164 IMMUNE SERA 



intraperitoneal, or intravenous introduction of alien 

 proteid is followed by the formation of antibodies; 

 at the same time it can readily be shown that no 

 antibodies develop after the oral introduction of 

 milk, eggs, or even of raw meat. In other words, 

 there is a marked contrast in the behavior of the 

 body between the enteral and the parenteral intro- 

 duction of proteid. In the former the proteid is 

 acted on by the gastric and intestinal juices (pepsin, 

 trypsin, and enterokinase) . These so break down 

 the proteid molecule that it loses its species identity. 

 After this, absorption takes place, and with it there 

 is a synthesis, or rearrangement, of the molecule 

 whereby it is built up into the specific proteid of 

 the body. Under normal conditions it is im- 

 possible to produce specific antibodies by feeding 

 alien proteid. Precipitins have, however, been pro- 

 duced by overfeeding animals with large quantities 

 of alien blood. When proteid is introduced paren- 

 terally it gives rise to the formation of specific 

 antibodies, and thus to the state of anaphylaxis. 

 The term anaphylaxis is unfortunate, for the con- 

 dition is not always opposed to immunity. Von 

 Pirquet, it will be remembered, called attention to 

 the altered reactivity during the anaphy lactic state. 

 We must not lose sight of the fact that the symp- 

 toms of anaphylaxis are brought on when sensitized 

 animals are subsequently injected 'with relatively 

 large quantities of the same proteid. Following 



