218 INFLAMMATION AND SUPPURATION 



caemia, with death in a few hours. It has been proved by 

 Marmorek's experiments, and those of others, that the same 

 species of streptococcus may produce at one time merely a 

 passing local redness, at another a local suppuration, at another 

 a spreading erysipelatous condition, or again a general septi- 

 caemic infection, according as its virulence is artificially increased. 

 Such experiments are of extreme importance as explaining to 

 some extent the great diversity of lesions in the human subject 

 with which streptococci are associated. 



Bacillus Coli Communis. The virulence of this organism 

 also varies much, and can be increased by passage from animal 

 to animal. Injection into the serous cavities of rabbits pro- 

 duces a fibrinous inflammation which becomes purulent if the 

 animal lives sufficiently long. If, however, the virulence of the 

 organism be of a high"order, death takes place before suppura- 

 tion is established, and there is a septicsemic condition, the 

 organisms occurring in large numbers in the blood. Intravenous 

 injection of a few drops of a virulent bouillon culture usually 

 produces a rapid septicaemia with' scattered haemorrhages in 

 various organs. 



Lesions in the Human Subject. The following statement 

 may be made with regard to the occurrence of the chief organisms 

 mentioned, in the various suppurative and inflammatory con- 

 ditions in the human subject. The account is, however, by no 

 means exhaustive, as clinical bacteriology has shown that practi- 

 cally every part of the body may be the site of a lesion produced 

 by the pyogenic bacteria. It may also be noted that acute 

 catarrhal conditions of cavities or tubes are in many cases also 

 to be ascribed to their presence. 



The staphylococci are the most common causal agents in 

 localised abscesses, in pustules on the skin, in carbuncles, boils, 

 etc., in acute suppurative periostitis ; they also occur frequently 

 in catarrhs of mucous surfaces, in ulcerative endocarditis, and in 

 various pyaemic conditions. They may also be present in cases 

 of septicaemia. 



Streptococci are especially found in spreading inflammation 

 with or without suppuration; in diffuse phlegmonous and 

 erysipelatous conditions, suppurations in serous membranes and 

 in joints (Fig. 55). They also occur in acute suppurative 

 periostitis and ulcerative endocarditis. Secondary abscesses in 

 lymphatic glands and lymphangitis are also, we believe, more 

 frequently caused by streptococci than staphylococci. They also 

 produce fibrinous exudation on the mucous surfaces, leading 

 to the formation of false membrane in many of the cases of non- 



