266 LOCAL TLSSUE REACTIVITY 



non-bacterial anti^^cMis witli homologous antibodies, the })olency 

 of niixtmes of bacterial antigens with antibodies is conditioned 

 by a toxic quality, unknown as yet, of the ingredients l)ul not Ijy 

 the mere formation of the precipitates. 



Further in\estigations remain necessary in order to explain the 

 following apparent discrepancy. As is seen, certain inactive bac- 

 terial filtrates may be rendered toxic by addition of homologous 

 antisera. Conversely, active filtrates when detoxified by formalin 

 do not yield reacting factors on addition of homologc:)us antisera. 

 The explanation which suggests itself is that the antigen-|-antibody 

 interaction merely liberates a toxic cjuality of the ingredients 

 which, althotigh present in the inactive preparations, remains in- 

 hibited by some unknown effects. Formalin, however, aj^parently 

 completely destroys this toxic quality. 



REACTING POTENCY OF MISCELLANEOUS ANTIGENS WITH 

 HOMOLOGOUS ANTISERA 



Negative results ^vere obtained by me ^vith mixttnes of Rovis 

 sarcoma extracts and filtrates ^vith sera of chickens bearing Rous 

 sarcoma for periods of one to ten \veeks; and with mixtmes of 

 human and monkey poliomyelitis virus with convalescent sera. 

 Plaut (1934) could not elicit any reactions ^vith a mixture of 

 alcoholic extract of brain tissue ^vith rabbit anti-brain serum and 

 P. Bordet (1936/;) failed to j^roduce reactions with beef red blood 

 cells sensitized by means of rabbit and anti-beef hemolysins. 



SKIN-PREPARATORV POTENCY OF PRECIPITATES AND SUPERNATANT 

 FLUIDS DERIVED FROM ANTIGEN-^ANTIBODY MIXTURES 



It has l)een already pointed out in Chaj)ter vi that normal and 

 immune animal sera, as well as combinations of sera ^vith homol- 

 ogous antisera, are totally devoid of skin-preparatory potency. 

 When it Avas discovered that the antigen-)-antibody combinations 

 possess reacting factors, they ^vere also tested for their skin-prepara- 

 tory potency. The prej:)arations tried 'were mixtures of human 

 sertmi with anti-human horse serum, and precipitates and super- 

 natant Huids deri\'ed from these mixtures. Fach rabbit ^vas pre- 

 pared by a single intradermal injection of 0.25 c.c. of the prepara- 

 tion tested and twenty-four hours later injected intravenously -^vith 

 50 B. tyjjJiosus reacting units. The results, Avhich rejnesented 

 readings of 3 smviving rabbits for each preparation tested, were 

 entirely negative. 



