206 INFLAMMATION AND SUPPURATION 



chains occur in fluid media. On the surface of agar it produces a thin, 

 semi-transparent layer with smooth margins, and there is not the 

 tendency to form separate colonies which is shown by most streptococci. 

 In a corresponding way it forms a diffuse turbidity in bouillon, with the 

 formation after a time of a somewhat glairy deposit"; sometimes there is 

 a scum on the surface. It flourishes well at a lower temperature than 

 that at which the streptococcus pyogenes will grow, and has great 

 longevity in cultures. When first isolated, some strains have been found 

 to prefer anaerobic conditions. It has very active fermentative properties 

 and coagulates milk ; probably it is the same variety as the streptococcus 

 fsecalis described above. It is non-haemolytic and relatively non- virulent, 

 in fact most strains can be injected in large doses without pathogenic 

 effects. It is a normal inhabitant of the intestine, and has been found 

 to appear in the intestine of the infant shortly after birth. The lesions 

 in which it is found are chiefly those where infection can be traced from 

 the bowel. It is practically always present in contaminated gun-shot 

 wounds at an early stage (vide p. 441), gradually disappearing at a later 

 stage. It has been found in abscesses following typhoid, and not 

 infrequently in the bladder during or after bowel infections, though also 

 apart from these. It has been obtained during the war from the blood 

 and bladder in a fair proportion of cases of septicaemic type, in others 

 where myalgia was the chief feature, in others again of the type of 

 ' ' trench fever. " ( Houston and McCloy. ) 



Toxins of Pyococci.- — As stated above, many streptococci have 

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

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

 haemolysin 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 haemolysin is reached in about eighteen hours, and 

 thereafter a diminution occurs. The hemolysin 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 heemolysin cannot be obtained. Strepto- 

 coccus viridans, though producing little or no lysis, has the 

 property of forming methsemoglobin from haemoglobin. The 

 staphylococcus aureus and staphylococcus albus also produce 

 hemolysins, which so far as can be judged by their properties 

 are identical. (The staphylococcus epidermidis albus, however, 

 produces no hemolysin.) The staphylolysin, which can readily 

 be obtained by filtration, though more stable than the strepto- 

 lysin, is also destroyed at a temperature of 55° C. It, however, 

 differs from the latter, inasmuch as an antitoxin can readily be 



