AGGLUTINATION 363 



5. Agglutination. 



Shiga was the first to show that the serum of persons suffering from 

 dysentery agglutinates the bacillus. 



1. Agglutinating properties of experimental serums. The serum of an 

 immunized animal has the property of agglutinating the bacillus used for its 

 immunization. The most highly agglutinating serums (^^^^i^^^) are 

 obtained by inoculating animals intra-venously. 



(a) The serum of normal animals has no action on the dysentery bacillus. 

 ((3) Antidysentery serum is specific and has no agglutinating action on 

 the typhoid, colon s or paratyphoid bacilli. 



(7) The serum of animals immunized with the Shiga bacillus agglutinates 

 that organism but has no action on bacilli of the Flexner type. 



(8) The serum of animals immunized with bacilli of the Flexner type 

 agglutinates these bacilli but not the Shiga bacillus. 



[(e) Hiss' Y bacillus is agglutinated by a Flexner serum but not by a 

 Shiga serum. Strong's bacillus is agglutinated neither by a Shiga nor by a 

 Flexner serum.] 



2. Agglutinating properties of the serum of persons suffering from 

 dysentery. In testing the agglutinating properties of the serum of a dysentery 

 patient it is important to recognize that the Shiga bacillus is only agglutinated 

 in low dilutions (rarely in dilutions higher than -V~TJo) an( i that bacilli of 

 the Flexner type are agglutinated in much higher dilutions (5^) an d may 

 even be agglutinated by normal serums in low dilution. 



(a) The serums of healthy persons [exceptis excipiendis] and of patients 

 suffering from diseases other than dysentery do not agglutinate the dysentery 

 bacilli. 



(j3) The serum of patients suffering from amoebic dysentery does not 

 agglutinate the dysentery bacilli. 



(7) The serum of patients suffering from bacillary dysentery agglutinates 

 the bacillus causing the infection and with rare exceptions has no action on 

 the other type : the serum of a patient infected with the Shiga bacillus 

 agglutinates the Shiga bacillus while having no action on bacilli of the 

 Flexner type, and vice versa. 



Whatever the type of bacillus causing the infection agglutination-capacity 

 is present in the serum only in severe or averagely severe cases ; it seldom 

 appears before the end of the first week and occasionally not until later, but 

 remains for several weeks after recovery. 



(S) The serums of dysentery patients never agglutinate the typhoid 

 bacillus ; but such a serum may agglutinate some varieties of the colon 

 bacillus, the explanation being, possibly, that a colon bacillus infection has 

 been superadded upon the original dysentery infection. 



6. Precipitins. 



If one drop of Shiga serum be added to ten drops of a filtered culture of 

 the Shiga bacillus a precipitate is formed : a similar but less marked pre- 

 cipitate is also formed if instead of the Shiga culture, a culture of one of the 

 bacilli of the Flexner type be used. 



Conversely, Flexner serum precipitates filtered cultures of bacilli of the 

 Flexner type and also but less markedly filtered cultures of the Shiga bacillus. 



7. Immune body. 



In the serum of persons suffering from dysentery and also in the serum of 

 immunized animals a specific immune body is present which is fixed both 



