PPOCEEDIXGS OF SECTION I. 585 



The scientific proof of any organism being B. typliosus is not 

 completely achieved without Pfeiffer's test, but for practical pur- 

 poses an organism giving typical reactions on the above sugars 

 and agglutinating equally with an anti-typhoid serum as does 

 the stock strain can be pronounced practically certain 

 B. tyjyhosns. 



A practical point in the examination of faeces is that in sus- 

 pected typhoid cases or carriers giving a negative result, a second 

 examination after the administration of a cholagogue purgative 

 will often give a positive result. 



One carrier examined by me showed on the first examination 

 only one colony of B. typhosus out of 60 likely colonies picked off 

 agar plates. Later a fresh examination after a cholagogue pur- 

 gative yielded nearly five times as great a typhosus non-typhosus 

 ratio. Using the above methods in the routine examination of 

 a very large number of specimens, of urine, faeces, &c., I have 

 obtained excellent results. In the Department's laboratory, how- 

 ever, much fuller biochemical tests are used, and as a result of 

 such full tests as are shown in the Table I., I have come to have 

 the greatest confidence in them as a means of separating B. 

 typhosus from its allies, even without the agglutination reaction. 



In the course of the last three years' work, in no case has 

 any organism been found giving sugar reactions completely iden- 

 tical with B. tyjjhosus, except those from sources strongly sus- 

 pected of harbouring the typhoid bacilli, and these organisms in 

 all caees fulfilled the agglutination test. Pseudotyphoid organisms 

 have been recovered on several occasions, and, curiously, always 

 in circumstances where one strongly suspected the presence of the 

 true organism; but, as will be seen in Table I., are always separable 

 biochemically from the true bacillus. In one case a slight agglu- 

 tination reaction was given, but not to anything like the same 

 degree of dilution as the stock culture gave. Although I have 

 labelled these cultures pseudotyphoid, I am aware that certain of 

 them are perhaps closer alHed to the Bacillus dysenteries of 

 Flexuer. For a further discussion of the organisms I would refer 

 to a paper by me in 1911 (4). 



Before leaving this part of the subject, the very interesting 

 method of Dean (5) calls for a brief note. If it is confirmed, it 

 seems to provide one of the quickest and simplest methods of 

 faeces examination. He makes plates from the faeces on agar, and 

 uses an extract of the growth as antigen in complement fixation 

 tests. He finds that even when the typhoid bacilli are added to 

 a plate overgrown with colon bacilli, in so small amount as one 

 loop, the reaction gives a positive result. Practical experiments 

 show that this method, controlled with ordinary cultural methods, 

 gives exceedingly accurate results. 



