384 APPLICATION OF METHODS OF BACTERIOLOGY 



preparations made from cultures, it is commonly clustered 

 in irregular masses. It does not form long filaments, there 

 being rarely more than four joined end to end, and most 

 frequently occurs as single cells. 



It grows readily on all artificial media, and gives to some 

 of them a bright-green color that is most conspicuous where 

 it is in contact with the air. This green color, which becomes 

 more and more marked as growth advances, is not seen in 

 the growth itself to any extent, but is diffused through the 

 medium on which the organism is developing. Ultimately 

 this color becomes much darker, and in very old cultures 

 may become almost black (sometimes very dark blue-green, 

 at others brownish-black, at others more or less of a claret 

 red). 



NOTE. To a fresh agar culture of this organism, in 

 which the green coloration of the medium is especially 

 marked, add about 2 c.c. of chloroform. Shake gently, and 

 note that the chloroform extracts a blue coloring-matter 

 from the culture, leaving the latter more or less yellow. 



Allow the chloroform extract to stand for several days; 

 note what occurs; how do you account for it? 



Prepare a 100 c.c. Ehrlenmeyer flask with 75 c.c. of 

 sterile bouillon or peptone solution. Inoculate it with this 

 organism and allow it to stand, without shaking, in the 

 incubator at body temperature for about a week. Note 

 its condition on removal. Now agitate it thoroughly with 

 air; best by pouring it into a beaker and stirring with a 

 glass rod. Note what now occurs. Now abstract with 5 c.c. 

 of chloroform again the blue extract of "pyoscyanin" 

 is obtained. The dirty yellowish or reddish-yellow color 

 of the supernatant fluid, somewhat fluorescent, is due to 



