136 Physiologie. 



change in its early stages may still be a linear function of the 

 time, since the diminution of enzyme may not at first materi- 

 ally alter the magnitude of the active System. Later, however 

 the curve will fall off from a logarithmic curve. 



Gase IV. The amount of sugar present is increased. In 

 this case it may be supposed that the magnitude of the active 

 System will increase until s + ^ attain a maximum. If the 

 amount of sugar be still further increased it may be assumed 

 that the active System at any time remains unaffected. The 

 amount of hydrolyte undergoing change in a given time 

 will thus remain constant on addition of sugar beyond a cer- 

 tain minimum, but the proportion changed will decrease as 

 concentration increases. That certain enzymes have a rever- 

 sible action has been shown by Cr oft Hill for the action of 

 maltase on maitose, and by Fischer and E. F. Armstrong- 

 ior the action of lactase and emulsin. e. Drabble (London). 



Armstrong, E. F., Studies in Enzyme Action III. The 

 influence of the Products of Change on the Rate 

 of Change conditioned by Sucroclastic Enzymes. 

 (Proc. Roy. Soc. London. July 7, 1904.) 



The author's experiments seem to establish the fact that a 

 dose relationship exists between the configuration of the hexose 

 and the enzyme in those cases in which a retarding action is 

 apparent. The only hexoses found to retard hydrolysis by a 

 given enzyme are those derived from the hexosides which 

 undergo hydrolysis under the influence of that enzyme. Emil 

 Fischer has shown that only the naturally occurring hexoses 

 — glucose, mannose, galactose, and fructose — are affected 

 by sucroclastic enzymes. The lower and higher sugars, ara- 

 binose, xylose, etc. cannot be fermented, and it is of interest to 

 note that such resistant substances as straw, and the gums 

 consist largely of pentose derivatives. 



As the author has previously explained it is necessary to 

 attribute a j'-oxide formula to glucose and rts derivatives, 

 thus: 



H OH H H 



H . C— C— C— C— C— CH-2 OH 



ÖH H / ÖH 



RO 







The effect of hydrolvsis is to remove the radicie R. and 

 replace it by H. There' is every reason to suppose that the 

 enzyme is attached along the C-chain, depending for its action 

 on the groups linked to the C-atoms, perhaps, particularly on the 

 hydroxyl groups, as testified by the following facts. Fach hexose 



