BACTERIA IN THE SOIL 151 



mentioned. Some of the chief are described more or less 

 fully. We cannot, however, do more than name several of 

 the chief organisms concerned in reducing and breaking 

 down compounds. As we shall find in the bacteria of 

 nitrification, so also here, the entire process is rarely, if ever, 

 performed by one species. There is indeed a remarkable 

 division of labour, not only between decomposition bacteria 

 and denitrification bacteria, but between different species of 

 the same group. Bacillus fluorescens non-liquefaciens, My- 

 coderma urea, and some of the staphylococci break down 

 nitrates (denitrification), and also decompose other com- 



*:: .*>: 



t 



MlCROCOCCUS FROM SOIL 



pound bodies. Amongst the group of putrefactive bacteria 

 found in soil may be named B. coli, B. mycoides, B. mesen- 

 tericus, B. liquidus, B. prodigiosus, B. ramosus, B. vermicu- 

 lar is, B. liquefaciens, and many members in the great family 

 of Proteus. Some perform their function in soil, others in 

 water, and others, again, in dead animal bodies. Dr. 

 Buchanan Young, to whose researches in soil we have re- 

 ferred, has pointed out that in the upper reaches of burial 

 soil, where these bacteria are most largely present, there is 

 as a result no excess of organic carbon and nitrogen. Even 

 in the lower layers of such soil it is rapidly broken down. 



It will be observed, from a glance at the table, that the 

 chief results of decomposition and denitrification are as fol- 



