STREPTOCOCCUS PYOGENES 145 



diseases it is often the cause of death. Many of the symptoms 

 of phthisis are due to the toxins of the streptococcus; cavity for- 

 mation and hectic fever for example. Its virulence can be in- 

 tensified by passing it through a series of animals, until, finally, 

 M>ooo cu. mm. kills in one day all the mice injected with this 

 dose. The toxin contains a peculiar haemolytic substance, which, 

 as before remarked, dissolves red cells of the blood, hence the 

 anaemia in septicaemia and in suppuration. The toxin of the 

 streptococcus, if injected under the skin, causes redness like ery- 

 sipelas. Coley's fluid containing this toxin is used to treat 

 sarcomata, since infection with the streptococcus has been known 

 to cause a disappearance of these tumors. Practically all animals 

 are susceptible to the streptococcus. 



Agglutinations. The serum from an animal injected with strep- 

 tococci, or immunized against it, will agglutinate streptococci. 



Anti-toxic sera have been prepared by injecting horses with 

 highly virulent living culture of streptococci. The serum protects 

 to a limited degree, and has some curative properties. Cultures 

 of cocci from human sources have been found to produce the 

 best toxins; there are, however, many strains. 



The foregoing description represents the principal characters of 

 the most important member of a large group of closely related 

 streptococci. Distinctions in the group are based upon the 

 solution of red blood cells, the fermentation of lactose, of maltose, 

 of salicin and the coagulation of milk. The relative value of 

 each of the members is not yet settled but investigations have 

 enabled laboratory workers to elaborate certain techniques 

 which may be expected to clear up the matter. The varieties 

 now recognized are Str. hemolyticus, epidemicus, anginosus, 

 fecalis, salivarius, equinus, and mitis. Some of these organisms 

 produce no hemolysis; they come under the term non-hemolyticus 

 and are of importance in certain respiratory and allied diseases. 

 There is a group of organisms, a sort of connecting link with 

 pneumococci, which produce green colonies on blood agar and 

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