432 



Mr. H. B. Dean. 



[Oct. 13, 



the heated antiserum, and the substance present in the middle-piece fraction 

 of guinea-pig complement. 



Sufficient experiments have not been performed to justify a definite 

 statement as to the relation of the phenomena of conglutination and 

 agglutination. Nevertheless, it seems possible that agglutination and con- 

 glutination are essentially the same process. This process is the aggregation 

 or precipitation of a precipitable substance by the interaction of antigen 

 and antibody. In the case of agglutination tins substance is a constituent 

 of the agglutinating serum. In the case of conglutination a further supply 

 of this substance is supplied from another source (ox serum). 



The phenomenon described under the name of co-agglutination is of great 

 interest in that the antigen is not a constituent of the agglutinated cell, 

 but is derived from some different source. In such an experiment the 

 interaction of antigen with antibody produces such a change in the physical 

 conditions of the mixture that the suspended corpuscles, winch may be 

 supposed to have no affinity for the antigen or antibody, are spontaneously 

 agglutinated. The result suggests the possibility that in an ordinary 

 agglutination experiment the corpuscles may be agglutinated as the result 

 of a reaction between antibody and antigen, which has diffused out of the 

 corpuscle into the surrounding fluid. If such a view be correct, it follows 

 that the phenomena described as agglutination, conglutination, and 

 co-agglutination are essentially the same. 



Apart from the question of agglutination, the results recorded may possibly 

 be found to have some bearing on other serum reactions. The influence of 

 the middle-piece and end-piece fractions of the complement in phagocytosis 

 has been investigated by Dr. Ledingham in conjunction with the author, and 

 the results of these experiments are shortly to be published. 



With regard to the formation of precipitates, the experiments suggest that 

 a suitable mixture of serum and antiserum is capable of precipitating a non- 

 specific substance derived from the serum of a third animal. It seems, indeed, 

 probable that the reason why an antiserum, if diluted, loses its power of 

 producing a precipitate is not because the dilution contains too little anti- 

 body, but because there is not sufficient precipitable substance present to 

 produce a precipitate. 



It is sometimes held that, because a mixture of antigen with a dilution of 

 antiserum can be prepared which shows no precipitate and nevertheless 

 efficiently binds complement, the complement-binding antibody must be 

 different from the precipitate-forming antibody. Now it has been shown in 

 Table VI that a mixture of certain proportions of horse serum with its 

 homologous antiserum may remain quite clear, while on the addition of the 



