BACTERIOLYSINS AND HMMOLYSINS 77 



made, this inactive by heating to 55 C., so that 

 then it contained only the substance sensibilatrice. 

 Next they added a sufficient quantity of sheep 

 red cells, and after a time centrifuged the mixture and 

 separated the clear supernatant fluid from the red 

 cells. -They were now able to show that the red 

 cells had combined with all the substance sensi- 

 bilatrice, and that the supernatant clear liquid was 

 free from the same. In order to prove that such 

 was the case they proceeded thus: To some of the 

 clear centrifuged fluid they added more sheep red 

 cells; and, in order to reactivate the serum, a suffi- 

 cient amount of alexin in the form of normal serum 

 was also added. The red cells, however, did not 

 dissolve there was no substance sensibilatrice, 

 because it had been absorbed and removed by the 

 first addition of red cells. The next point to prove 

 was that this substance had actually combined with 

 the red cells first added; therefore the red cells 

 which had been separated by the centrifuge were 

 mixed with a little normal salt solution after freeing 

 them as much' as possible from fluid. Then a little 

 alexin in the form of normal serum was added. 

 After remaining thus for two hours at 37 C. these 

 cells had all dissolved. 



In this experiment, therefore, the red cells had 

 combined with all the substance sensibilatrice, 

 entirely freeing the serum of the same. That the 

 action was a chemical one and not a mere absorp- 



