BACILLUS TYPHOSUS. 421 



nicipal Laboratory of Philadelphia in more than 

 12,000 examinations from about 10,000 febrile con- 

 ditions, leads US to regard the culture used as one of 

 the most important factors in the test. After deciding 

 upon the most suitable culture for the reaction — and it 

 is often necessary to try a great number from various 

 sources — we have adopted the plan of daily trans- 

 planting the culture into fresh bouillon and keep- 

 ing it at a temperature rarely above 20°-22° C. The 

 bacilli grown under these circumstances are usually 

 somewhat longer than when cultivated at higher tem- 

 perature, and they exhibit a regular, gliding motility 

 that renders it more easy to follow the individual cells 

 under the microscope than when they possess the usual 

 active, darting motion. 



In the group of cases examined by us by the dry- 

 blood method, including typhoid and other febrile con- 

 ditions, there is a discrepancy between the clinical and 

 the laboratory diagnosis in from 2 to 3 per cent, of the 

 cases examined. 



In the hands of all who have carefully employed 

 the Widal reaction for the diagnosis of typhoid fever 

 the results are reported to have been almost uniformly 

 satisfactory. In the great majority of cases the reac- 

 tion is, so far as experience indicates, specific — i. e., a 

 typical reaction does not occur between typhoid serum 

 and organisms other than the typhoid bacillus, nor be- 

 tween the typhoid bacillus and serums other than those 

 of typhoid fever. There are, however, confusing reac- 

 tions — so-called pseudo-reactions — in which more or 

 less clumping of the bacilli and a diminution of motion, 

 without complete cessation, are observed. These reac- 

 tions have been seen to occur with normal blood and 



