174 BACTERIOLOGICAL AND ENZYME CHEMISTRY 



1. The velocity of the reaction was not proportional to the 

 amount of ester present. 



2. The velocity of the reaction was nearly proportional to 

 the concentration of the enzyme. 



3. The reaction in general did not attain completion ; 

 only when a large quantity of enzyme was present in proportion 

 to the ester was the decomposition of the latter nearly 

 complete. 



4. The coefficient of velocity of the reaction, that is, the 

 ratio of decomposed ester to undecomposed ester per unit 

 of time, was not constant but decreased with the progress 

 of the reaction. 



These results indicate that the reaction belongs to the class 

 of changes known as reversible, and that there is a tendency 

 for an equilibrium to be established between the action result- 

 ing in the decomposition of the ester, and the reverse action 

 tending to combination of the free acid and alcohol. It will 

 be remembered that a similar case was met with by Croft 

 Hill when studying the decomposition of maltose, and Kastel 

 and Loevenhart have added to the number of synthetic 

 enzyme actions by effecting a synthesis of ethyl butyrate 

 by the bringing together of ethyl alcohol and butyric acid in 

 the presence of lipase. 



Secretion of Lipase by Micro-organisms.— The secretion 

 of lipase by micro-organisms can be demonstrated in a similar 

 manner to the secretion of amylase, viz., e.g., by growing 

 Aspergillus niger on a substratum of suet or butter. Moreover, 

 if a little butter' be melted in a Petri dish and allowed to 

 set and some dilute sewage be poured over it, liquefaction 

 and accompanying rancidity wiU soon be observable. These 

 reactions are of importance in connection with the treatment 

 of sewage by anaerobic processes. 



The destruction of fat under aerobic conditions is very 

 probably the work of higher organisms such as worms. 



