and fermenting gain in value up to a certain point, after 

 which oxidation actually diminishes their value. Fermenting 

 in manure heaps should proceed only for about 4 months 

 after which the manure will rather lose than gain in value, 

 and as for urine the fresher it is used the more valuable it is 

 as manure, as the fermentation, caused by micrococcus ureae 

 converts the urea into Ammonium carbonate which is highly 

 volatile. To prevent fermentation, urine is kept in vats 

 for some time before use, if it is necessary to do so, by 

 mixing with it an antiseptic substance, such as sulphate of 

 iron. 



1,313. Though the uppermost layers of soils teem with 

 microbes, there are scarcely any microbes below a depth of 

 3 feet from the surface. Nitrification going on more freely 

 at the surface, nitrebeds are made only with the superficial 

 layers of soil and not with soil dug out from a deep pit. It is 

 not certain if the nitrification which results in the formation 

 of saltpetre is the result chiefly of the action of one microbe 

 or the joint result of that of several microbes. Van Tieghem 

 regards Micrococcus nitrificans which is a very small and 

 delicate micrococcus, as the determining agent, while Duclaux 

 attributes the result to the joint action of several microbes. 

 Another, microbe which has a wide influence in decomposing 

 decayed vegetable matter by destroying the cellulose of 

 vegetable cells is the Bacillus Amylobacter of Van Tieghen. 

 It is a drum-stick shaped anaerobic microbe and is the active 

 agent in the retting of jute &c. Probably nutrition of rumi- 

 nant animals which are able to digest a large proportion of 

 cellulose, is partly due to this microbe. This microbe is also 

 one of the active agents in the production of butyric acid in 

 cheese, hay, silage &c. The commonest microbe of putrefying 

 vegetable matter is the Bacterium Termo. It can be always 

 obtained by rotting some pulse in water; while rotting hay 

 shows Bacillus subtilis more abundantly. Bacillus subtilis, 

 Bacterium Termo, Bacterium Amylobacter and Micrococcus- 

 RRRR 



