon proteins. 



We may take it, then, that, so far as investigated from this 

 point of view, enzymes have shown themselves to be capable 

 of accelerating both of the opposing components in reversible 

 reactions. 



There are, at the same time, certain cases which need a 

 little more consideration ; but before proceeding further it will 

 simplify matters if a few words be said as to the terminology of 

 the subject. It was suggested by Duclaux that the termination 

 " -ase " should be taken as expressing an enzyme, and that this 

 termination should be added to the body acted on by the 

 enzyme — e.g. lactase is the enzyme hydrolysing lactose. It is, 

 of course, inconvenient to displace some of the old-established 

 names, such as "pepsin" and "trypsin," but, as far as possible, 

 Duclaux's recommendation should be acted upon. Again, an 

 English name for the substance split by the enzyme is badly 

 wanted. " Substrate " is used by the Germans, and, in default 

 of a better, it will be used in the present article. " Hydrolyte " 

 is used by some authors ; but this name does not include cases 

 where the action is not one of hydrolysis but of intra-molecular 

 splitting or oxidation. 



It has been the custom to speak of an enzyme which attacks 

 starch or protein, for example, as " amylolytic " or " proteolytic " 

 respectively; but, as Prof. Armstrong has pointed out, these 

 names are incorrectly formed. " Amylolytic," in analogy 

 with " electrolytic," should mean a decomposition by means of 

 starch, and, to avoid this confusion, Prof. Armstrong advises 

 the use of the termination " -clastic " instead of " -lytic " in 

 speaking of enzyme action. 



After this digression I now return to the discussion of some 



