H^MOLYTIC AND OTHER SERA. 483 



some serum from a fresh (i.e. non-treated) animal. These 

 observations have been fully confirmed, and it may be stated 

 that in each case the haemolytic property is "practically 

 specific," i.e. is exerted only towards the corpuscles used in the 

 injections ; moreover, by the injection of corpuscles from more 

 than one species of animal, a serum with multiple haemolytic 

 properties may be obtained. Ehrlich and Morgenroth analysed 

 the phenomena in question, and showed that the specially 

 developed and heat-resisting substance, "immune-body," entered 

 into combination with the red corpuscles at a comparatively low 

 temperature. This was shown by adding the heated serum to 

 the red corpuscles in salt solution (of course no haemolysis 

 occurs), and after some time centrifugalising the mixture. On 

 separating the corpuscles it was found that the haemoglobin was 

 set free on the addition of some serum from a fresh animal ; it 

 was also found that the immune-body was absent from the clear 

 fluid. In other words, the red corpuscles fix or become com- 

 bined with the immune-body. In a corresponding manner they 

 came to the conclusion that the immune-body combined with the 

 complement (in normal serum), though the combination was less 

 firm and only occurred at a higher temperature best about 

 37 C. They therefore consider that the immune-body acts as a 

 sort of connecting link between the red corpuscle and the com- 

 plement. Bordet, on the other hand, holds that the immune- 

 body acts merely as a sensitising agent hence the term sub- 

 stance sensibilisatrice and allows the ferment-like complement 

 to act. Regarding the important fact that in the case of each 

 anti-serum of this group a special immune-body is developed, 

 and that the laws of haemolysis are identical with those of 

 bacteriolysis, practically all are agreed. It is a disputed point 

 whether there are several distinct complements in a normal 

 serum with different relations to different immune-bodies, for 

 which Ehrlich and his co-workers have brought forward a large 

 amount of evidence, or whether, as Bordet holds, there is a 

 single complement, which may, however, show slight variations 

 in behaviour towards different immune bodies. Workers of the 

 French school also hold that complement does not exist in the 

 free condition in the blood, but is liberated from the leucocytes 

 when the blood is shed ; though this cannot be held as proved, 

 there is evidence that the amount of free complement in- 



