382 PATHOGENIC BACTERIA. 



ating power upon bouillon cultures of its respective 

 organism. 



Loffler and Abel also prepared a colon serum which 

 exerted a like specific action upon the colon bacillus, 

 but was without effect upon the typhoid bacillus. 



The serum of immunized animals has been found to 

 destroy the motility of the typhoid bacilli in a few mo- 

 ments, and to cause them to group together. Widal 

 found that the serum of convalescents and of individuals 

 suffering from the acute disease possessed the same power, 

 and suggested that this specific action might prove a val- 

 uable adjunct in diagnosis. 



Wyatt Johnston 1 and McTaggert worked upon the 

 subject, and found that a drop of blood from a typhoid 

 patient, dried upon paper and kept for some time, when 

 moistened and brought in contact with a culture of the 

 bacilli was still potent to bring about a characteristic 

 effect. When such a preparation in the u hanging drop n 

 is watched under the microscope the typhoid bacilli are 

 found to be paralyzed in from one minute to half an 

 hour, and subsequently to collect in masses agglutina- 

 tions. This reaction may occasionally be brought about 

 by normal blood if insufficiently diluted, but is charac- 

 teristic enough to be very useful in the diagnosis of ob- 

 scure cases. In a later paper Johnston states that to ob- 

 tain a satisfactory reaction an attenuated typhoid bacillus 

 is more useful than a highly virulent one. 



My own experiments have satisfied me of the value of 

 the test, both for making a diagnosis of the disease and 

 for confirming the species of the bacillus in doubtful 

 cases. 



It is now the opinion of all observers that cessation of 

 motion and agglutination of the bacteria, resulting from 

 the contact of typhoid bacilli and typhoid serum, are 

 inconclusive for diagnostic purposes unless the reaction 

 follows the combination of a suitable culture and a 

 deft n ite y u a u tity of sent ni . 



1 Montreal Mea. Journal ', March, 1897. 



