34 MANURES FOR FRUIT TREES 



No fewer than seventeen different bacterial soil 

 fertilisers have already been discovered, and to 

 these, as a class, Nobbe has given the name of 

 " nitragin." The production of nitragin has been 

 undertaken on a large scale in Germany, and it is 

 stated that one bottle (2s. 6c?.) is sufficient for an 

 acre of land. 



The bacteria present in various soils ^ are given 

 in the following table : — 



The process of nitrification, or the conversion of 

 organic nitrogen into ammoniacal salts and the latter 



the air. This organ, which has been found on the leaves of aJl 

 plants examined, exists abundantly on highly nitrogenous plants 

 and sparsely on plants poor in nitrogen. The nitrogen- absorbing 

 organs are seen under the microscope to be short, blunt, trans- 

 versely-divided hairs directed upwards into the air. These hairs 

 are the manufactories of albumen, and were found in holly and 

 pine trees, among a large number of other plants. This is a most 

 important discovery, and well worthy of further investigation. 

 ' A. B. Griffiths, A Manual of Bacteriology, p. 277. 



