PHENOMENA FOLLOWING IMMUNIZATION 97 



The substances which possess antigenic properties that is, which 

 give rise to antibody production with the exception of a few isolated 

 and contested cases, are all of them protein in nature. Well-trained 

 chemists have exerted themselves to purify antigenic substances, 

 in attempts to determine the particular fractions of the complex 

 protein molecule upon which the antigenic properties depend. In 

 the course of such work a number of men claim to have obtained a 

 truly antigenic substance which no longer gave protein reactions. 

 The instance most frequently cited is Jacoby's 65 announcement of 

 a protein-free ricin. Jacoby worked with an apparently very impure 

 "Ausgangsmaterial" consisting of commercial ricin, which he di- 

 gested for five weeks in trypsin solution. At the end of this time he 

 obtained a ricin which still possessed the properties of the original 

 castor-bean extract, but no longer gave protein reactions. His "puri- 

 fied ricin," however, was quickly destroyed by further trypsin diges- 

 tion, and more recent work by Osborne, Mendel, and Harris 66 

 appears to have fully refuted Jacoby's results. They found the 

 purified ricin identical with the coagulable albumin of the castor 

 bean, and found that tryptic digestion destroys the characteristic 

 ricin properties. 



Less easily refuted have been the careful experiments of Ford 6T 

 upon the active principle of a mushroom (Amanita phalloides) and 

 upon that of the poison-ivy plant (Rhus toxicodendron) . These 

 substances, he claims, are non-protein. In the case of Amanita 

 phalloides Abel and Ford 68 have shown it to be a glucosid, and 

 similar structure has been claimed for Rhus by Syme. 69 Yet with 

 both of these substances Ford has succeeded in producing specific 

 antitoxins. Rabe 70 has questioned these with Amanita phalloides. 

 He believes that the poison with which Ford worked is not a glucosid, 

 but is of protein nature. In the case of Rhus, however, Ford's con- 

 clusions have not, to our knowledge, been challenged. 



With these and a few other less important exceptions, however, 

 observers have uniformly concluded that antigenic property and pro- 

 tein structure are inseparably associated. All procedures by which 

 proteins have been hydrolized into their simpler fractions, chemical 

 splitting, tryptic or peptic digestion have in every case resulted in a 

 simultaneous loss of protein reaction and antigenic property.. 



Many attempts have also been made to show a relation between 

 antigenic properties and the lipoid constituents of cells. These en- 

 deavors were obviously stimulated by the observation that many li- 



65 Jacoby. Arch. f. exp. Path. u. Pharm., Vol. 46, 1901. 



66 Osborne, Mendel, and Harris. Am. Jour, of PhysioL, 1905, Vol. 14. 



67 Ford. Jour, of Inf. Dis., Vol. 3, 1906 ; Vol. 4, 1907. 



68 Abel and Ford. Jour. Biol. Chem., 1907, 



69 Syme. Johns Hopkins Thesis, 1906. 



70 Rabe. Zeitschr. f. exp. Path. u. Therap., Vol. 9, 1911. 



