BACTERIOLYSINS AND H^EMOLYSINS 87 



ently by Ehrlich and Morgenroth on the one hand, 

 and Bordet on the other. These authors succeeded 

 in producing an antih&molysin. The procedure is 

 closely related to the results gained by immuniza- 

 tion against bacterial poisons. A specific haemoly- 

 sin, one, for example, specific for rabbit blood, 

 derived by treating a guinea pig with rabbit red 

 cells, is highly toxic to rabbits. Injected into the 

 animals intravenously in doses of 5 c.c. it kills the 

 animals acutely, causing intra vitam a solution of 

 the red cells. Such a haemolytic serum, then, acts 

 the same as a bacterial poison, and it is possible to 

 immunize against this just as well as against a bac- 

 terial poison. For example, to keep to our illustra- 

 tion, rabbits are injected first with very small doses 

 of this specific haemolytic serum. The dose is 

 gradually increased until it is found that the animal 

 tolerates amounts that would be absolutely fatal to 

 animals not so treated. If some of the serum of 

 this animal is now abstracted and added to the 

 specific haemolytic serum, it is found that the power 

 of the latter will be inhibited. According to 

 Ehrlich an antihanwlysin has been formed. As 

 we know that the action of the haemolysin depends 

 on the combined action of two substances, the 

 immune body and the complement, the question 

 arises to which of these two the antihasmolysin is 

 related. Is it an anti-immune body or an anti- 

 complement? A study of this question shows that 



