372 INFECTION AND RESISTANCE 



would expect here, as in other serum reactions, a certain limitation 

 in the degree of specificity, and Otto recommends the less delicate 

 subcutaneous method of testing for all experiments in which ques- 

 tions of specificity are involved. This point we will touch upon a 

 little later. 



An interesting addition to our knowledge of such specificity was 

 made by experiments of Rosenau and Anderson, 38 which showed that 

 a guinea pig could be rendered sensitive at one and the same time 

 to blood serum, eggwhite, and milk, reacting specifically to each on 

 second injection. 



In anaphylaxis, again analogous to antibody reactions in general, 

 the specificity, as a rule, is one of species. In other words, the pro- 

 tein of any animal is specific for the proteins of its particular spe- 

 cies generally, there being definitely similar characteristics in the 

 body proteins of animals of like species which, though chemically 

 indefinable, are nevertheless delicately determinable by biologic reac- 

 tions. In considering specificity of precipitins, however, we have 

 seen that there are exceptions to the specificity of species expressed 

 in the phenomenon of so-called organ specificity. The same* thing 

 has been shown for anaphylaxis. Kraus, Doerr, and Sohma 39 were 

 able to show that animals sensitized with protein from the crystalline 

 lens were hypersusceptible to lens protein generally, whether this 

 came from the species from which the original lens was taken, or 

 whether some other variety of animal had furnished it. On the other 

 hand, animals so sensitized, while hypersusceptible to lens protein 

 generally, did not react to injections of homologous blood. 40 In 

 other words, this organ contains a characteristic variety of antigen 

 (protein) peculiar to this kind of organ throughout the different 

 animal species, but not common to other tissues and organs of the 

 same animal. Results similar to these were obtained by von Dun- 

 gern and Hirschf eld 41 in the case of testicular protein, although 

 here the phenomenon seemed to be less rigidly organ-specific than 

 in the preceding case. These writers worked not with the systemic 

 anaphylactic reaction, but with the localized (allergie) reaction, 

 described above as the phenomenon of Arthus. They injected ex- 

 tracts of the testicular materials into the ears of rabbits and inci- 

 dentally made the very curious observation that pregnant females 

 would not infrequently react to a first injection without previous 

 Bensitization. 



Of great importance also in connection with the subject of organ 



38 Rosenau and Anderson. Jour. Inf. Dis., Vol. 4, 1907. 



39 Kraus, Doerr, and Sohma. Wien. klin. Woch., No. 30, 1908. 



40 Andrejew. Arb. a. d. kais. Gesundh. Amt., Vol. 30, 1909. 



41 Von Dungern and Hirschfeld. Zeitschr. f. Immunitatsforschung, 4, 

 1910. 



