HYPERSUSCEPTIBILITY 217 



phylaxis may be demonstrated about four hours after intravenous 

 administration of the serum from the hypersusceptible animal, about 

 twenty-four hours after intraperitoneal injection and from twenty-four 

 to forty-eight hours after subcutaneous administration. It remains 

 at its height for about three or four days, gradually disappears in a 

 few weeks and never exhibits the permanence of active anaphylaxis. 

 Further study by numerous investigators has shown that passive ana- 

 phylaxis arises as the result of injection of serum from an animal in 

 the hypersusceptible state or from an animal in the " incubation " 

 period before sensitization can actually be demonstrated ; it may also 

 follow the injection of the serum of an animal in the anti-anaphy lactic 

 state and may be produced by the injection of an immune precipitating 

 serum. In the last-named instance an animal is immunized to the 

 particular protein for which passive anaphylaxis is to be produced. 

 Doerr and Moldovan pointed out this fact, and it has been repeatedly 

 confirmed. Scott demonstrated that the intensity of the anaphylactic 

 shock parallels the titer of the precipitating serum. The young of 

 sensitized female guinea-pigs are sensitive, as has long been known. 

 The recent work of Reinals confirms this fact, but does not definitely 

 settle the question as to whether the sensitization of the young is active 

 or passive. 



Specificity of Anaphylaxis. That the process is specific was 

 pointed out by the earliest investigators. It is undoubtedly one of the 

 most specific of the biological reactions, as is emphasized by its extreme 

 delicacy in regard to sensitizing dose. Nevertheless, group reactions 

 appear as in the reactions of immunity. For example, a guinea-pig 

 sensitive to sheep serum will react somewhat less violently to goat 

 serum. Wells and Osborne have shown that cross reactions occur 

 between gliadin from wheat and rye, and hordein from barley. The 

 reactions, however, are strongest with the homologous protein. Never- 

 theless, Wells was able to separate ovovitellin and crystallized egg-white 

 by the anaphylaxis reaction and is of the opinion that where group 

 reactions occur the reactions are the result of common groups in the 

 protein molecules even though the proteins may appear to be chemi- 

 cally distinct. If guinea-pigs are sensitized to several proteins simul- 

 taneously they will react to any of the proteins employed, but after an 

 animal has reacted to one of the proteins, subsequent reactions to the 

 others are less severe. Investigations conducted in this laboratory with 

 serum proteins indicate that although desensitization is best produced 

 by homologous sera it may be effected by biologically-related sera and 

 by non-related sera. For such purposes considerably larger doses of the 

 heterologous sera are necessary than of the homologous serum. Against 

 the assumption that desensitization indicates the specificity of the reac- 

 tion is the fact claimed by Banzhaf and Steinhardt that lecithin protects 

 against anaphylactic shock. Rosenau and Anderson failed to confirm the 

 work of Banzhaf and Steinhardt, but it may well be that a colloidal dis- 

 turbance of some sort may prevent the appearance of shock and that 



