872 STATE BOARD OF AGRICULTURE. 



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

 that an enzymic curve under certain conditions shows the form of a 

 fermentation curve. We can imagine that an enzyme is acting slowly 

 at first, because of an unsatisfactory acidity of the medium. By a 

 chemical or microbial process, independent of the enzymic action, the 

 acidity may be made more suitable for the enzyme, and this will cause 

 an increased rate of action of the enzyme and give the type of a fer- 

 mentation curve without the presence of organisms. The value of the 

 curves is, therefore, not an absolute one and no conclusions ought to be 

 drawn without consideration of the possibilities of error. 



CONCLUSIONS. 



If a curve of a biochemical process is plotted, taking as abscissa the 

 time elapsed and as ordinate the total amounts of compounds pro- 

 duced, the shape of this curve will in many instances indicate the nature 

 of the change taking place. In a purely chemical or enzymic change, 

 the active mass does not increase, and therefore the rapidity of the pro- 

 cess measured by the angle of elevation of the curve does not increase. 

 (An enzyme is underetood to be a chemical compound, unable to multi- 

 ply). The curve changes with the time, becoming gradually parallel 

 to the base line. If we are dealing with changes caused by micro- 

 organisms, the active mass increases as long as micro-organisms increase, 

 and consequently, the rate of the process, or the angle of elevation will 

 rise as long as the increase continues. This elevation of the curve is 

 characteristic for compounds produced by any multiplying organism. 

 From the time the increase ceases, we are dealing with a purely 

 enzymic curve. 



The exact plotting of the curve allows us to make fairly accurate 

 statements about the multiplication and the duration of the increase 

 of bacteria, even if they cannot be counted by our present methods. 

 The point of inflection of a curve shows the moment when the organisms 

 producing the substance under study reach their maximum number and 

 can be studied with greatest convenience. 



In some instances, the point of inflection is changed to a straight line, 

 indicating a strain of bacteria very resistant to their own products; 

 this seems to take place especially in poor media, as soil extracts. A 

 few experiments indicate that poorly nourished bacteria are able to 

 produce a larger amount of fennentation products than well nourished 

 bacteria though they need a much longer time to accomplish it. 



