ACTION Of THE EXZYMES. 109 



This equation is entirely analogous to the one given on page 

 107. As in the case of ethyl acetate and water, we have here 

 also a reaction which can take place in either direction. No 

 matter from which side we begin, the final result is always the 

 same the presence in the reaction mixture of maltose and 

 water side by side with two molecules of dextrose. The only 

 difference between the reaction discussed on page 107 and this 

 one is that the analysis or synthesis of maltose occurs under 

 the influence of a catalyzer. But, as has been pointed out, a 

 catalyzer only alters the rate of a chemical reaction and does 

 not enter into the reaction itself (unless it does so tempora- 

 rily). The analysis or synthesis of maltose would occur in the 

 same way, and the state of equilibrium finally attained be the 

 same, even if no maltase were present, only under such cir- 

 cumstances the velocity of the reaction would be very low. 

 The system 



Maltose -f Water <=* Dextrose -1- Dextrose 



is in equilibrium under the conditions existing in HILL'S experi- 

 ments when some 85 percent of dextrose exists beside about 15 

 percent of maltose. It is clear that such a mixture of the two 

 sugars in water will undergo no apparent change whether mal- 

 tase be present or not. As shown above, however, the reaction 

 has not ceased, only the chemical change in the one direction 

 just counterbalances that in the opposite, so that outwardly 

 everything remains the same. But what must occur if into 

 the above reaction mixture some maltose or some dextrose is 

 introduced, or either of these substances is removed? It is 

 clear that this must disturb the chemical equilibrium existing 

 between the maltose on the one hand and the dextrose on the 

 other. Whenever this occurs the activity of maltase as an 

 agent hastening the establishment of a state of equilibrium 

 between these two substances must come into play, and must 

 either analyze or synthesize maltose until such a state of 

 equilibrium is again established. The introduction of dex- 



