97 



Gelatin stab at 20 C. In 48 hours, beginning liquefaction; in 72 

 hours liquefaction infundibuliform, slight precipitate. 



Carbohydrates. In standard extract broth to which has been added 

 one percent of the following carbohydrates, acid and gas are formed: (1) 

 glucose, (2) laevulose, (3) raffinose, (4) maltose, (5) sucrose, (6) lactose, 

 (7) inulin, (8) starch, (9) glycerol, (10) mannitol. No acid or gas and 

 little growth in dulcite broth, which remains clear and limpid. In other 

 broths gas usually appear in 24 hours. Media uniformly clouded, slight 

 stringy precipitate, no pellicle. Media 48 hours, slightly viscous. 



Clark and Lubs. Typical reaction of 'Grain' type coli, in 48 hours 

 at 37 C., i. e. reaction alkaline to methyl red, Voges-Proskauer test posi- 

 tive. 



Indol production in 1 percent peptone, four days at 37 C. No 

 indol detected when tested for by the nitrite and by Ehrlich's p ar a- dimethyl - 

 amido-benzaldehyde method. 



Glucose-neutral-red broth. Same reaction as Bact. coli i. e. yellow 

 fluorescence with gas formation. 



Litmus milk at 37 C. In 24 hours acid, in 48 hours partially 

 reduced, coagulated with extrusion of whey; beginning digestion of curd. 



Lactose bile at 37 C. In 96 hours, no gas or growth. 



Chromogenesis. None. 



Ewing, in 1919, reported a similar bacillus in the water supply of 

 Baltimore and noted that its presence was associated with heavy rainfall. 



TABLE LIV. ELIMINATON OF SPURIOUS PRESUMPTIVE TESTS. 

 (After Hall and Ellefson 1918) 



Inhibition of Growth of Spore Formers. Hall has suggested the 

 use of gentian violet in the lactose broth presumptive test tube to eliminate 

 spurious presumptive tests. In a series of examinations with water and 

 pure cultures, he found that 1-20,000 to 1-100,000 gentian violet in lactose 

 broth exerted but little inhibitory influence on the growth of Bact. coli; 

 whereas the anaerobes were almost completely checked. 



Table LIV. shows the marked inhibitory action of gentian violet on 

 the anaerobes. Not only are spurious presumptive tests eliminated but 

 the total of successful isolations of colon bacilli is increased. This 



