96 



HICiH TEMPERATURE ORGANISM OP FERMEXTIXG TAX-BARK, 



sodium hydrate was then added, but this had no effect. Upon investigating the 

 matter it was found that Usehinsky's sohitiou did not serve as a medium for 

 gi-owing the bacterium, and its inability to feed the organism could not be 



l5 OAVS. 



Text-fig. 4. The Fermentation of Stack-bark. Daily yields of Carbon dioxide. 

 Unbroken line = test, broken line = control. 



traced to any one constituent. It had previously been found that a solution 

 similar to Uschinsky's, but containing 1 % of dextrose and 0.3 % of potassium 

 citrate, promoted the growth so that the presence of citrate or a soluble source 

 of carbon is essential. 



Meanwhile another fermentation test had l>ecn started with 25 c.c. of a 

 modified Uschinsky's solution* and 4 grams of cotton wdol tliat had been dis- 

 integrated by heating at 160° to 200°, until it could be rubbed into a line powder. 



No gas was given off in two days, so 5 c.c. of a 3 ^c solution of potassium 

 citrate was added. 



The citrate did not alter matters, for during the following two days, no 

 gas was given off. This showed that in the earlier experiment, the growtli and 

 gas production depended, not on the citrate, but on the sugar. 



So far the bacterium seenu'd incapable of attacking cellulose, but befoi-e 

 closing the experiment it was tliought advisable to see if, after a start had been 

 made with extract of bark, the bacterium would attack tlie disintegrated cotton. 

 Accordingly an extract was made by steaming 200 grams of alley-bark with 

 400 c.c. of water for an hour and filtering the extract, lirst through paper, tlicn 

 throiigh porcelain. Ten c.c. of this were added to the test; the old control was 

 thrown out and another prepared having everything the same as the test, 

 excepting the 4 gi-ams of cotton. 



* Asparagin 0.5 %, sodium chloride 0.3 %, magnesium sulphate cryst. 

 0.2 %, and monopotassium phosphate 0.2 %. 



