THE COMPOUND H^MOLYSINS 255 



other observation of Bordet. 0.2 c.c. of bovine erythrocytes 

 loaded with immune-body were mixed with 0.6 c.c. of 

 antiserum and physiological salt-solution. After a time the 

 erythrocytes were separated from the liquid by centrif ugal- 

 isation. To the erythrocytes was then added a mixture of 

 0.2 c.c. of alexin from the guinea-pig with 0.6 c.c. of 

 normal guinea-pig-serum heated to 56 C. Another ex- 

 periment was quite similar, but instead of the O.6 c.c. of 

 guinea-pig-serum, 0.6 c.c. of physiological salt-solution 

 was added. In the first experiment no haemolysis was 

 observed, but the second gave haemolysis during the course 

 of one hour. The absorption of the alexin was much 

 greater in the presence of the physiological salt-solution 

 than in the presence of normal serum. The absorbed 

 alexin competes with the antiserum absorbed in the erythro- 

 cytes, so that a certain quantity of compound haemolysin 

 was formed, enough to yield haemolysis. 



This action of the physiological salt-solution which 

 causes the absorption of, e.g., the immune-body and the 

 alexin from horse-serum in the experiment of Bordet and 

 Gay, speaks very much in favour of the view that an ab- 

 sorption and not a chemical binding of the immune-bodies 

 takes place in the erythrocytes. 



Through absorption experiments Bordet proved that the 

 same antiserum protects bovine erythrocytes against the 

 immune-body contained in serum from a rabbit treated with 

 bovine erythrocytes, and chicken erythrocytes against rab- 

 bit-serum treated with chicken erythrocytes. The same 

 antiserum may therefore neutralise two entirely different 

 immune-bodies, which are produced by the same species 

 of animal (here rabbits). Therefore Bordet rejects the 



