332 BACTERIA PATHOGENIC TO MAN 



from two to nine days. The most characteristic pathological lesions are 

 found in the kidneys, which contain numerous small collections of pus, 

 and under the microscope present the appearances resulting fromembolic 

 nephritis. Punctiform, whitish-yellow masses of the size of a pea are 

 found permeating the pyramids. Many of the capillaries and some of 

 the smaller arteries of the cortex are plugged up with thrombi, consisting 

 of micrococci. Metastatic abscesses may also be observed in the joints 

 and muscles. The micrococci may be recovered in pure cultures from 

 the blood and the various organs; but they are not numerous in the 

 blood and are often difficult to demonstrate microscopically. Intra- 

 venous inoculations of animals are followed by similar pathological 

 changes. Orth and Wyssokowitsch first pointed out that injection of 

 staphylococci into the circulation of rabbits whose cardiac valves have 

 previously been injured produced ulcerative endocarditis. Subsequently, 

 Weichselbaum, Prudden,and Fraenkel and Sanger obtained confirmatory 

 results, thus establishing the fact that when the valves are first injured, 

 mechanically or chemically, the injection into a vein of a pure culture of 

 staphylococcus aureus gives rise to a genuine ulcerative endocarditis. It 

 has been further shown by Ribbert that the same result may be obtained 

 without previous injury to the.valves by injecting into a vein the staphylo- 

 coccus from a potato culture suspended in water. In his experiments 

 not only the micrococci from the surface but the superficial layer of the 

 potato were scraped off with a sterilized knife and mixed with distilled 

 water, and the successful result is ascribed to the fact that the little 

 agglomerations of micrococci and infected fragments of potato attach 

 themselves to the margins of the valves more readily than isolated cocci 

 would do. Not infrequently, also, in intravenous inoculations of young 

 animals there occurs a localization of the injected material in the marrow 

 of the small bones. This may take place in full-grown animals when 

 the bones have been injured or fractured. The experimental osteo- 

 myelitis thus produced has been demonstrated to be anatomically analo- 

 gous to this disease in man. With regard to the lesions found in the 

 kidneys after intraperitoneal or intravenous inoculation of cultures of 

 the staphylococcus, it has been found that when injected in considerable 

 quantities the organism may be obtained in cultures from the urine, 

 but not sooner than six or eight hours after the injection, and not until 

 the formation of purulent foci in the kidneys has already occurred. 



Toxic SUBSTANCES. Filtrates of cultures contain very toxic sub- 

 stances. Injected into the peritoneal cavity they excite peritonitis. 

 Under the skin they produce infiltration or abscess. In the blood 

 they injure both the red and white corpuscles. 



Cultures of the staphylococcus, when sterilized by boiling and in- 

 jected subcutaneously, produce marked positive chemotaxis and often 

 local abscesses. Leber found also that sterilized cultures introduced 

 into the anterior chamber of the rabbit's eye would bring about a fibro- 

 purulent inflammation, the cornea becoming infiltrated, and perforation 

 alongside of the sclerotic ring finally taking place. This was followed 

 by the formation of pus in the anterior chamber and recovery. These 



