IMMUNITY TO STAPHYLOCOCCUS. 545 



endocarditis usually is ulcerative and leads to 

 mctastatic foci of infection. Staphylococci have a 

 particular affinity for the bony tissues, especially 

 the bone marrow and the periosteum; they are the 

 most common agent in the production of osteomye- 

 litis and cause the so-called periostitis albuminosa. 

 It is thought that they may persist in bone lesions 

 for a period of years and later start up a fresh 

 process. They involve the joints less frequently, 

 but have been found, presumably as secondary 

 agents, in acute rheumatism, and as the primary 

 cause in pyemic abscesses of the joints. They are 

 found occasionally in abscesses of the mammary 

 and parotid glands, liver, lungs, and in pyorrhea Mixed 

 alveolaris (rare). The cultivation of staphylococci 

 in a pure state from the tissues does not of neces- 

 sity indicate that they are the essential organism 

 in the process (smallpox, rheumatism, etc.). Pre- 

 vious infections by many organisms, and likewise 

 traumas, predispose to localization of the staphy- 

 lococcus, and any infectious process in the skin is 

 likely to be invaded by these organisms secondarily. 



Infections with the staphylococcus are charac- Leucocytes 



TIT, TIT i i ,i * n Natural 



terized by both local and general leucocytosis, the immunity. 

 local leucocytosis being a part of the suppurative 

 process. As stated above, the staphylococcus con- 

 tains a thermostabile constituent, which exerts a 

 positive chemotatic effect on the leucocytes. Al- 

 though it is possible to consider the accumulation 

 of the leucocytes merely as the expression of this 

 affinity, it has been shown with sufficient clearness 

 that polymorphonuclear leucocytes are able to in- 

 gest living staphylococci and kill them. 3 They 



3. Phagocytosis of staphylococci was first observed by 

 Kirch in 1889. 



