192 BACTERIOLOGICAL EXAMINATION OF WATER. 



ProsTcauer and Capaldi, No. I. Growth, but no change in 

 the reaction. 



Proskauer and Capaldi, No. II. Growth, but medium rendered 

 slightly alkaline. 



Microscopical Characters. A small, highly motile bacillus, 

 closely resembling the B. typhosus. 



Staining Reactions. Stains with basic aniline dyes ; decolor- 

 ised by Gram's method. 



Reaction with Anti-typhoid Serum. Practically complete 

 agglutination with anti-typhoid serum, diluted 1-80. 



This micro-organism closely resembled the B. typhosus in 

 many of its reactions, but it did not give the typical reactions 

 in Proskauer and Capaldi's media and the anti-typhoid serum 

 which, when diluted 12,000,000, caused complete agglutination 

 of the true B. typhosus, had no complete agglutinating action 

 on the B. typhosus simulans when diluted above 1-80. 



The B. Fsecalis Alkaligenes, isolated by Petruschky, is said 

 to resemble the B. typhosus in the following points: (1) 

 Active motility ; () number of flagella ; (3) decolorisation bv 

 Gram ; (4) appearance of the colonies on gelatine plates ; (5) 

 growth in milk without fermentation ; (6) growth in sugar 

 media without the production of gas ; (7) agglutination with 

 anti-typhoid serum ; (8) failure to produce indol. It is, how- 

 ever, supposed to be distinguished by producing a brown growth 

 on potato, and rendering litmus-whey alkaline after forty-eight 

 hours incubation. 



A pure culture of this organism was obtained from Krai's 

 laboratory and carefully studied. It was a small motile bacillus, 

 closely resembling the B. typhosus. It did not stain with 

 Gram. In broth a surface pellicle was produced, which fell to 

 the foot on shaking the tube. In glucose-agar at 37 C., and in 

 lactose- and glucose-gelatine shake cultures at 22 C., there was 

 no formation of gas. Indol was not formed in Witte's peptone 

 and salt-solution after seven days incubation at 37 C. Litmus- 

 whey showed no appreciable change in reaction after seven days 

 incubation at 37 C. On potato a yellowish-brown growth was 

 produced. Milk was unchanged after seven days incubation. 

 In gelatine-stab the growth was slow, and strongly resembled 



