PATHOGENIC BACTERIA. 



141 



Potato. A thin white layer which gradually becomes yellow 

 and gives out a doughy smell. 



Staining. Very readily colored with ordinary stains; also 

 with Gram's method. 



Pathogenesis When rabbits are injected with cultures of this 

 microbe into the knee-joint or pleura, they die in a day. If 

 injected subcutaneously, only a local action occurs, namely, 

 abscesses. 



If directly into circulation, a general phleg- 

 monous condition arises, the capillaries be- 

 come plugged with masses of cocci, infarct 

 occur in kidney and liver, and metastatic ab- 

 scesses form in viscera and joints. Garre", by 

 rubbing the culture on his forearm, caused 

 carbuncles to appear. 



Several varieties of the pyogenic staphylo- 

 cocci are recognized according to their color- 

 producing properties and slight variations of 

 growth. Of these, the staphylococcus pyog- 

 enes aureus is the most virulent, and is con- 

 sidered the type of the group. They are 

 always present on the surface of the body, 

 beneath the nails, in the nose and mouth, in 

 the dust of streets, and on the floor of houses. 



Staphylococcus pyogenes albus differs 



coccus 



aureus. 



from the preceding only in the absence of Stab culture. Micro- 



pigment and in its slight virulence. Welch 



describes a variety constantly found both on 



the skin and in its deeper layers, which he calls the staphylo- 



coccus epidermidis albus. 



Micrococcus Pyogenes Citreus. (Passett.) This liquefies gel- 

 atine less rapidly than the pyogenes aureus, and forms a citron- 

 yellow pigment instead of the orange-yellow of the aureus. 



Micrococcus Cereus Albus. (Passet.) Differs from the pyo- 

 genes albus in the form of colony. A white shiny growth like 

 drops of wax ; hence the name cereus. 



Micrococcus Cereus Flavus. (Passet.) A lemon-yellow 

 colored growth after a short time, otherwise not differing from 

 cereus albus. 



