RELATIONS OF SENSITIZERS TO ALEXIN. 387 



For example, hemolysis is much more rapid in a mixture of 1 c.c. 

 of 5 per cent guinea-pig blood plus 0.3 of a cubic centimeter of 

 heated bovine serum plus 0.3 of a cubic centimeter of horse serum 

 plus 0.3 of a cubic centimeter of fresh guinea-pig serum than when 

 the guinea-pig alexin is omitted. In the first instance the agglu- 

 tination is little or none, whereas in the second it is strong. 



Hemolysis and agglutination, therefore, are not inseparable and 

 interdependent, but are two distinct results of a single phenomenon, 

 namely, the absorption of the colloid by sensitized and alexinized 

 corpuscles. 



CONCLUSIONS. 



1. As we know from Ehrlich and Sachs' experiment, guinea- 

 pig corpuscles are hemolyzed by a mixture of fresh horse serum and 

 heated bovine serum (56 degrees), but they resist hemolysis when 

 they are treated first with bovine serum, and the horse serum is 

 subsequently added. The interpretation of Ehrlich and Sachs, 

 which supposes that the sensitizer in bovine serum will not unite 

 with corpuscles until it has first combined with the alexin, is inex- 

 act. In the first place the more powerful and necessary sensitizer is 

 not in the bovine serum, but in the horse serum. Both these sensi- 

 tizers, moreover, act as do other sensitizers in that they do not need 

 alexin in order to unite with corpuscles. In their interpretation, 

 moreover, Ehrlich and Sachs make no mention of an essential factor 

 which gives rise to the remarkable and peculiar appearance of the 

 hemolysis in question. 



2. This factor is a substance present in bovine serum that 

 resists heat to 56 degrees and may be kept for some time. It is 

 colloidal in nature, and is doubtless some albuminous substance 

 which has the property of uniting with corpuscles that are laden 

 with sensitizer and alexin and which remains free in the presence of 

 normal or of simply sensitized corpuscles. This explains why the 

 guinea-pig corpuscles not only are destroyed by a mixture of the 

 two sera, but the reason of their agglutination in voluminous masses. 



3. The absorption of this colloid by sensitized and alexinized 

 corpuscles is probably due to molecular adhesion due to a change 

 in the corpuscles brought about by the two substances with which 

 they have been treated. If both sensitizer and alexin are present, 



