RELATIONS OF SENSITIZERS TO ALEXIN. 385 



pig corpuscles, and the property would become more energetic if 

 one added in addition heated bovine serum. 



To make the experiment more demonstrative, the bovine serum 

 may first be deprived of its sensitizer for guinea-pig corpuscles by 

 contact with them; in this case its action is due entirely to its col- 

 loidal substance, the sensitizer being furnished by the horse serum. 



Under these conditions a mixture of guinea-pig corpuscles, 

 bovine serum (56 degrees) that has been treated with an equal 

 volume of guinea-pig corpuscles, fresh horse serum that has been 

 treated with an equal volume of sensitized bovine corpuscles, and 

 guinea-pig alexin, gives a marked hemolysis. 



Proper controls show that, in this experiment, if bovine serum is 

 not present the hemolysis by the treated horse serum plus guinea- 

 pig alexin is much slower, and also, in another control, that, if horse 

 serum is not present, treated bovine serum plus alexin from the 

 guinea-pig produces no hemolysis. 



Eighth : One final remark on the hemolysis of guinea-pig corpuscles 

 by heated bovine serum plus guinea-pig alexin occurs to us. It 

 is evident that in such a mixture the colloidal substance may take 

 a certain additional part, inasmuch as the corpuscles are some- 

 what sensitized by the bovine serum, and therefore capable of fixing 

 the alexin and subsequently of absorbing a certain amount of colloid. 

 This latter substance, as we know, tends to increase hemolysis. 



Under these conditions the corpuscles should be more actively 

 destroyed than when they have been first sensitized by addition of 

 bovine serum and then washed and guinea-pig alexin subsequently 

 added. If we proceed in this manner we suppress the colloid 

 absorption by sensitized and alexinized corpuscles. In other words, 

 we find experimentally that hemolysis is better when the bovine 

 serum is left with the corpuscles and the alexin than when added 

 to the corpuscles, and the excess eliminated before the fresh guinea- 

 pig serum is added. 



Of course no such peculiarity occurs in the hemolysis of corpuscles 

 in presence of alexin and horse serum. This latter serum, as we 

 know, acts only as a sensitizer and shows none of the properties of 

 the bovine colloid. 



The interpretation of Ehrlich and Sachs' experiment that we 

 have offered is therefore experimentally confirmable. There is, 



