PSEUDOMONAS &RUGINOSA 367 



kept in the incubator for from seventy-two to ninety-six 

 hours. It occurs in from one to three minutes after touching 

 with the needle, and may last for from ten minutes to a half- 

 hour. This is the "chameleon phenomenon" of Paul Ernst. 



In bouillon the green color appears, and the growth is 

 seen in the form of delicate flocculi. A very delicate my co- 

 derma is also produced. As growth progresses, the bouillon 

 becomes darker and darker in color, and more or less fluores- 

 cent, until it finally is about comparable in this respect to 

 crude petroleum; at the same time it assumes a peculiar 

 ropiness, and very old cultures (four to six weeks in the incu- 

 bator) may attain about the consistency of raw egg-albumen. 

 This is due to the production of a substance closely allied, 

 chemically speaking, to mucin. Whether it is a metabolic 

 product or one resulting from the degeneration or the auto- 

 digestion, so to speak, of the bacteria, cannot now be said; 

 at all events, in cultures presenting this peculiarity very 

 few bacteria of normal appearance indeed, very few 

 bacteria at all are to be seen on microscopic examination. 



In milk it causes an acid reaction, with coincident coagula- 

 tion of the casein. 



On blood-serum and egg-albumen its growth is accom- 

 panied by liquefaction. The growth on coagulated egg- 

 albumen is seen as a dirty-gray deposit surrounded by a 

 narrow brownish zone; the remaining portion of the medium 

 is bright green in color. As the culture becomes older the 

 green may give way to a brown discoloration. 



In peptone solution it causes a bluish-green color. In 

 one of four cultures from different sources we observed the 

 production of a distinct blue color. In another specimen 

 the fluid was of a distinct wine red color, after 5 days at 

 body temperature. 



