CHAPTER XXXIV 

 Fermentation 



437. Insoluble Ferments. Fermentation is a chemical 

 change produced by a class of bodies called ferments. Insol- 

 uble or organized ferments are single celled, microscopic 

 plants which have a definite structure. Many of them 

 are bacteria while others are low forms of plant life. 

 Nearly all secrete definite chemical products capable of 

 producing fermentation. The insoluble or organized fer- 

 ments are composed mainly of nitrogenous compounds 

 but also contain non-nitrogenous and mineral matter. 

 Some, as the tubercular organism, contain cellulose. 



438. Soluble Ferments or Enzymes. Enzymes are 

 organic compounds, secreted by cells, and have the 

 property of producing chemical changes. They are also 

 called soluble ferments, chemical ferments, and diastases. 

 There are a great many different kinds of soluble ferments 

 some of which, as diastase and maltase, are capable of 

 acting upon carbohydrates, while others, as pepsin and 

 pancreatin, act upon proteid bodies. Enzymes produce 

 chemical change without entering into the composition 

 of the substance or giving up any of their own material 

 to the reacting compounds. A small amount of diastase 

 will change a large amount of starch to soluble forms 

 without losing its power of action. The enzymes are all 

 soluble in water and are precipitated with strong alcohol. 

 Their action is not generally retarded by antiseptics and 

 chemicals which are capable of destroying organized fer- 



