258 BACTERIOLOGICAL AND ENZYME CHEMISTRY 



loss of ammonia. Following the ammoniacal fermentation 

 will be the decomposition of albuminoids, yielding ultimately, 

 as has been shown, various amino acids. The decomposition 

 of carbohydrates, other than cellulose, which occur in dung, 

 e.g., starch, gums and possibly certain sugars, will also occur 

 with some rapidity, yielding acids capable of uniting with 

 ammonia and any other bases present ; these various decom- 

 positions take place with considerable evolution of carbon 

 dioxide. 



The fermentation of the cellulose is the longest delayed, and 

 probably takes place both anaerobically and aerobically, 

 according to the conditions obtaining in different parts of the 

 manure heap. Acids are also produced here as by-products ; 

 probably also the valuable residual humus is a product of the 

 fermentation of cellulose. 



The quantity of nitrogen in the manure will depend, as 

 already indicated, on the care taken to exclude air in the 

 manner of forming the manure heap. If the heap is well 

 pressed down, the conditions are mainly anaerobic, and the 

 heap can be kept for considerable periods without serious 

 loss of valuable constituents. 



It is sometimes necessary, e.g., for market gardening, to 

 prepare manure quickly, and large piles may not then be 

 conveniently made. In such a case a considerable quantity 

 of nitrogen passes off in the free state, apparently by direct 

 oxidation of nitrogenous matter. 



Well-rotted manure will contain all the materials for plant 

 food, and the time which has elapsed in its preparation will 

 be saved by the greater availability of its constituents when 

 it is placed on the ground. According to Warington one ton 

 of farmyard manure supplies 9 to 15 Ibs. of nitrogen, a 

 similar amount of potash, and 4 to 9 Ibs. of phosphoric 

 acid. It is thus, of course, an attenuated manure, and 

 further changes have to take place after it is incorporated 

 with the soil, before the plant can make full use of it ; the 



