THE COMPOUND H^IMOLYSINS 253 



treated with bacteriolytic cholera-serum, from being de- 

 stroyed by guinea-pig-serum. This antialexic action was 

 in so far specific that it did not protect against other alexins 

 than that from guinea-pigs. Bordet made a large number 

 of experiments with the following combination : erythro- 

 cytes, from bullock ; immune-body, serum of rabbit injected 

 with erythrocytes from bullock ; alexin, normal serum from 

 a guinea-pig ; antiserum, serum from a guinea-pig treated 

 with normal rabbit-serum. The immune-body and the 

 antiserum were freed of alexin by heating to 55-56 C. 

 for thirty minutes. Bordet separated the active sub- 

 stances from a large number of other substances present 

 in the sera by letting the erythrocytes absorb them, then 

 only those substances that were specific to the erythrocytes 

 were able to act. That the erythrocytes absorb the im- 

 mune-body almost completely if it be not present in great 

 excess, we have seen above; and this method has long 

 been used for the extraction of immune-bodies from sera. 

 Bordet has shown that erythrocytes charged with immune- 

 body also absorb alexins, so that a serum may in this way 

 be freed from its content of alexin, which is indicated by 

 the fact that it has lost its hasmolytic power against ery- 

 throcytes treated with immune-body. The alexin is, on the 

 other hand, not absorbed by normal erythrocytes, those 

 that do not contain immune-body. Further, Bordet in an 

 analogous manner proved that erythrocytes, charged with 

 immune-body, absorb the antiserum and thereafter have 

 lost their power of absorbing alexin. Evidently the im- 

 mune-body is neutralised by the antiserum, which seems 

 to have a stronger affinity for the immune-body than has 

 alexin. This observation is confirmed by the fact that a 



