BACILLUS PYOCYANEVS. 307 



the needle, and may last from ten minutes to half an 

 hour. This is the " chameleon plienomenon " of Paul 

 Ernst. 



In bouillon the green color appears, and the growth 

 is seen in the form of delicate flooculi. A very delicate 

 mycoderma is also produced. As growth progresses, 

 the bouillon becomes darker and darker in color, until 

 it finally is about comparable in this respect with crude 

 petroleum ; at the same time it assumes a peculiar ropi- 

 ness, and very old cultures (four to six weeks in the 

 incubator) may attain about the consistency of egg- 

 albumin. 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 

 coagulation of the casein. 



On blood-serum and egg-albumin its growth is ac- 

 companied by liquefaction. The growth on coagulated 

 egg-albumin 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 dis- 

 coloration. 



In peptone solution (double strength) it causes a 

 bluish-green color. In one of four cultures from differ- 

 ent sources we observed the production of a distinct 

 blue color. 



It produces indol. 



