Mar. 4, igis Corn-Stover Silage 597 



Although it is true that purified enzym preparations acting under 

 favorable conditions give time curves which follow, with certain modi- 

 fications, the law of mass action, while cur\res representing bacterial 

 action take an entirely different course because of an increase in the 

 active mass with the multiplication of the organisms, we are inclined 

 to believe that Lamb has placed undue confidence in this method, 

 especially when we consider the complexity of the material studied 

 and the factors concerned. A few considerations will suffice to illustrate 

 some of the possibilities of error in such a method. In the first place 

 conditions in silage are not constant, but are undergoing continual 

 change. For example, the temperature and acidity, which are of utmost 

 significance in enzym action, increase as the fermentation progresses. 

 In view of the great increase in activity of some enzyms as the temper- 

 ature is increased, and the stimulating effect on some enzyms of an 

 increased hydrogen-ion concentration (within certain limits), it is not at 

 all impossible that these factors might so modify the course of action 

 of an enzym as to produce a curve resembling that typical of bacterial 

 action. 



Again, the phenomenon of adsorption and the action of the so-called 

 antienzyms in many cases may so suppress the activities of an enzym 

 during the early stages of the reaction as to cause it to follow a course 

 not at all characteristic of enzym action. This has been beautifully 

 illustrated by Rosenthal (11) in his work on the antitryptic action of 

 egg albumen. It was shown that the trypsin was at first suppressed, 

 but gradually regained its power and increased in activity so as to give 

 the appearance of an increase in the "active mass" as indicated by a 

 curve convex to the axis of abscissae (the typical bacterial curve). On 

 the other hand, the same trypsin preparation when acting on egg albu- 

 men which had been previously heated to destroy the antitrypsin gave 

 a time curve characteristic of enzym action. 



These illustrations will suffice to show the fallacy of such a method, 

 but the number of possibilities of error in its application to such a com- 

 plex mixture as silage might be increased almost indefinitely. That the 

 limitations of this method of studying biochemical phenomena were 

 appreciated by Rahn (10) is shown in the following paragraph from 

 his valuable paper: 



It is hardly necessary to mention that the curve of a process will be an absolute 

 means of discussion only in case of pure cultures. In natiu-al fermentations, there 

 is always the possibility that different processes taking place at the same time de- 

 stroy the regular form of the curve. A simple example would be the growth of an 

 acid-producing and an alkali-producing organism in the same liquid. It is also 

 possible that an enz;jTnic curve imder certain conditions shows the form of a fermen- 

 tation curve : We can imagine that an enzym is acting slowly at first, because of an 

 imsatisfactory acidity of the medium. By a chemical or microbial process, inde- 

 pendent of the enzymic action, the acidity may be made more suitable for the en- 

 zyme, and this will cause an increased rate of action of the enzyme and give the type 



