THE BACILLUS PYOCYANVS. 235 



tures a peculiar phenomenon may be produced by 

 lightly touching the growth with a sterilized platinum 

 needle. This phenomenon consists in a change of color 

 from brown to green at the point touched. It is best 

 seen in cultures that have been 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 from ten minutes to half an 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 

 mycoderma is also produced. 



In milk it causes an acid reaction, with coincident 

 coagulation of the casein. 



On blood serum and egg albumin its growth is accom- 

 panied 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 discoloration. 

 In peptone solution (double strength) it causes a 

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

 ferent sources there was only a blue color produced. 

 It produces indol. 



It stains with the ordinary dyes, and its flagella may 

 be readily demonstrated by Loffler's method of staining. 

 Inoculation into animals. As a rule, cultures of this 

 organism obtained directly from the discharges of a 

 wound are capable, when introduced into animals, of 

 lighting up diseased conditions ; but cultures that are 

 kept on artificial media for a long time may in part, 

 or completely, lose this power. 



When guinea-pigs or rabbits are inoculated subcuta- 



