PATHOGENIC BACTERIA. 121 



Potato. The potato is soaked with the pigment, a deep fold 

 of green occurring on the surface. 



Staining. With ordinary aniline dyes. 



Pathogenesis. When animals are injected with fresh cultures 

 in the peritoneal cavities or cellular tissues, a rapidly spreading 

 oedema with general suppuration develops. The bacilli are 

 then found in the viscera and blood. 



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

 if the animal does not die it then can withstand large quanti- 

 ties. 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 com- 

 pound. The bacillus has no especial action on the wound, and 

 is found sometimes in perspiration of healthy persons. 



Bacillus Pyocyaneus. |3. (Ernst.) A bacillus found in gray- 

 ish pus-colored bandages. 



The only especial difference between this and the above is the 

 formation of brownish-yellow pigment instead of pyocyanin. The 

 form and appearance of cultures otherwise the same. 



Micrococcus Gonorrhoea. Gonococms. (Neisser.) In 1879 

 Neisser demonstrated the presence of this 

 germ in the secretion of specific urethritis. ' IG ' ' 



Form. Cocci, somewhat triangular in 

 form, found nearly always in pairs, the base 

 of one coccus facing the base of the other, 

 and giving the appearance of a Vienna roll, 

 hence the German name Seinmel (roll)-form. 

 Four to twelve such pairs are often found 

 together. 



Properties. No movement of their ow r n. 

 Culture. On gelatine-agar or potato they Gonococci in gon- 

 do not grow, and only upon human-blood orrhoeai pus. Ani- 

 serum have they given any semblance of a 

 growth. The temperature must be between 

 33 and 37 C., and the growth occurs very slowly and sparsely. 



