o24 The Storage of Farmijard Manure 



2. Decarboxylation, i.e., the elimination of COg; - 



R R 



I I 



CHNH2 = CH2NHo + CO., 



...J 



COO in 



or, instead of COg, formic acid may be split ofE : 

 R R 



CH . NHo + H = CH2NH0 + H . COOH 



COO H Hi 



Unlike deaminisation, decarboxylation is an anaerobic process, 

 any exception being explained by assuming the presence of some 

 obligate anaerobe^. It is the characteristic feature of putrefaction: 

 the nitrogenous bases or amines produced being typical putrefaction 

 products. 



We have, therefore, this fundamental distinction : 



Under aerobic conditions the general type of action is that ammonia 

 splits off and a complex acid is left. 



Under anaerobic conditions two types of action may occur : ammonia 

 may be split off leaving a complex acid as before, or carbon dioxide 

 may be split off leaving a complex amine. 



When the aeration conditions change the products change also: 

 a molecular grouping which is stable under anaerobic conditions may 

 prove unstable as soon as air is admitted : e.g. p-hydroxy-phenyl- 

 propionic acid, which breaks down further ^ to p-cresol and phenol, 

 etc. Similarly, groupings stable under aerobic conditions, e.g. hydroxy- 

 acids, do not seem to form under anaerobic conditions. 



It is not known precisely what conditions determine whether 

 deaminisation or decarboxylation shall take place, but usually both 

 go on simultaneously, and deaminisation preponderates. But if we 

 regard the decomposition of protein as a preliminary process for the 

 nutrition of plants it would appear that deaminisation is the type of 

 decomposition at which the agriculturist should aim. The acids which 

 are simultaneously formed give rise to calcium salts which probably 

 break down to form calcium carbonate in the soil, while the ammonia is 



1 Bienstock, Archivf. Hygiene, 1899, 36, 355-89; 1901, 39, 390-427. Rettger, L. F. 

 J. Biol. Chem. 1906, 2, 71-86; 1907, 4, 45-55; and 1912, 13, 341-46. 

 * See Barger, loc. cit. p. 8. 



