THE COMPOUND H^EMOLYSINS 221 



in the blood-corpuscles to cause a trace of laking. As 

 soon as the alexin is bound, new quantities of it diffuse 

 into the blood-corpuscles. Therefore the haemolysis in- 

 creases if corpuscles loaded with immune-body are treated 

 with fresh alexin. On the other hand Ehrlich and Mor- 

 genroth found that the fluid in which the erythrocytes had 

 been suspended for one or two hours at o C. contained 

 alexin. In this manner they showed that even the haemo- 

 lysins in normal sera (for instance goat-serum acting 

 upon guinea-pigs' erythrocytes) are formed by the union 

 of an immune-body and an alexin. They also stated that 

 a given immune-body combined with different alexins (nor- 

 mal sera from different animals) gives haemolysins of very 

 different haemolytic power, which eventually may be due to 

 many different circumstances. 



Ehrlich and Morgenroth supposed that the compound of 

 immune-body and alexin, i.e. the haemolysin, which is pres- 

 ent in the mixture of their solutions, is the active part and 

 that it is chemically bound to the erythrocytes, which are 

 regarded as if they were molecules. To explain the failure 

 of the reaction at o C. they supposed that the haemolysin 

 is nearly completely dissociated at low temperatures, o C., 

 but not at 40 C. ; this presupposes that the union of im- 

 mune-body and alexin is accompanied by an extremely 

 great absorption of heat, which is in the highest degree 

 improbable. The membrane of the erythrocytes is evi- 

 dently to a very slight degree permeable to the haemolysin ; 

 and, therefore, it is only the haemolysin formed inside their 

 membranes which exercises a poisonous action on the 

 corpuscles, just as in the case of saponin and cholesterin. 

 These experiments do not teach us anything concerning 



