AGGLUTININS 81 



Other Applications of the Agglutination Phenomenon 



For the identification of certain species of bacteria, 

 the agglutination reaction is of the greatest value. 

 For this purpose, agglutinins are artificially produced 

 by injection of animals, usually rabbits, with cultui^es 

 of the various organisms whose presence is suspected 

 in given cases. Thus we have conditions reversed from 

 those obtaining in the Widal reaction for typhoid 

 fever, the serum being the known factor, and the or- 

 ganism the unknown. For example, we have isolated 

 an organism that we strongly suspect to be the ty- 

 phoid bacillus. If we find that a culture of this or- 

 ganism is agglutinated by the greatly diluted serum 

 from an animal previously immunized to typhoid 

 bacilli, and is not agglutinated by similar dilutions of 

 sera from animals immunized to other organisms, such 

 as B. jparatyphosus, dy sentence, etc., our suspicion is 

 converted into certainty. This method is of great 

 value, especially in the detection of typhoid bacilli in 

 milk and other fluids, as well as in other procedures. 



