n8 



Immunity 



that horses which had been treated with the blood-corpuscles 

 of rabbits contain in their serum constituents which are 

 poisonous for the rabbit, and for the rabbit only." . . . 

 "Bordet showed shortly thereafter that in the case quoted 

 there was present in the serum a specific hemolysin which 

 dissolved the corpuscles of the rabbit. He also proved that 

 these hernolysins as had already been shown by Buchner 

 and Daremberg in the case of similarly acting bodies which 

 are present in normal blood lost their solvent property on 

 being maintained during half an hour at a temperature of 

 55 C. Bordet added, further, a new 

 fact, that the blood-solvent property 

 of those sera which had been deprived 

 of solvent power by heat, the solvent 

 action could be restored if certain nor- 

 mal sera were added to them. By this 

 important observation an exact analogy 

 was established with the facts of bacteri- 

 olysis as elicited by the work of Pfeiffer, 

 Metschnikoff, and Bordet." .... 



. . . "In collaboration with Dr. 

 Morgenroth, I have sought in regard to 

 this question, for which hemolysis offered 

 prospects favorable to experimentation, 

 to make clear the mechanism concerned 

 in the action of these two compounds 

 the stable, which may be designated 

 'immune body,' and the unstable, which 

 may be designated 'complement' which 

 acting together effect the solution of the 

 red blood-corpuscles. For this purpose, 

 in the first place, solutions containing 

 either only the 'immune body ' or only the 'complement' 

 were brought in contact with suitable blood-corpuscles, and 

 after separation of the fluid and the corpuscles by centrifu- 

 galization, we investigated whether these substances had 

 been taken up by the red corpuscles or remained behind in 

 the fluid. The proof of its location in the one position or in 

 the other was readily forthcoming, since to restore the 

 hemolysin to its former activity, it was only necessary to 

 add to the 'immune body' a fresh supply of 'complement,' 

 or to the 'complement' a fresh supply of 'immune body' 

 in order that the presence of the hemolysin in its integrity 



Fig. 14. Com- 

 bination of cell (a), 

 amboceptor (6), 

 and complement 

 (c~). The ambo- 

 ceptor may unite 

 with the cell, but 

 cannot affect it 

 alone. The com- 

 plement cannot 

 unite with the cell 

 except through the 

 amboceptor, hav- 

 ing no adaptation 

 to the cell directly. 



