26 VACCINE AND SERUM THERAPY 



contained in plague-immune serum — that is, it has 

 become fixed, so that when later the hemolytic 

 ambocei^tor contained in heated hemolytic serum is 

 added there is no free complement present to activate 

 it, therefore no hemolysis of the red cells occurs. 



In (B) there is no bacteriolytic amboceptor present, 

 therefore such complement remains free, to later 

 combine with added hemolytic amboceptor, which it 

 activates with a consequent hemolysis of red cells. 



The Specificity of Hemolysins. — In the preceding 

 paragraphs it has been shown that the blood cells of 

 one animal injected into an animal of another species 

 give rise to hemolytic substances in the blood serum 

 of the second animal, which is strictly specific for the 

 variety of cells injected. These hemolysins are called 

 " heterolysins." Such hemolysins can also be produced 

 by injecting the blood cells of one species of animal 

 into another — for instance, by injecting the red cells of 

 a goat into another goat hemolytic substances are 

 formed in the blood of the previous goat, which are 

 strictly specific for the animal from whom the red cells 

 were taken ; these hemolysins are called "isolysins." 



So far, the experimental production of autolysins — 

 that is, of substances in the blood serum which will 

 produce hemolysis of the individual's own corpuscles — 

 has not been successful. On the other hand, autolysins 

 have been discovered in the blood serum of animals 

 suffering from paroxysmal hemoglobinuria. In these 

 cases the sensitising substance, or amboceptor, 

 ai3peared to be absorbed by the red blood cells 



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