122 



PRACTICAL METHODS IN IMMUNITY. 



haemolysis of the specific foreign cell, is something normally present 

 in the serum of every animal, and which is capable of disintegrating a 

 foreign cell or bacterium, provided it can have access to the cell or 

 bacterium through an intermediary amboceptor (hence the ambo- 

 ceptor is sometimes called an intermediary body). This something 

 is called the "complement." It is by some called "alexine," by 

 others cytase (Metchnikoff). The complement cannot act upon and 

 destroy an invading bacterium or cell unless the amboceptor is 



FIG. 46. Receptor of the third order, and of some substance uniting with one 

 of them. (Journal 0} the American Medical Association. 1905. P 1369 ) 



c, Cell receptor of the third order an amboceptor; e, one of the haptophores of 

 the amboceptor, with which some food substance or product of bacterial disintegra- 

 tion (/) may unite; g, the other haptophore of the amboceptor with which com- 

 plement may unite; k, complement ; h, the haptophore; z, the zymotoxic group of 

 complements. 



present to make the necessary connection. The complement is 

 destroyed by a temperature of 56 C., so that, if we heat the serum 

 from an immune animal to 56 C., the complement it naturally con- 

 tains is destroyed, and the amboceptor it contains, which is not 

 injured by such a temperature, is incapable of destroying bacteria or 

 cells, unless we replace the complement which has been destroyed by 

 fresh complement. This is done experimentally by adding the serum 



