154 STREPTOCOCCIC INFECTION 



theory and at that time impossible to demonstrate. Pasteur undoubt- 

 edly in some of his early work saw pus organisms, but the credit of 

 identifying and describing them belongs to Ogston, who found that 

 some are spherical bodies arranged in chains while others are clustered 

 like grapes in a bunch. The former he designated streptococci and the 

 latter staphylococci. 



The Organism. Streptococci are spherical or oval bodies, from 

 0.5 to 1.5 of a micron in diameter, arranged in chains of variable length. 

 Some strains show only short, and others only long, chains. Some 

 investigators regard these as different species, while others consider 

 them as only varieties. It seems most reasonable to look on the 

 streptococci as a great family with many subfamilies, and these may 

 show marked differences in form, in cultural characteristics, and in 

 virulence. All are non-motile and sporeless. Inasmuch as these organ- 

 isms induce suppuration, they are often designated as Streptococci 

 pyogenes, to which we may add longus or brevis, as the case may be. 

 Some authors divide them according to the tenacity with which they 

 cling together or the amount of mucus formed, thus providing a type 

 known as 5. mucosus. In the animal body the chains are generally 

 short, often being reduced to diplococci. In artificial cultures the 

 chains are often long and coiled in groups forming felt-like masses. 

 Cultures rich in peptone (as high as 5 per cent.) give the most 

 abundant growths. The presence of grape-sugar (from 0.2 to 2 per 

 cent.) favors growth, but the development of too much acid may prove 

 detrimental. Blood serum, either alone or in bouillon, is an excellent 

 medium, and strains obtained from man grow best on human serum, 

 and the same holds good for other species. The streptococcus does not 

 grow abundantly on ordinary solid media. The optimum temper- 

 ature is that of the animal body, but growth proceeds slowly at as low 

 as 15 and as high as 42 C. The streptococcus is a facultative anaerobe, 

 but different strains show wide variations under diverse air supply. 

 In general, however, in the presence of air this organism loses in both 

 viability and virulence. Different strains act differently on carbo- 

 hydrates and attempts at classification have been made on this basis, 

 but have led to no practical results. These are varieties which decom- 

 pose lactose and coagulate milk. A striking action is the hemolytic effect 



