188 



BACTERICIDAL OR ANTI-BACTEEIAL IMMUNITY. 



the formation of adaptive substances of two classes, anti immune substances and anti 

 complements, cannot be entered upon here. 



In view of the rationale of cytolysis, as just set forth, we may consider the immune 

 substance to be an intermediarj' between the alexin and the cell to be destroyed ; or, on 

 the other hand, we may consider the alexin as the complement to the immune substance, 

 since only through their union is the toxic action possible. 



In fact, following Ehrlich, one sometimes speaks of the immune body as the inter 

 mediary body, or intermediary substance, but since it is furnished with two combining 

 affinities, it is now usually called the amboceptor. Furthermore, since the experimental 

 analysis of the lytic process by the new technique has shown that the germicidal and 





FIG. 90. DIAGRAM ILLUSTRATING CYTOLYSIS IN ACCORDANCE WITH EHRLICH'S HYPOTHESIS. 



A a, Cell; h, immune substance (amboceptor) : c, alexin (complement) : d, ceil receptor: e, atom 

 complex of the amboceptor capable of uniting with the receptor d; f, atom complex of the amboceptor 

 capable of uniting with the haptophorous group, y, of the complement, c. 



B ft, Cell; h, immune substance (amboceptor.: c, alexin (complement); d, cell receptor- h. anti- 

 alexin (anticomplement). 



C a, Cell; h, immune substance (amboceptor); c, alexin (complement); d, cell receptor 1 i, anti- 

 immune substance (anti-amboceptor) 



destructive action of blood serum, formerly supposed to be due to a single substance 

 called alexin, is really due to the combined action of two substances, the use of the 

 word alexin for one of them is misleading and has now been largely given up. The 

 substance present in the serum of both normal and adapted animal through which lysis 

 is effected when it is linked to the cell by the amboceptor is called the complement. 

 Other names have been applied to these hypothetical complexes or substances which 

 we cannot consider here. 



It was natural in the early studies on bacteriolysis, which were incidental to re- 

 searches on immunity, that the new substance which was found in the serum as the re- 

 sult of the immunizing process should be called the immune substance or immune body. 

 It was natural also, although less appropriate, to apply the same term, immune sub- 

 stances, to the analogous substances which appeared in the serum as the result of the 

 injection in the same fashion of cells and other materials which were not infectious, not 



