302 INFECTION AND IMMUNITY 



we may at present dismiss with a few words as interesting developments 

 in the theoretical study of anaphylaxis but, since then, proved to be 

 of little importance in the actual understanding of the phenomena. 

 Many of these earlier theories were made possible by lack of sufficient 

 evidence that anaphylaxis depended upon the reaction between an anti- 

 body and its antigen and upon attempts to show that the substance 

 which was sensitized was not the same as that which produced the toxic 

 symptoms on reinjection. This last opinion was mainly based upon 

 such experiments as those of Besredka which seemed to show that the 

 toxogenic was less heat stable than the sensitizing substance, but since 

 the amount which sensitizes need be only anywhere from 1-1 00th to 

 l-1000th part of the amount required for the production of toxic symp- 

 toms, as Wells and others have calculated, it is plain that this was the 

 explanation for the apparent difference in heat stability between the 

 two. Chemical differentiation between the two substances, as attempted 

 by Gay and Adler, has likewise failed to hold good. We have now come 

 to the recognition that anaphylaxis is the result of the presence of spe- 

 cific antibodies in the animal into which the antigen is injected. These 

 antibodies can be produced on the one hand by a preliminary injection 

 of the antigen, thus stimulating the animal to produce its own anti- 

 bodies, or by the direct injection of the antibodies from another animal 

 as in passive sensitization with immune serum. 



The development of antibodies in the animal then alters the reaction 

 capacity of the animal for the particular antigen employed. This is 

 the state which v. Pirquet has named "allergic," and it is this allergie 

 or changed reaction-capacity due to the formation of antibodies, whether 

 circulating or, as is more probable, attached to the cells themselves, 

 which induces in the animal the anaphylactic state. 



It is by means of the passive method of sensitization that the relations 

 between anaphylaxis and antibodies have been most successfully stud- 

 ied. Doerr and Russ 1 showed that the power of a serum to convey 

 anaphylaxis passively depended directly upon its contents of specific 

 antibody. It was then shown by Nicolle, 2 Otto, 3 and others, that a 

 sharp reaction can be produced by this method only when a distinct 

 interval not less than 4 to 6 hours, was allowed to lapse between the 

 injection of the antibodies and the injection of the antigen. This may 



1 Doerr and Russ, Ztschr. f. Immunitatsforsch., 1909, iii. 



2 Nicolle, Bull, de llnst. Past., 1907, v. 



3 Otto, Das Theobald Smithsche Phaenomenon, etc., von Leuthold Gedenkschriftv 

 1905, i. 



