262 DECOMPOSITION 



producing the decomposition, (c) the enzym by means 

 of which the organism brings about the decomposition, 

 (d) the material products, and (e) the energy changes. 

 The relation of the decomposition, whether inside or out- 

 side the body of the organism producing it, to the rest of 

 the metabolic activities of the organism should also be 

 considered. 



Alcoholic Fermentation, so-called from one of its 

 principal products — the other being CO. — is used by 

 man in raising bread, in the manufacture of fermented 

 liquors, and in the manufacture of alcohol for use in the 

 arts, as fuel, etc. Owing to its importance it has been 

 studied with great care and increasing skill. Among the 

 most important contributions to our knowledge of the 

 whole subject are those made by the eminent Frenchman, 

 Pasteur, whose studies of the so-called " diseases of wine " 

 led to definite knowledge of the processes involved in the 

 making of alcoholic liquors. In alcoholic fermentation 

 sugar is the substance acted upon. In bread dough and 

 in beerwort malt sugar is derived from starch in flour 

 and in germinating grain. The same is true of corn and 

 potato mash from which Bourbon and Irish whiskies 

 were obtained. In the must of grapes the fermentable 

 sugar, fructose, already exists. Different species of yeasts 

 are the organisms producing the decomposition. The 

 yeast used in bread-making and in beer-making is one 

 found commonly in the air and cultivated on a commer- 

 cial scale with the result that superior strains or varieties 

 of yeast are now obtainable, just as the florist furnishes 

 superior strains or varieties of roses and chrysanthemums. 

 The fermentation of wine is accomplished by means of 

 the wild yeasts found on the skins of the grapes. The 

 superior quality of wines of certain districts and of certain 

 seasons is due in part to the superiority of the local 

 varieties of yeast, though due also in part to the favorable 

 conditions at the time of wine-making, and to the supe- 

 rior substances contained in the grapes. The alcohol 



