IMPORTANCE OF FERMENTATION IN FARM LIFE. 2Q 



These discoveries led to a sharp separation of ferments into two 

 different classes. On the one hand were those which, like yeast, 

 were produced by organisms and were called organized ferments, 

 and on the other were those which contained no organisms and 

 were called unorganized ferments. These latter ferments received 

 the name of enzymes, which name is now in most common use. 



What are enzymes? Over this question there has been not a 

 little discussion. But in spite of it we know very little about them. 

 They seem to be chemical bodies, capable of producing chemical 

 changes in certain substances. But their action seems to differ 

 from chemical actions in general in that the ferment itself is ap- 

 parently not used up in the process. Whether this is strictly true 

 may, from theoretical reasons, be doubted; but at all events, no 

 direct evidence exists that they are used up, and everything indi- 

 cates that they can act indefinitely. A very small amount of an 

 enzyme may produce a very large amount of chemical change, and 

 the enzyme does not appear to enter into the new chemical bodies in 

 any degree whatever. In some respects the enzymes resemble 

 living bodies, especially in their relation to heat, and in the fact that 

 they are always produced by living organisms. But in other re- 

 spects they are sharply marked off from the organized ferments. A 

 long series of disinfectants like glycerine and alcohol, which kill 

 the organized ferments, have no influence upon the enzymes. The 

 latter do not increase by growth in the fermenting material, nor 

 does their continued action depend upon their nutrition. The 

 opposite is true of yeast and bacteria. The distinction between 

 these two classes of fermentations has been kept clearly in mind 

 in the development of our knowledge of fermentation in the last 

 half-century. 



IMPORTANCE OF FERMENTATION IN FARM LIFE. 



The value of all these types of fermentation in agriculture is 

 evident from the following list of the most important of them. In 

 the first class may be mentioned : 



The alcoholic fermentation; the butyric fermentation, which pro- 



