326 TEXT-BOOK OF BACTEEIOLOQY. 



the micro-organisms entered, or the quantity absorbed or, finally, 

 the varying susceptibility of the individuals stricken, will of course 

 frequently decide the result. 



Be this as it may, we believe these bacteria to be the specific ex- 

 citers of suppuration, and suppuration to be a specific reaction of the 

 tissue to the presence and activity of these bacteria. Here, as well 

 as in other cases, the pathological changes and their general sequels 

 are due to bacterial excretions — toxines and toxalbumins (among 

 them especially some albuminous substances difficult to dissolve). 



As to the waj' in which the staphylococci invade the organism 

 under natural conditions, a suitable portal is often furnished by 

 small lesions, scratches, etc. Experiments of Garre and others 

 even proved that these cocci do not require any such open passage, 

 since they were seen to penetrate the uninjured skin. No particular 

 tendency to harbor the infectious matter need be assumed in view 

 of the extraordinary diffusion of the staphylococci ; UUmann, for 

 instance, having shown that they are almost regularly met with in 

 the healthy body, the saliva, pharynx, on the skin, also in the water, 

 air, in the dust of rooms, etc. 



XXI. STAPHYLOCOCCUS PYOGENES ALBU8. 



The Staphylococcus pyog. aureus is the species of bacteria most 

 frequently occurring in pus of various origin, it having been ob- 

 served in about 80^ of all cases examined. But it is often found 

 together with other micro-organisms. The latter have become 

 better known through the researches of Eosenbach and Passet; 

 their properties prove them to be likewise causative of infiamma- 

 tory processes terminating in suppuration. 



One of them, the Staphylococcus pyogenes albus, altogether re- 

 sembles the aureus above described, being distinguished from it 

 merely by the absence of the yellow coloring matter. 



It is less common than the aureus and appears to be (as the ex- 

 periments of transmission would prove), somewhat less virulent, it 

 giving rise less readily bo severe consequences. 



XXII. STAPHYLOCOCCUS PYOGENES CITREU8. 



Passet has demonstrated in two cases a third species, the Staph, 

 pyog. citreus, which is distinguished by its beautiful lemon-yellow 

 pigment and which liquefies gelatin more slowly than aureus and 

 albus, with which it fully agrees in all other respects. 



