402 INFECTION AND RESISTANCE 



The fact that precipitation occurs when these antibodies are added 

 to the homologous dissolved antigen is merely a secondary colloidal 

 phenomenon. Antigen and antibody react, forming a complex which 

 is then amenable to the action of alexin. Being colloidal in nature, 

 and mixed under suitable quantitative and other conditions which 

 favor flocculation, they precipitate. This point of view, then, identi- 

 fies the so-called precipitins with the protein-sensitizers or albumino- 

 lysins first hypothetically suggested by Gengou. It leads necessarily 

 to the conception that in cytolysis as well as proteolysis, in fact, in 

 all reactions in which antigen is sensitized to the action of alexin, 

 there is functionally but one variety of antibody the sensitizer 

 precipitation and agglutination being incidental physical phe- 

 nomena not dependent upon special antibodies as heretofore sup- 

 posed. 



In this sense, then, the "precipitins" or albuminolysins may be 

 regarded as identical with the anaphylactic antibody. 



That animals in whose circulation antigen and antibody are 

 simultaneously present do not suffer from symptoms of anaphylaxis 

 has been referred by Zinsser and Young 51 as possibly due to the 

 action of a protective colloid which prevents the union of the two. 



THE MECHANISM OP ANTIANAPHYLAXIS 



The conditions under which these animals, previously anaphy- 

 lactic, may be rendered refractory or "antianaphylactic" have been 

 discussed in another place. This condition is not entirely comparable 

 to immunity since it is a purely temporary state, lasting possibly a 

 few weeks, but after this the animals do not return to the normal 

 condition, but gradually become again moderately hypersusceptible. 

 (Rosenau and Anderson Otto and others.) Thus a guinea pig 

 which has been sensitized, then rendered antianaphylactic by a mas- 

 sive injection of antigen, may react with mild symptoms to an in- 

 jection made 20 to 30 days later. Such returning sensitiveness, 

 according to Rosenau and Anderson 52 is usually mild, fatal reac- 

 tions rarely occurring. 



A satisfactory theory of antianaphylaxis has not yet been ad- 

 vanced. 



Besredka, 53 as we have seen, believes that the anaphylactic reac- 

 tion takes place by the union of the toxic factor in the serum (anti- 

 sensibilisin) with a specific antibody sessile upon the cells of the 



51 Zinsser and Young-. Jour. Exp. Med., Vol. 17, 1913. 



52 Rosenau and Anderson. Pub. Health and M. H. S. Hyg., Bull. 3 36, 

 1907. 



53 See Besredka, "Kraus u. Levaditi Handbuch, etc.," Erganzungsband ], 

 p. 246. 



