AGGLUTINATION AND PRECIPITATION 



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is called the agglutinophore, the zymophore, or the zymotoxic group. 

 This group is unstable, and may be destroyed by heating to a tem- 

 perature of 60 to 75 and by acids and alkalis. It changes with 

 age slowly. An agglutinin which has lost its zymotoxic group is 

 called an agglutinoid. The agglutinoid still fetains the capacity 

 to unite with the antigen, but has lost the ability to act upon it. 

 The presence of agglutinoids may be demonstrated by mixing a 

 serum containing them with the homologous organism, and allow- 

 ing the mixture to stand for a time. No agglutination will take 

 place, nor will it occur when fresh agglutinin is added. The 



3. ' ' '4. 



Fig. 73. Agglutination and formation of agglutinins: 1, Diagrammatic 

 representation of bacterial or other antigenic cells with fixed (a) and freed (6) 

 agglutinogen groups. 2, Union of agglutinogen with cell receptors of the 

 second order: a, Molecule of the cell protoplasm, with a cell receptor of the first 

 order (e) and of the second order (6) , showing its haptophore (c) and its aggluti- 

 nophore or zymophore (d); f, an agglutinogen group united to the cell receptor. 

 3, Overproduction of cell receptors 6 and freed receptors or agglutinin molecules 

 at c. 4, Union of agglutinin with the bacterial or other cell. 



agglutinoid unites with the cell and blocks the union of the ag- 

 glutinin. Certain investigators have claimed to have produced 

 antiagglutinins by the use of agglutinins as an antigen, inoculating 

 them into another species of animal. These antiagglutinins, when 

 mixed with the agglutinins, unite with them and prevent them from 

 uniting with the homologous antigen when it is added. 



Body or Somatic and Flagellar Agglutinins. It is probable that 

 agglutinogen in motile organisms may originate in two ways from 

 the flagella or from the cell-bodies. Agglutinins have been differ- 

 entiated in such cases into those that bring about agglutination 



