156 U. S. BUREAU OF FISHERIES 



shaken cultures would seem to bear out the latter view. Apparently 

 a very low oxygen tension is unfavorable to the organisms, for there 

 is no evidence of growth either in the closed arm of a fermentation 

 tube or in a special anaerobic culture media containing reduced iron 

 and an oxidation-reduction indicator. 



The bacteria can use either ammonium sulphate or sodium nitrate 

 as a source of nitrogen. When nitrate is used, after four weeks the 

 media give no test for either nitrates or nitrites. This would indicate 

 either that denitrification was taking place or that the nitrogen of the 

 nitrate was being used to synthesize bacterial protein. There would 

 hardly seem to be enough growth to support the latter hypothesis. 

 This should be investigated for there has been reported by Gerretson 

 and also Groenwege a symbiotic relation between two organisms 

 which results in denitrification and cellulose fermentation. 



The bacteria involved in the preceding fermentation are apparently 

 not the same as those involved in the rotting of wood. Organisms 

 living at temperatures close to blood-heat, or greater, have been 

 isolated from well-rotted samples of dry wood, but as yet no organism 

 thriving best at room temperatures has been found in such material. 



It has been found that solutions of crystal violet of 1/100,000 

 concentration do not completely inhibit the growth of our culture 

 of cellulose fermenters while concentrations of 1/75,000 do. 



