THEORIES OF IMMUNITY. 



other species of animal, capable of producing 

 a precipitate in the blood of the same species 

 of animal from which the injections were 

 made. The precipitate found is soluble (in 

 some cases at least) in two per cent solu- 

 tion of sodium chloride, and is therefore not 

 a coagulation. 

 Proteolysis : the breaking up of proteid bodies 

 as seen in ordinary digestion in connection 

 with the intestinal glands; takes place in 

 dead material. 



Reactivated : used to denote the supplying of 

 fresh complement to an immune serum, pre- 

 viously made inactive by heat (55° C), thus 

 making the immune body active. (See Inac- 

 tivated.) 



Receptors: chemical affinities conceived by 

 Ehrlich as existing in the blood corpuscles, 

 other tissue cells, etc.; satisfied by corre- 

 sponding affinities in other substances (im- 

 mune bodies, toxines, etc.). 



Receptors of the first order : affinities in the cell 

 concerned with fixing relatively simple ma- 



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