122 MICROBES, FERMENTS, AND MOULDS. 



materials for effecting oxidation. This is another 

 instance of the part played by microbes in artificial 

 fermentation. 



Gayon and Dupetit believe that, in addition to 

 the microbes which produce nitre, there are others 

 which decompose the nitrates produced by the former. 

 When nitrate of potassium is placed in culture- 

 liquids, drain-water, chicken-broth, etc., it disappears 

 rapidly under the action of these microbes. Under 

 favourable conditions of temperature and environ- 

 ment, culture microbes daily reduce one gramme of 

 nitre to the litre. This decomposition causes the dis- 

 engagement of nitrogen, the formation of ammonia 

 and carbonic acid, which latter remain in solution in 

 the form of bicarbonate. Gayon and Dupetit believe 

 that this fact explains certain chemical phenomena 

 which occur in the soil, under the influence of manure 

 and water. 



Thus fresh discoveries show more clearly every 

 day the importance of the part played by microbes 

 in nature. Agriculture, manufactures, geology, and 

 chemistry must take them into account, since they 

 are the active agents of a number of phenomena 

 which have hitherto been obscure in physics, 

 chemistry, and physiology. 



