155 



A BioMETRic Study of the Streptococci prom Milk and prom 

 THE Human Throat.* 



By C. M. HiLLiARi). 



Two luindred and forty-two pure strains of streptococci isolated from 

 milk and from the human throat liave been compared as to their morph- 

 ology, Gram stain and gentian violet reaction by the plate method, and 

 their quantitative arid production in seven carbohydrate and related or- 

 ganic media. Hemolysis was studied with 02 strains. 



We hav<' been ahlf to make no correlation between the length of 

 chain or the relation to violet stain with any other character. 



Seventeen out of 92 cultures gave hemolysis when streaked on blood 

 agar ])lates. Five of these cultures came from normal milk, five — the 

 most vigorous hemolizers — were from milk where udder trouble was indi- 

 cated in the cow, and seven were normal throat forms. 



The seven substances tested showed a definite order of availability 

 for acid production. This order ("metabolic gradient") and the per cent, 

 of cultures yielding 1.2% or more of acid when grown at 37 C for three 

 da.vs is shown in the following table : 



Gluecose (Monosaccharide) 98.0% 



Lactose (Disaccaride) 7G.0% 



Saccharose (Disaccharide) 65.5% 



Salicin (Glucoside) 42.7% 



Rafiinose (Trisaccharide) 37.5% 



Inulin (Starch) 9.0% 



.AInnnite (Ilexahydric alcohol ) 1.5% 



It will be noted that the degree of availability is closely associated 

 with the size and complexity of the substance. 



According to the positive reaction — over 1.2%. acid — in the test sub- 

 stances, 88% of the cultures may be placed in eight groups. 



The following features separate milk from throat streptococci : 

 (1) Milk organisms yield over 2.5% acid in lactose and saccharose at 

 37 C. (2) They seldom ferment a substance higher in the metabolic series 



*rull Report in Jour. Ind. Dis. Vol. XII, No. 2. 



