24 BACTERIA IN DAILY LIFE 



typhoid fever, and issues in response to applications 

 a simple outfit with instructions how to collect 

 specimens of blood and a form which they request 

 shall be returned filled in with all the details 

 concerning the case under observation. Only a 

 few drops of blood are required for the examina- 

 tion, and these before being despatched to the 

 State Laboratory are collected on slips of paper 

 and allowed to dry. If the addition of this sus- 

 pected blood in the proportion of one to twenty 

 to a young and vigorous culture of typhoid bacilli 

 succeeds in paralysing their movements, producing 

 the characteristic clumping together or agglutina- 

 tion of the bacilli, then the reaction is considered 

 positive and the case one of typhoid fever. 



That, however, some risk attends the placing 

 of too implicit a reliance on this method of 

 diagnosis alone is evident from the fact that a 

 negative reaction, or in other words, absence of 

 all agglutinising phenomena, is sometimes as- 

 sociated with blood throughout what is beyond 

 all question a well-defined case of typhoid fever, 

 whilst in the first week of this disease the test 

 is frequently negative in character. Rouget, who 

 has made a very careful inquiry into the value 

 to be attached to the sero-diagnosis of typhoid 

 fever, states that he has found in a large number 

 of examinations of blood derived from undoubted 



