PYOGENIC COCCI 173 



with Bacillus pyocyaneus and other fluorescent bacteria 

 are believed to be varieties. 



Crystals develop on agar cultures in a short time. 



Staining. With ordinary anilin dyes. Gram negative. 



Pathogenesis. When animals are injected with fresh cul- 

 tures in the peritoneal cavities or cellular tissues, a rapidly 

 spreading edema with general suppuration develops. The 

 bacilli are found in the viscera and blood. 



If a small quantity is injected, a local suppuration occurs, 



Fig. 84. Koch-Weeks' bacillus from conjunctival exudate at third day 

 of epidemic conjunctivitis (Boston). 



and if the animal does not'die, it then can withstand large 

 quantities. It is immune. 



The Pigment. Pyocyanin. When the pus, bandages, and 

 dressings containing the Bacillus pyocyaneus are washed in 

 chloroform, the pigment is dissolved and crystallizes from the 

 chloroform in long needles. It is soluble in acidulated water, 

 which is turned red thereby, and when neutralized, the blue 

 color returns. It has no pathogenic action. It is an aromatic 

 compound. The bacillus has no especial action on the wound, 

 and is found sometimes in perspiration of healthy persons. 



