SINGLE NATURE OF HEMOLYTIC IMMUNE BODIES. 341 



In dealing with this phenomenon, I have found the results as 

 given do not express the entire truth as I have found it. The 

 closes given in the "plugging" experiment described, are as follows: 



Guinea-pig washed corpuscles, 5 per cent suspension 1 c c 



Dog serum, 50 to 51 degrees 0.5 c c 



Guinea-pig serum 0.5 c.c. 



which doses I shall use in the experiments to be described. I have 

 found, as a matter of fact, that dog serum heated to the degree 

 mentioned does always give a slight hemolysis of guinea-pig cor- 

 puscles, a fact which is masked by the excess of salt solution used 

 in the 5 per cent suspension. If we deal with the centrifugalized de- 

 posit of 1 c.c. of a 5 per cent suspension, or simply with 0.05 of a cubic 

 centimeter of washed corpuscles, this hemolysis is clearly shown. 

 That dog serum heated for one-half hour to 50 degrees, 51 degrees 

 or 52 degrees does possess distinct hemolytic power for guinea-pig 

 corpuscles may be shown more distinctly in the following way: 

 If we prepare a series of tubes each containing 1 c.c. of suspensions 

 of corpuscles of 5 per cent, 3 per cent, 1 per cent and one-half per 

 cent respectively, and to each tube add the given dose of heated dog 

 serum (0.5 of a cubic centimeter, 50 to 51 degrees), we find after 2 

 hours at 37° C that in the tubes at 1 per cent and one-half per cent 

 hemolysis is complete; or, better still, if we use the centrifugalized 

 deposits of such a series of suspensions without the excess of salt 

 solution, we find that hemolysis is complete in the tubes at 3 per 

 cent, 1 per cent and one-half per cent and marked in the 5 per cent 

 tube. It is evident from such an experiment that the so-called 

 " complementoid " is nothing more than a " complement " the hemo- 

 lytic activity of which has been impaired, but not destroyed, by the 

 heating. That the subsequent addition of guinea-pig serum does 

 not sensibly increase the hemolysis in such a series of tubes is per- 

 fectly true, which means that there is a "plugging" (Verstopfung) 

 by means of the partially destroyed " complement. " The combining 

 power of the "complement" has been no more destroyed than the 

 toxic power. If, instead of dog serum heated to 51 degrees, we use 

 dog serum heated to 56 degrees, we find another more striking exam- 

 ple of this modified "complement." To a similar series of tubes at 

 5 per cent, 3 per cent, 1 per cent and one-half per cent respectively 

 add 0.5 of a cubic centimeter of dog serum heated to 56 degrees for 



