378 STUDIES IN IMMUNITY. 



The following mixtures are made: 



Tube 1. Guinea-pig alexin, 0.1 c.c.; bovine serum (56 degrees), 0.3 c.c. 



Tube 2. Rabbit antiguinea-pig serum (56 degrees), 0.15 c.c.; bovine serum 

 (56 degrees), 0.3 c.c. 



Tube 3. Guinea-pig alexin, 0.1 c.c.; rabbit antiguinea-pig serum (56 degrees), 

 0.15 c.c.; bovine serum (56 degrees), 0.3 c.c. 



Tube 4. Guinea-pig alexin, 0.1 c.c.; rabbit antiguinea-pig serum (56 degrees), 

 0.15 c.c. 



Tube 5. Rabbit antiguinea-pig serum, 0.15 c.c. 



To each tube is then added 0.5 of a cubic centimeter of a 5 per 

 cent suspension of washed guinea-pig blood. At room temperature 

 the following results occur: 



In tube 3, in which the bovine serum affects sensitized and alex- 

 inized corpuscles, a very powerful agglutination occurs in a few 

 moments, and hemolysis is complete in 10 minutes. In mixture 4, 

 which is identical with 3 except in not containing bovine serum, 

 there is only slight agglutination, and hemolysis is incomplete in 

 half an hour. Tubes 2 and 5 that contain no alexin give a slight 

 agglutination, but no hemolysis. In tube 1 that contains alexin, 

 but no sensitizer, the corpuscles are not agglutinated and show only, 

 a very slow partial hemolysis which is incomplete on the following 

 day. This hemolysis is due, as we have already seen, to the fact 

 that heated bovine serum contains a weak sensitizer for guinea-pig 

 corpuscles.* 



Now that we have determined that the heated bovine serum 

 acts by adhesion of the colloidal substance on sensitized and alex- 

 inized corpuscles both of the ox and of the guinea-pig, Ehrlich and 

 Sachs' experiment is readily understood. It may be explained 

 just as the preceding experiments, namely, by supposing that in 

 the mixture of fresh horse serum and heated bovine serum the 



* This mixture containing alexin and corpuscles sensitized simply with heated 

 bovine serum (and not with the specific antiserum) is not sufficiently sensitized 

 or fixed with alexin to bring about an energetic adhesion of the colloid; this latter 

 substance, as we shall later see, under these conditions is somewhat absorbed, so 

 that hemolysis although slight is increased. 



It is to be noted that the weakness of the bovine sensitizer is due perhaps to 

 heat. This substance indeed appears to be more powerful in unheated bovine 

 serum. We find that guinea-pig corpuscles are energetically clumped by fresh 

 serum, which shows that the colloid has adhered; this means, of course, that they 

 have been well sensitized and also alexinized by the fresh bovine serum; hemolysis 

 subsequently occurs. 



