THE COMPOUND H^MOLYSINS 2 19 



utes to 55 C., but may be restored by the addition of 

 normal serum. 



The action of such an immune-serum is augmented by 

 the addition of fresh serum, as Ehrlich and Morgenroth l 

 found, and the haemolytic power of the heated immune- 

 serum may after the addition of normal serum exceed 

 many times that of the original immune-serum before 

 being heated. These observations led to the opinion, as 

 was said above (p. 20), that the immune-serum contained 

 two substances, the one the so-called immune-body (or 

 amboceptor), stable at 55 C., and another, the alexin (com- 

 plement), present even in normal serum, labile and de- 

 stroyed at 55. 



Moreover, the immune-serum contains, as Bordet found, 

 a substance which agglutinates erythrocytes of the injected 

 variety. This agglutinin resists heating to 60 C., but 

 loses its agglutinating properties at 70 C. 



As is seen from the experiments considered on p. 150, 

 the immune-body is absorbed by the erythrocytes in large 

 measure. If the quantity of immune-body present is not 

 very great, it will be practically completely absorbed by 

 the erythrocytes. Therefore, if erythrocytes are shaken 

 for an hour with their specific immune-serum that has been 

 heated, this serum is afterward innocuous to other ery- 

 throcytes, even after alexin has been added. But the 

 erythrocytes which have absorbed the immune-body may, 

 after separation from the serum by centrifugation, be 

 dissolved on adding an alexin to them. 



In an analogous manner it is possible to show that the 

 alexin is not absorbed to a noteworthy degree by the ery- 



1 Ehrlich and Morgenroth : Berliner klin. Wochtnschrift, 1899, No. 22, 



