72 



organic matter, without thereby losing their power of growth. The nitric bacterium 

 does not oxidize ammonsalts. It is also without action on potassium rhodanate and 

 hydrochloric-hydroxylamine. It therefore does not seem to produce free acid such as 

 the nitrous bacterium. A simple method for the formation of sterile plates of silica, 

 with and without carbonate, was also described. Many preparations were demon- 

 strated. 



