12 



B. typhosus is distinguished from other coli-like microbes 

 of the coli-typhoid group (all of which fail to liquefy gelatine 

 and are gram negative in staining) are these: (a) Morpho- 

 logical : motile, cylindrical bacilli, multiflagellated, the thin, 

 long, wavy flagella distributed over the whole body; the 

 bacilli in culture are capable of forming shorter or longer 

 threads ; like other coli-bacilli they grow well at all tempera- 

 tures up to 38 or 40 C. (&) Cultural : on gelatine colonies 

 angular discs, with thicker centre, filmy margin, finely granu- 

 lar ; on gelatine streak translucent, filmy, dry-looking band, 

 slightly thicker in centre, irregular margin ; in ordinary, as also 

 in sugar gelatine shake culture, no gas formation, colonies 

 uniformly distributed throughout the gelatine ; grows always 

 slower than B. coli ; on agar not characteristic, except that 

 the growth is slower and more translucent than that of most 

 B. coli; in litmus milk acid production, slower than that 

 of most B. coli, milk remains fluid ; in phenol broth good 

 growth, no gas formation ; in ordinary broth rapid growth 

 and uniform turbidity, no indol formation ; in neutral red 

 broth no change of colour ; on potato colourless, filrny growth ; 

 on potato gelatine colonies smaller round and more trans- 

 lucent than those of most B. coli ; on potato agar and in urine 

 gelatine grows more filamentous than B. coli ; in Proskauer 

 and Capaldi medium I negative, in Proskauer and Capaldi 

 medium II positive B. coli gives the reverse test; on 

 Drigalski-Conradi medium the colonies are characteristically 

 bluish in laterally reflected light, violet-blue in directly 

 reflected light; translucent, filmy, violet margin, thicker 

 more or less acuminated centre, finely granular ; the bacilli 

 composing the colonies are oval to cylindrical, motile; in 

 MacConkey fluid (litmus glucose taurocholate of soda, pep- 

 tone) acid formation but no gas ; in litmus lactose peptone 

 growth, litmus becomes bleached, no acid or alkali, no gas ; 

 blood serum of typhoid patients (Widal's test), or blood 

 serum of an animal previously injected (prepared) with 

 typhoid culture, acting on broth culture, or emulsion of gela- 

 tine or agar culture of B. typhosus, the bacilli become arrested 

 in their motility and agglutinated into large more or less 



