EXPERIMENT STATION BULLETINS. 



361 



at +6°C. without salt has a distinct poii^t of inflection, the decomposi- 

 tion of protein is caused by molds developing in that butter, while the 

 other samples show a distinct curve of enzymic or chemical change. 

 AVe must conclude from this that if the protein degradation in cold 

 storage butter is due to micro-organisms, these had reached their 

 highest number at the time the investigation began, and did not multi- 

 ply after the butter was put in storage. The conditions of the butter 

 remain practically the same after it has once reached the temperature 

 of cold storage, since the moisture in butter, especially in salted butter, 

 does not freeze. 



Another example is the nitrification in soils after addition of am- 

 monium salt. Coleman (Centralblatt fuer Bakteriologie II, Bd. 20, p. 

 408) found that the addition of dextrose increases the rapidity of nitri- 

 fication. 



NITRIFICATION IN SOIL. 



Plotting the curves from the above table, we find a typical fermentation 

 curve, proving a large increase of nitrifying bacteria. With our present 

 methods of counting nitrifying bacteria, it would have needed an ex- 



Fig. 11. Nitrification in Soil with and without Dextrose. 



