A NEW PHOSPHORESCING ORGANISM. 183 



which prolonged heating induced in the reaction of the medium. This 

 effect was easily demonstrated by submitting gelatin and agar tubes, 

 which had the optimum reaction and hence gave a marked phosphores- 

 cence to repeated or prolonged heating. The tubes which were heated 

 the most were found, on subsequent inoculation, to give the least light. 

 In such cases, as a rule, the growth was nearly as abundant as in the 

 tubes which had not been overheated; the only difference being in the 

 amount of light produced. When, however, the medium was submitted to 

 excessive heating, the resulting alteration was such as to inhibit entirely 

 the growth of the organism. 



The sterilization of the gelatin was effected by steaming for twenty 

 minutes on each of three consecutive days. The agar was sterilized in 

 like manner for thirty minutes. The use of the autoclave was avoided, 

 owing to the risk of overheating the media. 



In some experiments different amounts of magnesium sulphate, with 

 and without sodium chloride, were added, but no appreciable effect was 

 observed. The same was true of the use of asparagin. 



The phosphorescence of the cultures, especially when the medium pos- 

 sessed optimum reaction, was found to persist for many days, and at 

 times even lasted a month, although a gradual decrease in the intensity 

 of the light was observable. In the dark room the light was a delicate 

 bluish green, while in the presence of diffuse or artificial light, the 

 cultures showed an indigo blue appearance. The intensity of the light, 

 especially Avhen large tubes or Roux flasks were used, was such as to 

 enable one with ease to read the time on a watch. Good i)hotographs 

 were obtained of such cultures in the dark room by exposing them be- 

 fore the camera for one hour. 



The ])henomenou of phosphorescence resembled in many respects that 

 of pigment production. Thus the presence of air, a low temperature, 

 an alkaline reaction and darkness were favorable conditions as has 

 already been noted. 



H. X. Torre Y, B. S., 



Assistant in Bacteriology. 



From the Hygienic Laboratory, University of Michigan, 



Ann Arbor. 



