5 2 IMMUNE SERA 



the serum of the guinea pig treated with cholera 

 spirilla transmits an increased solvent power only 

 for cholera spirilla, but not for any other species of 

 bacteria. The active substance of such a bacterio- 

 lytic immune serum Pfeiffer called a specific bac- 

 tericide. If we allow some of this specific cholera 

 immune -serum to remain for some time outside of 

 the body, e.g. in a bottle, and then test it for 

 solvent properties against cholera spirilla, not in a 

 living body but in a test-tube, we shall find that its 

 power is almost nil. If we add to this serum in 

 the test-tube some fresh peritoneal exudate or 

 some other body fluid, suoh as serum of a normal, 

 untreated guinea pig, as Metchnikoff first did, we 

 find that this serum has now acquired the power 

 to rapidly dissolve cholera spirilla even in a test- 

 tube. Bordet, 1 in 1895, showed that in order for 

 the specific immune serum to dissolve spirilla in a 

 test-tube, it is unnecessary to add fresh normal 

 serum or peritoneal fluid; but that immune serum 

 freshly drawn from the vein is able even under 

 these circumstances to dissolve the spirilla. 



Haemolysis. In his experiments with the bac- 

 teriolysis of cholora spirilla, Bordet used as an 

 immune serum the serum of a goat that had been 

 immunized against cholera spirilla, and as alexin, 

 fresh normal guinea-pig serum. It often happened 

 that the latter contained a certain number of red 



1 Bordet, Annal. Inst. Pasteur, 1895. 



