PYOGENIC BACTERIA, 379 
Ulcerative endocarditis has been shown by the researches of 
numerous bacteriologists to be occasionally accompanied by a mycotic 
invasion of the affected tissues by the golden staphylococcus ; in 
other cases Streptococcus pyogenes is present. The researches of 
Weichselbaum, and of E. Frankel and Sanger, also show that it is 
present in a certain proportion of the cases, at least, of endocarditis 
verrucosa, although in smaller numbers. That the diseased condi- 
tion of the cardiac valves in ulcerative endocarditis is due to mycotic 
invasion is now generally admitted and is supported by experimental 
evidence. Rosenbach first (1873) produced an endocarditis in lower 
animals by mechanical injury to the cardiac valves, effected by in- 
troducing a sound through the aorta. Following his method, Wys- 
sokowitsch (1885), after injuring the cardiac valves in rabbits, in- 
jected into the circulation pure cultures of various bacteria. He 
obtained positive results with Staphylococcus aureus and Strepto- 
coccus pyogenes only. When these micrococci were injected into 
the trachea or subcutaneously the result was negative, as was the 
case when very few cocci were injected into a vein, or when two 
days or more were allowed to elapse after injury to the cardiac 
valves. Subsequently Weichselbaum, Prudden, and Frankel and 
Sanger obtained confirmatory results, thus establishing the fact that 
when the valves are first injured mechanically (or chemically— 
Prudden) 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 with- 
out previous injury to the valves by injecting into a vein the staphy- 
lococcus from a potato culture suspended in water. In his experi- 
ments not only the micrococci from the surface but the superficial 
layer of the potato was 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. In these experiments the mitral and 
tricuspid valves were affected, while the semilunar valves remained 
intact. In ulcerative endocarditis it is evident that cocci detached 
from the diseased valves must find their way into the circula- 
tion, As a matter of fact, masses of micrococci are carried away by 
the blood stream and form emboli in various parts of the body, which 
become secondary foci of infection and give rise to local necrotic 
changes and accumulations of pus. While this undoubtedly occurs, 
it is generally admitted that the mycotic infection of the cardiac 
‘valves is usually a secondary affection, resulting from the transpor- 
tation of micrococci in the blood current from some other infected 
focus. But there is no general development of micrococci in the cir- 
