110 PROPERTIES OF ILEMOLYTIC SERA 



Other experiments in which ox's serum 55 and simple salt 

 solution were used in the control instead of guinea-pig's 

 serum 55, gave the same results. When rabbit's serum 

 55 is used, the diminished action of anti-immune-body 

 (owing to its combination with the natural immune-bodies) 

 is also shown by the much greater rapidity of lysis than is the 

 case in the control. 



We therefore see that of the three heated sera tested the 

 rabbit's is the only one which contains molecules capable of 

 combining directly with anti-immune-body and thus of diminish- 

 ing its action. 



The experiment quoted as an example was the one which 

 showed most prominently the direct combination of the 

 natural immune-bodies with anti-immune-body ; in certain 

 others it was practically imperceptible, though its influence 

 on the rapidity of lysis was quite apparent. On the whole 

 the results of the action of the natural immune-bodies in 

 dissociating the anti-immune-body, now to be recorded, are 

 more striking. The reason of this will be discussed below. 



THE DISSOCIATION OF ANTI-IMMUNE-BODY BY THE 

 CORRESPONDING NATURAL IMMUNE-BODIES 



Bordet found that the normal rabbit's serum 55 (containing 

 natural immune-bodies) had the power of separating anti- 

 immune-body after it had combined with red corpuscles 

 treated with immune-body. We have obtained in the case 

 of our anti-immune-body results similar to those of Bordet 

 and of striking character. The principle of the method of 

 demonstration is simply this : we take two series of tubes 

 containing the same amounts of red corpuscles, of IB and 

 of anti-IB ; and after time for combination is allowed the 

 corpuscles are centrifugalized and washed. To those of one 

 series normal rabbit's serum 55 is added ; to those of the 

 other series, guinea-pig's serum 55, as a control. After centri- 



