PROCEEDINGS OF SECTION I. 587 



Equal volumes of a well-prepared emulsion of B. ti/pJios us {made by 

 iLixing in a little saline on a well slide a loopful of growth from an 

 agar slope), and the 1-30 serum are taken up, well mixed, and a 

 small drop used to make a hanging drop preparation. The value 

 of the Widal reaction for the examination of large numbers of 

 serums is therefore to some extent impaired, and a useful accessory, 

 especially in cases of urgency, where the blood culture method is 

 not so applicable is the leucocyte count. Especially is this count 

 useful when the diagnosis of a doubtful case rests between typhoid 

 and some inflammatory condition, such as appendicitis. A leu- 

 cocyte count of 6,000 or less is considered by some almost as diag- 

 nostic in an abdominal case, suggesting typhoid as a Widal, and al- 

 though I should not quite go this far, there is no doubt that a low 

 leucocyte count is an extremely characteristic feature of typhoid 

 fever. The examination of the stools or urine, though perfectly 

 practicable by a well organized bacteriological laboratory, working 

 in conjunction with the health authorities, is not usually necessary 

 ox profitable for the jDurpose of diagnosis. 



Having diagnosed the nature of the epidemic, and having made 

 arrangements for the bacteriological diagnosis of each fresh sus- 

 picious case as it crops up, a definite understanding of the lines of 

 campaign of the research into the cause of the epidemic should be 

 laid down, and all the workers should meet and clearly be made to 

 understand what is required of them. It is the greatest possible 

 advantage that every available fact should be made use of in the 

 elucidation of the problem, and no better way can be found to do 

 this than to have not only the services of a competent bacterio- 

 logist, as before mentioned in the actual field of operations, but to 

 enlist the services of the practitioners of the district, who, if ap- 

 proached in the right manner, are only too willing to help, and 

 often possess knowledge of facts that are absolutely essential to 

 the investigation, and which are very difficult to be got directly by 

 a Government officer. 



As previously stated, if there has been a properly organized 

 case-index system kept by the health authorities, much light will 

 frequently be thrown on the probable cause of the trouble at an 

 early stage. From such an index it is easy to see, as the cases are 

 reported, whether there is any possible relationship to milk or 

 water — two very important possible means of spread. 



It is of the greatest value also when an epidemic is being es- 

 pecially investigated to have a number of printed or type-written 

 forms, which can be filled in by the practitioners concerned, and 

 which are arranged so as to bring out important points, especially 



