CHAPTEE XIII. 



Widal and 

 Grnnbanm. 



THE PHENOMENON OF AGGLUTINATION. 



Agglutination, in the bacteriologic sense, refers 

 to the clumping and sedimentation of a homogene- 

 ous suspension of micro-organisms by the action of 

 a serum. 



specificity. Although a number of investigators had ob- 

 served the phenomenon of agglutination, Gruber 

 and Durham first saw its significance. They found 

 that the reaction was a specific one, i. e., that the 

 serum which would cause the strongest agglutina- 

 tion of a micro-organism was that of an animal 

 which had been made immune to it by repeated 

 injections. 



WidaFs service consisted in the utilization of the 

 phenomenon as an aid in the diagnosis of typhoid 

 fever. He is the originator of clinical serum 

 diagnosis. It is perhaps largely a matter of acci- 

 dent that we speak of the Widal reaction rather 

 than the Griinbaum reaction. Griinbaum was car- 

 rying on the same work at the same time, but 

 Widal preceded him in the publication of his more 

 extensive work. 



In the chapter on natural immunity it was 

 stated that normal serums often are able to ag- 

 glutinate bacteria. Normal human serum may ag- 

 glutinate the typhoid, colon, pyocyaneus, and dys- 

 entery bacilli, and occasionally the staphylococcus 

 and cholera vibrio; it does not agglutinate the 

 streptococcus and some other organisms. In cer- 

 tain cases it may agglutinate the typhoid bacillus 



Normal 

 Agglntinins. 



