48 THE STORY OF GERM LIFE. 



the smell arising from a bit of decaying meat. 

 Others have peculiar tastes, as may be realized 

 in the gamy taste of meat which is in the incipi- 

 ent stages of putrefaction. By purely empirical 

 means mankind has learned methods of encourag- 

 ing the development of some of these products, and 

 is to-day making practical use of this power, pos- 

 sessed by bacteria, of furnishing desired chemical 

 compounds. Industries involving the investment 

 of hundreds of millions of dollars are founded 

 upon the products of bacterial life, and they have 

 a far more important relation to our everyday 

 life than is commonly imagined. In many cases 

 the artisan who is dependent upon this action of 

 microscopic life is unaware of the fact. His 

 processes are those which experience has taught 

 produce desired results, but, nevertheless, his 

 dependence upon bacteria is none the less funda- 

 mental. 



BACTERIA IN THE FERMENTATIVE INDUSTRIES. 



We may notice, first, several miscellaneous in- 

 stances of the application of bacteria to various 

 fermentative industries where their aid is of more 

 or less value to man. In some of the examples 

 to be mentioned the influence of bacteria is pro- 

 found and fundamental, while in others it is only 

 incidental. The fermentative industries of civili- 

 zation are gigantic in extent, and have come to 

 be an important factor in modern civilized life. 

 The large part of the fermentation is based upon 

 the growth of a class of microscopic plants which 

 we call yeasts. Bacteria and yeasts are both 

 microscopic plants, and perhaps somewhat close- 

 ly related to each other. The botanist finds a 



