QUALITATIVE BACTERIOLOGICAL ANALYSIS. 233 



B. typhosus. All the cultures, however, were found to present 

 the chief typical reactions of B. coli ; cultures 62 and 66 only 

 varied from the type by failing to produce indol. Culture 

 No. 70, however, which did not react at all with anti-typhoid 

 serum, showed considerable variations from the type; it was 

 highly motile, did not produce acid in litmus-whey, and failed 

 to give the characteristic reactions of B. coli in Proskauer and 

 Capaidi's media. 



Forty-five of the other cultures shown in Table A were also 

 examined as to the production of indol in peptone solution, acid 

 in litmus-whey, souring of milk and gas formation in sugar 

 media. Twelve of the cultures showed characteristic colonies 

 and gave gas in glucose media, but failed to produce indol, or 

 change milk, and the acid formed in litmus-whey was compara- 

 tively small, requiring only from 8 to 16 per cent, of ~ alkali 



to neutralise it. As regards the three tests usually considered 

 typical of B. coli, viz , the production of indol, the formation 

 of gas in sugar media, and the souring of milk, 64 per cent, 

 of the colonies examined gave all three reactions, 4'5 per 

 cent, failed to produce indol, 4'5 per cent, also failed 

 to sour milk, and 27 per cent, gave only one reaction, the 

 production of gas in sugar media. The results obtained by 

 the study of the eighty varieties of B. coli derived from 

 typhoid stools were then compared with those obtained by an 

 investigation of seventy cultures of B. coli obtained from the 

 stools of healthy men. The same procedure was followed as 

 before. As regards agglutination with anti-typhoid serum not 

 one of the cultures from healthy men was agglutinated by the 

 serum diluted 1-500 ; a complete reaction was only obtained 

 twice \\ith the serum diluted 1100, and a marked reaction ten 

 times with a dilution of 1-200. As regards cultural character- 

 istics 48 per cent, gave the three typical coli reactions, 52 per 

 cent, gave only two reactions, usually the souring of milk was 

 absent. The acid produced in litmus-whey required from 27 to 



47 per cent, of ^ alkali to neutralise it. There were no constant 

 cultural characteristics by which the cultures of B. coli which 

 reacted to anti-typhoid serum could be distinguished from those 

 which were completely uninfluenced by the serum. 



