Jan. 28, 1918 



Nitrogen- A ssiviilating Bacteria 



191 



soil the number of Azotobacter showed a decrease. Apparently ammo- 

 nium nitrate is more toxic than potassium, sodium, and calcium nitrate. 

 However, the main point at issue seems fairly well established — namely, 

 that the increase in the number of Azotobacter is caused by the nitrate 

 radical and not by the combined metal. 



Table V. 



-Influence of potassiuin tiitrate on the growth of Azotobacter [strain B) in 

 sterilized soil 



Table VI. — Influence of sodium nitrate on the growth of Azotobacter {strain B) in 



sterilized soil 



27807°— IS- 



