422 



Mr. H. E. Dean. 



[Oct. 13, 



to be to enormously increase the action of a dilution of antiserum, which 

 if acting by itself would have produced a hardly perceptible degree of 

 agglutination. 



The solution of middle-piece was shown by repeated experiments to have 

 no agglutinative action on the red corpuscles in the absence of the antiserum. 

 It is evident from Table I that a very marked degree of agglutination may 

 be produced by the interaction of three components — the red cells, the heated 

 homologous antiserum, and the solution of middle-piece. 



Remarks on Table I. 

 From a consideration of Table I it appears probable that for the agglutina- 

 tion of the red cells two substances are necessary, the one being the specific 

 antibody to the red cells and the other a non-specific substance. Both of 

 these substances are thermostable, and are present in inactivated hsemolytic 

 serum. The larger quantities of the antiserum contained, in addition to 

 the specific antibody, a sufficient quantity of the non-specific substance 

 to produce agglutination of the red cells. If a smaller quantity of the 

 antiserum was used, the amount of non-specific substance was insufficient. 

 In such cases the necessary substance could be supplied by the addition 

 of the solution of middle-piece. An effect of this type is illustrated in 

 Table II. 



In this experiment an amount of antiserum was employed which, acting 

 by itself, was unable to agglutinate the quantity of red cells present. Such 

 a quantity of antiserum was found to be 1 c.c. of a 1 in 200 dilution. 



Table II 



of dilutions of 

 middle-piece 

 solution. 



Drmal saline 

 (. 1—200 



Neither the antiserum alone, in a 1 in 200 dilution, nor the solution of 

 middle-piece was able by itself to agglutinate the red cells. The two factors 

 in combination produced a very marked degree of agglutination. 



