HMMOLYSINS. 43 



animals. This would lead to the possibility of the 

 occurrence of immune bodies, for the same species 

 of blood-cell or bacterium, differing from each other 

 in the partial immune bodies composing them, 

 according to the variety of animals used in prepar- 

 ing the serum. 



MetchnikofFs Views Practical Importance of the 

 Point. This view is directly opposed to that of 

 Metchnikoff and Besredka, who believe that a cer- 

 tain immune body, e.g. one specific for ox blood, 

 is always the same no matter from what animal it 

 is derived. The point is not merely theoretical, 

 but under certain circumstances of great practical 

 importance. If we believe, as Ehrlich does, that 

 the immune body differs according to the species of 

 animal from which it is derived, i.e., that it is made 

 up of different partial-immune bodies, then we must 

 admit that we have better chances for finding fit- 

 ting complements if we make use of immune bodies 

 derived from a variety of animals. We would, for 

 instance, be likely to achieve better results in treat- 

 ing a typhoid patient with a mixture of specific 

 bactericidal typhoid sera derived from a variety of 

 animals than if we used a serum derived only from 

 a horse. For in such a mixture of immune bodies 

 the variety of partial-immune bodies must be very 

 great and the chances that the complements of the 

 human body will find fitting immune bodies, and so 

 lead to the destruction of the typhoid bacilli, are 

 greatly increased. Ehrlich and his pupils have 



