68 MICROBES, FERMENTS, AND MOULDS. 



caproic acids, under the influence of nitrogenous 

 substances and of the air; the change into glucose 

 of gums, of starch, of dextrine, of sucrose, and mannite; 

 the transformation of these substances into each other 

 under the influence of living agents, or of those 

 belonging to a living organism; the transformation 

 of such glucosides as populin, salicin, tannin, etc., 

 into sugar, or into neutral or acid substances; all 

 these phenomena are fermentations (A. Gautier). 



We may even go further. The germination of 

 seeds and the ripening of fruit are accompanied by 

 phenomena qf the same order. In animals, gastric, 

 pancreatic, and intestinal digestion, together with other 

 changes connected with nutrition and assimilation 

 which take place in the blood and in all the organs, 

 may be considered as true fermentations. In this case 

 the cells of our tissues and the blood-corpuscles play 

 the part of yeast in effecting alcoholic fermentations. 



Finally, the miasmatic, virulent, and contagious 

 diseases, which we shall study in another chapter, 

 are also caused by changes in the blood and in the 

 other fluids of the system, and should be considered 

 as fermentations, produced by minute microscopic 

 organisms analogous to ferments, and which are, as 

 we shall presently show, bacteria or microbes, strictly 

 so-called. The putrefaction of dead bodies is also 

 a fermentation. 



We shall, in this place, only consider the fermen- 

 tations which are used in manufactures. 



