212 



COLLECTED STUDIES IN IMMUNITY. 



TABLE II. 

 GUINEA-PIG BLOOD. 



the amboceptors, that this binding will not take place if the experi- 

 ment is performed at C. These considerations confirm our view 

 that the impossibility of activating the blood-cells sensitized at 37 C. 

 is due to a blocking of the complementophile amboceptor groups of 

 the dog serum by the complementoids of the same serum. 



2. It still remained to show that the substance which prevented 

 the binding subsequent to the binding effected at C., was really 

 present in the fluid medium. This could easily be shown in the 

 following manner. Two parallel series of tubes with guinea-pig blood 

 were treated at C. for one and one-half hours with inactive dog 

 serum (i.e., containing amboceptor + complementoid). The tubes of 

 series A were then centrifuged and the sediments, freed from fluid, 

 suspended in physiological salt solution; the tubes of series B were 

 left unchanged. All the tubes were now placed into the incubator 

 for one hour, then centrifuged, and the sediments mixed with active 

 guinea-pig serum and physiological salt solution. In the tubes of 

 series A solution ensued, the blood-cells of series B remained undis- 

 solved, as can be seen from Table III. 



The substance which caused the blocking of the amboceptcrs was 

 therefore contained in the fluid portion of the blood sensitized at 0; 

 for in series A, in which the fluid medium was decanted, the blood- 

 cells although subsequently kept at 37 C., could still be activated. 

 In series B, on the contrary, the complementoids still remaining 

 free at C., were bound when subsequently kept in the thermostat, 

 and so prevented the "completion" with active serum. From all 

 this it follows that we can be dealing only with complementoid action 

 in the test-tube, and the correctness of this view is confirmed in 

 another way. 



