BACILLUS COLI COM MUNIS. 



325 



relations to various suppurative and inflammatory conditions 

 are described in the chapter on Suppuration (p. 179). 

 Microscopically it has the same appearances and staining 

 reaction as the typhoid bacillus, and like the latter also 

 presents variations in size, though it is usually somewhat 

 shorter (Fig. 88). It is motile, and possesses lateral 

 flagella, which, however, are fewer in number and some- 

 what shorter than those of the typhoid bacillus. It is 

 easily isolated from 

 the stools of men and 

 animals by any of 

 the ordinary methods. 

 After, e.g., twenty- 

 four hours' incubation 

 at 37 C. on agar, 

 there are large super- 

 ficial colonies and 

 small deep colonies 

 in the plates. To 

 the naked eye they 

 are denser and more 

 glistening than those 

 of typhoid when 



FIG. 88. Bacillus coli comnmnis. Film 

 preparation from a young culture on agar. 

 Stained with weak carbol-fuchsin. x 1000. 



viewed by transmitted 

 light, and rather of 

 a brownish-white 

 colour. Under a low objective the colonies again appear 

 denser than those of the typhoid bacillus and more granular. 

 On ordinary gelatine and agar media the appearances are 

 similar to those of the typhoid bacillus, but the growth is 

 whiter, thicker, and more opaque, and gives the impres- 

 sion of having greater vigour. In the case of gelatine stab 

 cultures, a few gas bubbles sometimes develop in the 

 medium (Fig. 87, C.) On potatoes in forty-eight hours 

 there is a distinct film of growth of brownish tint and 

 moist-looking surface, which rapidly spreads and becomes 

 thicker. This contrasts very markedly with the colourless 

 film of the B. typhosus. 



