59 



multiplication of bacteria. In ten days the odor of 

 vanillin had entirely disappeared though it was still 

 present in the check flasks. At the end of two weeks an 

 ether extract, evaporated to dryness, showed vanillin 

 to have disappeared' from the inoculated flasks, but to 

 be present in the checks. 



After the solution had become cloudy, as is described 

 above, it was plated out and five isolations of bacteria 

 were made. These all seemed to be the same organ- 

 ism. Using the medium given above it was found that 

 this organism could rapidly cause the disappearance of 

 the vanillin. Since the vanillin was the only source of 

 carbon in the solution it is evident that the organism 

 used it as a food. 



Ciimarin. The same procedure was followed in the 

 search for organisms responsible for the disappear- 

 ance of cumarin. The solution used was the same as 

 that given for vanillin and contained cumarin at a 

 concentration of about 500 parts per million substituted 

 for vanillin. Again the cloudy appearance of the me- 

 dium showed a rapid multiplication of organisms and 

 the cumarin disappeared. The solution was plated 

 out and six isolations were made, three of which used 

 cumarin as a source of carbon. These three appeared 

 to be identical organisms as far as could be judged 

 from their growth on agar. It is understood, however, 

 that this simple criterion is not sufficient to prove their 

 identity. An ether extract made four days after in- 

 oculating 50 cc. of the nutrient solution containing ap- 

 proximately 500 parts per million of cumarin with 

 one of these organisms, showed that the cumarin had 

 disappeared. The temperature of incubation was 

 about 25 to 30 degrees C. 



Pyridine. For the isolation of organisms acting on 

 pyridine a nutrient solution was prepared containing 

 pyridine as the only source of nitrogen". This solu- 

 tion was sterilized and, by means of a sterile pipette, 

 sufficient pyridine was added to make a concentration 

 of 1000 parts per million. The solution was inoculated 

 with a small amount of soil from one of the pyridine 

 treated bottles. The contents of the flask became 



Ttiis solution contained: 



K.HPO4 0.1 gm. 



MgSO. 0.05 gm. 



FeSO^ 0.001 gm. 



KCL 0.05 gm. 



C, P. dextrose 1.0 gm. 



Dist. H2O 100 cc. 



