LYSINS, AGGLUTININS, PRECIPITINS, ETC. 227 



them by centrifugalization. To the supernatant fluid, they now added 

 sheep-blood corpuscles and normal goat serum (complement) and found 

 that no hemolysis took place. The immune body had apparently gone 

 out of the serum. The red cells which had been in contact with the serum 

 and separated by the centrifuge were then washed in salt solution and 

 to them complement was added in the form of fresh normal serum. 



ItTHTtunismg Subslgtice Complement 



BodyCcU 



Fig. 57. — Ehrlich's Conception op Cell-Receptors, Giving Rise to Lytic 

 Immune Bodies (Haptines of the Third Order). 



Hemolysis occurred. It was plain, therefore, that the immune bodj^ 

 of the inactivated serum had gone out of solution and had become at- 

 tached to the red blood cells, or, as Ehrlich expressed it, the immune 

 body by means of its "haptophore" atom-group had become united 

 to the corpuscles. In contrast to this, if normal goat serum (containing 



- Complement 

 wiTnune hotiy 



Cell used for immuni^int^ 



Fig. 58. — Complement, Amboceptor or Immune Body, and Antigen oa. 

 Immunizing Substance. 



complement only) was added to sheep corpuscles and separated again 

 by centrifugalization, the supernatant fluid was found to be still capable 

 of reactivating inactivated serum (immune body) . This he interpreted 

 as proving that the complement was not bound to the corpuscles directly. 

 If the three factors concerned — corpuscles, immune body, and 

 complement — were mixed and the mixture kept at 0° C, no hemolysis 



