H&MOLYSINS 9 



Bordet, in 1896, showed that in order for the spe- 

 cific immune serum to dissolve bacilli in a test-tube, 

 it is unnecessary to add fresh normal serum or 

 peritoneal fluid; but that immune serum freshly 

 drawn from the vein is able even under these cir- 

 cumstances to dissolve the bacilli. 



Analogy of the Bacteriolytic and Haemolytic Proc- 

 esses Active and Inactive Bacteriolytic Sera. Now 

 that the main points in cholera immunity are 

 clear to us, the close analogy between this and the 

 subject of haemolysis is apparent. Just as, when 

 immunizing an organism against cholera bacilli 

 the organism responds with an increased solvent 

 power for those bacteria, so does the organism 

 respond when it is treated, i.e. immunized, with 

 red cells of another species, by increasing the solv- 

 ent power of its serum for those particular cells. 

 Furthermore, just as the haemolytic process was 

 seen to depend on the combined action of two sub- 

 stances, one developed in the haemolytic serum, 

 the other already present in normal serum, so also 

 in the bactericidal process just studied there are 

 two factors. It is easy to understand, therefore, 

 what formerly was not at all clear, why a specific 

 bactericidal serum against cholera, typhoid, or 

 other infectious disease should not act in a test- 

 tube unless there had first been added some normal 

 serum (according to Metchnikoff), or there had 

 been employed a perfectly fresh serum (according 

 to Bordet) : simply because in either of these 



