QUALITATIVE BACTERIOLOGICAL ANALYSIS. 193 



that of the B. typhosus ; the medium, however, acquired a 

 greenish tinge at the surface. In an agar-stab the same greenish 

 tint was seen in the medium ; on an agar-slope the growth was 

 thin and greyish in tint, the discrete colonies were small. In 

 gelatine plates the colonies grew slowly : those in the depth 

 were circular in shape, of yellowish-brown colour, and coarsely 

 granular in the centre; on the surface, the colonies showed a 

 wavv irregular margin and a dark centre, from which ridges and 

 valleys ran out to the periphery. The colonies in the depth 

 resembled B. coli ; those on the surface, however, were more like 

 the B. typhosus, both in slowness of growth and the small size 

 and appearance of the colonies. A growth took place after 

 twenty-four hours in both of Proskauer and Capaldi's media ; in 

 No. I. the reaction was alkaline, and in No. II. neutral. A 

 twenty-four hours agar growth was tested as to agglutination with 

 anti-typhoid serum ; the reaction was incomplete when the 

 serum was diluted 1-100. The same serum diluted 11000 

 completely agglutinated a stock culture of B. typhosus. 



It will be noticed that this culture failed to give the cha- 

 racteristic alkaline reaction in litmus- whey. <jrermano and 

 Maurea also found that the formation of alkali by Petruschky's 

 bacillus was inconstant. The B. fyecalis alkaligenes appears to 

 be fairly common in faeces, so it is important to distinguish the 

 organism from the B. typhosus. The diagnosis can be readily 

 made, in the absence of the formation of alkali, by the brown 

 growth on potato and the absence of reaction to a highly 

 dilute anti-typhoid serum. 



The B. Enteritidis, isolated by Gartner from cases of meat 

 poisoning, seems to be intermediate between the B. coli com- 

 munis and the B. typhosus. In gelatine plates the surface 

 colonies sometimes exactly resemble those of B. typhosus, at 

 other times the wavy margin and ridge and valley appearance 

 are not marked ; the colonies then appear coarsely granular 

 with a nearly circular outline. The colonies grow more quickly 

 than those of the B. typhosus, but more slowly than those of 

 B. coli. In gelatine-stab and streak the growths resemble those 

 of B. typhosus, but are more copious. In glticose-agar-stab at 

 37 C. gas is always produced, but in giucose-gelatine-shake at 

 22 G. it is sometimes absent. Gas does not appear 



