64 IMMUNITY 



istration. The skin eruptions, joint pains and edema of serum 

 sickness are also evidences of this condition. It is said that those 

 persons who suffer after anti-toxin are susceptible to the emana- 

 tions from horses and the physician should make inquiries in this 

 direction when contemplating the injection of all sera. 



In experimentally induced hypersusceptibility the reaction is 

 specific. The condition is transmissible from mother to foetus 

 and it can be transferred from adult to adult passively by injecting 

 the blood of a sensitive animal into a normal one. The first dose 

 is called the sensitizing one, the second the intoxicating. The 

 incubation period of the sensitization varies with the nature of the 

 protein; for horse serum it is from eight to twelve days, for bac- | 

 terial proteins from five to eight days. The sensitive period may j 

 last for several years. In searching for the cause of this reaction 

 it was found that there are (i) a spastic distention of the pul- 

 monary alveoli probably both of central and local nature, (2) 

 scattered hemorrhages in the organs and (3) hemorrhages with 

 ulcerations in the gastric mucosa. There have been many theories 

 for this phenomenon, but those of Vaughan, Friedberger and Wolff 

 Eisner may be condensed and compounded about as follows. The 

 body is unprepared to care for parenterally (otherwise than gastro- 

 intestinal tract) introduced protein and must develop anti-body 

 or enzyme to care for it. This enzyme or anti-body works slowly 

 and carefully disposes of the foreign protein, the products of which 

 are slowly absorbed and removed. In accord with the overpro- 

 duction theory this anti-substance is in large quantity when an- 

 other introduction of protein occurs, and goes to its work with 

 avidity so that it rapidly breaks the protein up into toxic elements 

 which cannot suddenly be cared for by the body. It is also 

 thought by some workers that the body protein of the animal in 

 question is attacked and split, liberating toxic fractions, since the 

 injected protein would not be adequate in amount to accomplish 

 poisoning. These protein toxins attack nervous and parenchy- 

 matous tissues. Another very plausible theory would have it 



