268 AGGLUTININS 



independent of Widal, but, owing to a lack of patients, Widal preceded 

 him in the publication of a more extensive work. 



At the present time this diagnostic reaction is known as the Grubler- 

 Widal reaction. It has proved of great value to a large number of dif- 

 ferent investigators, not only in making the serum diagnosis of typhoid 

 fever, but hi other infections as well. 



Normal and Immune Agglutinins. Normal serums are frequently 

 capable of agglutinating bacteria, such as the typhoid, colon, pyocy- 

 aneus, and dysentery bacilli. In some cases the typhoid bacillus may be 

 agglutinated in dilutions as high as 1 : 30, a point of practical impor- 

 tance in the clinical use of the test. When a normal serum is found to 

 have a high agglutinating power, it is probable that 

 a 'previous infection by the microorganism has oc- 

 curred. Since the serum of a new-born child is 

 largely devoid of agglutinins that are found in later 

 life, the so-called normal agglutinins may, after all, 

 ' be acquired properties. 



FIG. 76. THEO- ^he term immune agglutinin is applied to the 



RETIC STRUC- 

 TURE OF AGGLU- agglutinating substance in a serum developed as the 



GLuriNoiD result of infection or of systematic immunization 



1, Agglutinin: with the microorganism. 



|ou^ aP for P union Formation of Agglutinins. -According to Ehr- 



with antigen; A, the lich's side-chain theory, agglutinins are antibodies of 

 agglutmophore or . 



zymophore group. the second order (Fig. 7o) . They resemble antitoxins 



2, Agglutmoid. or rece ptors of the first order in possessing an affinity- 

 oame structure as 



agglutinin, except bearing or haptophore group that unites with the 



thab the agglutino- .. v? ./ ' -i i 



phore or zymophore antigen, but they differ from them in having also a 



group is lost. functional or agglutinophore group that agglutinates 



the antigen when this union has occurred (Fig. 76). 



Agglutinins that have lost their zymophore or agglutinophore group 

 through the action of heat, age, acids, etc., but that still possess their 

 haptophore group, are called agglutinoids, just as toxins that have lost 

 their toxophore group are called toxoids. Such agglutinoids, then, may 

 still combine with the bacteria or blood-cells without being able, how- 

 ever, to produce agglutination (Fig. 77). 



It is found, at times, that even a fresh serum, when concentrated, 

 will cause less agglutination than when it is diluted. This is ascribed to 

 the presence of agglutinoids, which have a stronger affinity for agglutin- 

 ogen than has the agglutinin. When producing a reaction of this char- 

 acter they are called pro-agglutinoids. When the serum is diluted, the 



