Isolation of Specific Pathogenes. 



79 



B. coli. 



(3) Gelatin-slope. Thick, broad, 

 grayish-white growth with a cre- 

 nated margin. 



(4) Witte's Peptone and Salt 

 Solution. Indol produced. 



(5) Milk. Coagulated. 



(6) Litmus- whey, one week at 

 37 C. Acid produced, usually 

 requiring from 20 to 40 per cent of 



^T 



alkali to neutralize it. 

 10 



(7) Neutral-red Glucose-agar. 

 Marked green fluorescence. 



(8) Glucose-gelatin and Lac- 

 tose-gelatin Shake Cultures, and 

 Glucose-agar-stab. Marked gas 

 formation. 



(9) Gelatin, 25 per cent, incu- 

 bated at 37 C.' Thick -film 

 appears on the surface. 



(10) Potato. As a rule, a thick 

 yellowish-brown growth. 



(n) Proskauer and Capaldi's 

 Media. No. I, after twenty hours 

 growth, medium acid. No. II, 

 Growth, medium neutral or faintly 

 alkaline. 



(12) Nitrate-broth. Nitrate re- 

 duced to nitrite. 



(13) Microscopical Appear- 

 ances. A small bacillus often 

 like a coccus, not motile as a rule. 



(14) Flagella. Usually i to 3, 

 short and brittle; sometimes 8 to 

 12, long and wavy. 



(15) Agglutination. As a rule, 

 no agglutination with a dilute anti- 

 typhoid serum. 



B. typhi. 



(3) Thin, narrow, grayish-white 

 growth, crenated margin not 

 marked as in B. coli. 



(4) No formation of indol. 



(5) Unchanged after a month. 



(6) Very small amount of acid 

 produced, requiring not more than 



N 



6 per cent of alkali to neutral- 

 10 



ize it. 



(7) No change. 



(8) No gas formation. 



(9) No film appears on the sur- 

 face, but a general growth takes 

 place throughout the tube. 



(10) Thin transparent growth 

 hardly visible to the naked eye. 



(n) No. I, no growth or change 

 in the reaction of the medium. 

 No. II, Growth, medium acid. 



(12) Reduction of nitrate not so 

 marked. 



(13) Usually longer than B. 

 coli; highly motile, with a quick 

 serpent-like movement. 



(14) Usually 8 to 12, long and 

 wavy. 



(15) Marked agglutination with 

 dilute anti-typhoid serum. 



Of the many observers who have reported the isola- 

 tion of the typhoid bacillus from water, all but the most 

 recent are quite discredited, on account of the insufficiency 

 of their confirmatory tests; and even the latest results 



