THE STAPHYLOCOCCUS GROUP 261 



has been definitely established by the experiments of Carre 1 and Engels, 2 

 both of whom rubbed virulent cultures of these organisms upon their 

 skin, producing there typical furuncles. 



Animals. Rabbits are the best of the laboratory animals for 

 experimental inoculation. Subcutaneous inoculations of virulent 

 strains frequently result in abscess formation and the development of 

 a febrile reaction. These abscesses commonly ulcerate, discharge and 

 heal spontaneously. By no means do all virulent strains induce lesions, 

 however; there is great difference between them in this respect. Intra- 

 peritoneal injections frequently cause a rapidly fatal peritonitis with 

 or without septicemia. The intravenous injection of 0.25 to 1 c.c. 

 of an eighteen-hour broth culture usually causes a generalized pyemia 

 with septic foci, particularly frequent in the kidneys and liver. Orth 3 

 and Wyssokowitsch 4 have shown that mechanical injury to the heart 

 valves prior to the intravenous injection of staphylococci usually 

 causes a localization of the organisms there, producing an endocarditis. 

 If a bone is injured prior to an intravenous injection, a typical osteo- 

 myelitis frequently results. It should be remembered that the pus 

 produced by staphylococci in rabbits is more dry than that produced 

 in man. Guinea-pigs are less susceptible than rabbits to infection 

 with the staphylococcus. 



Immunity and Immunization. Staphylococci do not ordinarily 

 exhibit invasive powers for man or animals; they are usually parasitic. 

 Whenever the continuity of the skin is destroyed, as by abrasion, or 

 weakened, as in diabetes, the organisms reach the underlying tissues 

 and induce inflammatory reactions. Repeated injections first of 

 killed then live staphylococci will frequently raise the threshold of 

 infection in experimental animals to a very considerable degree, but 

 the process of immunization can not be always relied upon many 

 animals die rather abruptly with rather extensive amyloid degenera- 

 tion, particularly of the kidneys. Leukocytes, particularly the poly- 

 morphonuclear leukocytes, appear to play a prominent part in the 

 immunity against staphylococci; it can be shown by experiment that 

 the leukocytes are more active phagocytically in immunized than in 

 non-immunized animals. 



Similarly, the resistance to staphylococcus infection, which appears 



1 Fortschritt d. Med., 1885, 170. 



2 Cent. f. Bakt., Orig., 1903, xxxiv, 96. 



3 Cent. f. d. med. Wissensch., 1905, No. 33. 



4 Virchow's Arch., 1886, ciii. 



