MICROCOCCUS PYOGENES. 185 



genes, but more rarely than by other varieties, as Strept. lanceolatus, 

 Strept. pyogenes, etc. : pleuritis and pericarditis, pneumonia, hepa- 



Ititis, etc. 

 (d) In diseased animal organism : Just as in man as the 

 cause of suppuration. Statements that animals have other 

 causes of suppuration than man are erroneous. It caused 

 an epidemic osteomyelitis in geese (Lucet) and a disease of 

 gudgeon (Charrin) in France. 



Experimental Observations Regarding Pathogenic 

 Effects. — There is an extraordinary variation in the dis- 

 position of different apparently identical experimental ani- 

 mals, as also in the virulence of the micro-organisms them- 

 selves. 



The disposition is greater in young, anemic and dia- 

 betic animals. The virulence of micro-organisms freshly 

 obtained from an animal or man is often considerable, but 

 sometimes even in this case it is slight. By growth upon 

 our artificial nutrient media it is sometimes rapidly 

 reduced and sometimes almost imperceptibly changed. By 

 repeated passage from animal to animal, in fatal doses, 

 the virulence is increased for the concerned species 

 (Terni), also simultaneous inoculation with other bacteria 

 (Ortolani and De Blasi) or their metabolic products (for 

 example, the Bact. vulgare) increases the virulence. In 

 the same way repeated anaerobic cultivation heightens the 

 virulence. The intensity of the liquefaction of gelatin is 

 almost, but not entirely, parallel with the pathogenic 

 property. 



With the most exalted virulence the staphylococcus 

 causes no local suppuration, but a gelatinous edema, hem- 

 orrhages in the kidneys, often inflammatory changes in 

 the cardiac valves and in the aorta. The relative suscep- 

 tibility of animals to infection with staphylococci is shown 

 in the following decreasing series : Horse, dog, man, cat- 

 tle, sheep, rabbits, guinea-pigs, mice. In the last-named 

 numerous bacteria are necessary for infection. 



Subcutaneous injections cause abscesses, but a rather large 



mber of germs (according to Herman, 50,000,000 indi- 

 viduals equal 1 c.c. of culture) from a not highly viru- 

 lent culture is required to do this in rabbits. 



