PROPERTIES OF ANTISENSITIZERS. 287 



Tube a. Sensitized blood, 0.3 c.c; Normal guinea-pig serum, 56 degrees, 

 1.2 c.c. 



Tube b. Same as last, with guinea-pig > rabbit antiserum, 56 degrees, replac- 

 ing the normal serum. 



Tubes c and d. Same as "a" and "b" respectively, with non-sensitized blood 

 in place of sensitized blood. 



One hour later 0.1 of a cubic centimeter of alexin (fresh guinea- 

 pig serum) is added to each tube. Hemolysis takes place in tube 

 "a" in a few minutes; no hemolysis in the other tubes. The tubes 

 are shaken from time to time and after about five hours are cen- 

 trifugalized. The clear supernatant fluids are placed in separate 

 tubes, and 0.4 of a cubic centimeter of a mixture composed of one 

 part of washed ox blood to two parts of rabbit > ox serum, 5G 

 degrees, is added to each tube.* 



These new sensitized corpuscles are rapidly hemolyzed in all 

 tubes except the one containing supernatant fluid "a," where no 

 hemolysis occurs. f We conclude from this experiment that the 

 antiserum removes from sensitized corpuscles their power of fixing 

 alexin; such corpuscles act as do normal corpuscles. 



(E) Does the antisensitizer drive out the sensitizer from the 

 corpuscles by a process of washing, or does it unite with the sensitizer 

 joined to the corpuscle? 



We have just seen that if a sufficient amount of sensitized cor- 

 puscles is added to the antiserum the latter becomes inactive. 

 We might suppose that the antisensitizer drives out the sensitizer 

 from the corpuscles, and the fact that it becomes inert might be 

 due to a mutual saturation of the two antagonistic substances. 



Let us take 0.1 of a cubic centimeter of sensitized ox blood and 

 add to it 0.3 of a cubic centimeter of antiserum. After a little 

 contact we wash the corpuscles carefully in salt solution. After 

 centrifugalization and decanting we suspend the sedimented cor- 

 puscles in 0.3 of a cubic centimeter of an active normal guinea-pig 

 serum, and add 0.1 of a cubic centimeter of alexin. No hemolysis 

 occurs. Has the sensitizer with which the corpuscles were laden 

 been driven out by the antiserum and then removed from the fluid 



* The sensitizing serum in this mixture is relatively so large in amount that 

 no neutralization of it could take place in tube "6," even if the antisensitizer had 

 not been used up. 



f Hemolysis will take place in this tube on addition of a little more alexin. 



