224 LECTURES ON IMMUNITY 



An experiment of Neisser and Wechsberg 1 seems to 

 indicate that immune-body and alexin, when mixed, really 

 enter into a compound, at least partially. They used 

 different bacteriolysins, which like the haemolysins are 

 of a compound nature, so that the presence of two differ- 

 ent substances, an immune-body and an alexin, is neces- 

 sary. They used a constant quantity of bacteria and of 

 alexin, to which they added different quantities of immune- 

 body. At first, as we know, the action increases with the 

 concentration of the immune-body, but finally reaches a 

 maximum ; and, if this quantity exceeds a certain magni- 

 tude the effect then decreases, so that the bacteria may 

 even not be destroyed. This phenomenon has been called 

 the "diversion" (Ablenkung) of the alexin. As the ex- 

 periments with bacteriolysins are not very well adapted 

 to quantitative experiments, the following hsemolytic 

 experiments with ox erythrocytes, immunised rabbit- 

 serum as immune-body, and guinea-pig-serum as alexin, 

 may serve to elucidate the relations. In the following 

 table the quantity of alexin present in 2.5 c.c. of solution 

 is called b, and the corresponding quantity of immune- 

 body is called a. As unit is taken the thousandth part of 

 the quantity contained in I c.c. of the two original prep- 

 arations. The quantity of erythrocytes was I c.c. of a 

 5 per cent suspension of ox blood. The mixture, which 

 had been kept for thirty minutes at 24 C, was allowed to 

 act on the erythrocytes for two hours at 37 C. In this 

 manner I found the following degrees of haemolysis (com- 

 plete haemolysis = 100) : - 



1 Neisser and Wechsberg: Munch, med. Wochenschrift (1901). 



