RELATIONS OF SENSITIZERS TO ALEXIN. . 381 



(a) Suspension of sensitized corpuscles, 1 c.c. ; fresh horse serum, 

 0.3 c.c. 



(b) Sensitized corpuscles, 1 c.c. ; horse serum, 56 degrees, 0.3 c.c. 



(c) Non-sensitized corpuscles, 1 c.c.; fresh horse serum, 0.3 c.c. 

 Half an hour later the tubes are rilled with salt solution, cen- 



trifugalized and the supernatant fluids decanted; this washing is 

 repeated. After the second decanting 1 c.c. of salt solution plus 

 0.4 c.c. of bovine serum (56 degrees) is added to each sediment of 

 corpuscles. The result is, no agglutination in tubes "6" and "c," 

 but a strong and almost instantaneous agglutination in tube "a." 



Second : We have just said that the colloidal substance is absorbed 

 by sensitized and alexinized corpuscles. If this is true, heated 

 bovine serum that has been treated with such corpuscles should 

 not be able to agglutinate fresh corpuscles. Experiment verifies 

 this expectation. Well-sensitized bovine corpuscles are washed, 

 restored to primitive volume and mixed with three parts of fresh 

 horse serum. Two hours later the corpuscles are washed again, 

 restored to primitive volume and an equal amount of heated bovine 

 serum is added. The bovine serum is found, subsequent to this 

 contact, to retain little if any of its colloidal substance.* 



Third : Bovine serum that has lost the greater part of its colloidal 

 substance in this manner should show very much less activity than 

 intact serum when mixed with fresh horse serum and guinea-pig 

 corpuscles. We find, indeed, that agglutination and hemolysis 

 of these corpuscles are very much less in the presence of this ex- 

 hausted serum than with a corresponding dose of untreated bovine 

 serum or with bovine serum that has been treated simply with 

 guinea-pig corpuscles and has thereby lost its sensitizer only. 



Fourth: The colloidal substance is absorbed and produces 

 agglutination only when the corpuscles are alexinized as well as 

 sensitized. In the Ehrlich and Sachs' experiment it is evidently 

 horse serum that furnishes the alexin. We should expect, then, that 

 if, to a mixture of guinea-pig corpuscles and heated bovine serum, 

 horse serum that has been treated with any sensitized corpuscles 



* It is to be noted that very small amounts of colloidal substance suffice to 

 agglutinate sensitized and alexinized corpuscles. A complete removal of the 

 colloidal substance would therefore be necessary to bring about an entire loss of 

 agglutinating property. 



