412 STUDIES IN IMMUNITY. 



Before Sachs' observations, Pfeiffer and Friedberger had studied 

 the inhibiting effect of normal serum on bacteriolysis of the cholera 

 vibrio. Their sensitizer, which was very active against the vibrio, 

 was first removed by treating the immune serum with vibrios, 

 followed by centrifugalization and decanting of the serum: the 

 supernatant fluid so obtained, on injection into the peritoneal cavity 

 of a normal animal together with vibrios sensitized by a moderate 

 dose of anticholera serum, prevents bacteriolysis. Pfeiffer and 

 Friedberger further noted that for the antagonistic power to be 

 manifest a moderate sensitization only should be used. They 

 have studied the conditions affecting the phenomenon with great 

 care and reserve any decision as to its interpretation. 



Sachs' findings in hemolysis are analogous to those of Pfeiffer 

 and Friedberger. There can be no doubt that any explanation 

 for one will serve for the other; the inhibiting property of certain 

 constituents of serum on the fixation of alexin on sensitized blood 

 cells, as opposed to salt solution, is doubtless applicable to bacte- 

 riolysis as well. A single objection occurs : when faintly sensitized 

 vibrios are injected into the peritoneal cavity bacteriolysis does or 

 does not take place, depending on whether antagonistic serum has 

 or has not been previously added. But why is such serum necessary 

 to protect the vibrios? Does not the peritoneal cavity contain a 

 certain amount of an exudate which resembles the antagonistic 

 serum at least more closely than it does salt solution? Why, then, 

 does not this exudate inhibit bacteriolysis? 



We find by experiment that peritoneal exudate, even when heated, 

 has no more inhibiting effect on hemolysis* than salt solution. For 

 example, a little peritoneal exudate from a rabbit was heated to 

 56 degrees. At the same time the serum of the same animal was 

 obtained and treated in the same manner. One-twentieth of a 

 cubic centimeter of moderately sensitized bovine blood (rabbit > ox 

 serum) is placed in each of several tubes, and 0.3 of a cubic centi- 

 meter of salt solution, normal serum or peritoneal exudate, respec- 

 tively, is added; 0.05 of a cubic centimeter of fresh guinea-pig 

 serum is then added to each tube. Hemolysis appears rapidly in 

 the mixture containing salt solution and almost as soon in the one 



* It seems that from the close analogies between bacteriolysis and hemolysis 

 any conclusions referring to one are applicable to the other. 



