214 INFLAMMATION AND SUPPURATION 



as detailed. And lastly, there is the streptococcus conglomerate 

 (anginosus), which is specially abundant in the throat in scarlet 

 fever, though it also occurs in other acute catarrhal states. No 

 definite statement can yet be made as to the etiological relation 

 of streptococci to scarlet fever ; we can only say that streptococci 

 are almost invariably present in the fauces, and that to them 

 many of the complications of the disease are due. 



Toxins of Pyococci. As stated above, many streptococci have 

 a distinct hsemolytic action, and this is due to the production 

 of a toxin which is largely extra-cellular. The amount of 

 hsemolysin formed varies greatly in the case of different strains 

 and also according to the medium used. McLeod recommends a 

 medium composed of 20 per cent, horse serum and 80 per cent, 

 peptone bouillon with distinctly alkaline reaction, and has found 

 a Maasen filter to be specially suitable for obtaining the 

 hsemolytic filtrate. In the medium mentioned the maximum 

 formation of hsemolysin is reached in about eighteen hours, and 

 thereafter a diminution occurs. The hsemolysin is very labile, 

 being destroyed at 55 C., and rapidly deteriorating even when 

 kept in the incubator for a few hours. The filtrate has also a 

 toxic action on the tissues, producing focal necrosis especially 

 in the liver of the rabbit. It is also a noteworthy fact that an 

 antitoxin to the hsemolysin cannot be obtained. The staphylo- 

 coccus aureus and staphylococcus albus also produce haemolysins, 

 which so far as can be judged by their properties are identical. 

 (The staphylococcus albus epidermidis, however, produces no 

 hsemolysin.) The staphylolysin, which can readily be obtained 

 by filtration, though more stable than the streptolysin, is also 

 destroyed at a temperature of 55 C. It, however, differs from 

 the latter, inasmuch as an antitoxin can readily be obtained to 

 it ; in fact, in its properties it presents a close analogy to the 

 toxins of diphtheria and tetanus. The two staphylococci 

 mentioned also produce a toxin which kills leucocytes, and is 

 therefore called " leucocidin " (van de Velde). This toxin can 

 be obtained by filtration of fluid cultures, and on being injected 

 into animals leads to the formation of an antitoxin. Apparently 

 the same leucocidin is produced by the staphylococcus aureus 

 and staphylococcus albus. 



Bacillus coli communis. The microscopic and cultural characters are 

 described in the chapter on Typhoid Fever. The bacillus ladis aerogenes 

 and the bacillus pyogenes fcetidus closely resemble it ; they are either 

 varieties or closely related species. The former is distinguished by 

 producing more abundant gas formation, and by its growth on gelatin, 

 etc., being thicker and whiter than that of the bacillus coli. 



Bacillus aerogenes encapsulate sometimes invades the tissues before 



