REACTING POTENCY 289 



e\|)ci iiiiciits {lcs{iil)e(l here, tlie injection ot bacterial filtrates 

 ])ri()r to the test with horse sernni or iollowing it, ^vas substituted 

 bv the abo\e antit^en-j-antil^ody mixtines of ascertained reacting" 

 potency. No reactions residted in these experiments. 



EFFECT OF BACTERIAL FU.TRATE.S INJECTED INTRAVASCUEARLY UPON 

 SKIN SITES TESTED WITH HORSE SERUM IN RABBITS SENSITIZED WITH 



HORSE SERUM 



Tt is desirable to mention liere the following incidental ob- 

 ser\ations: 



In the ^vork described thus far, single sites were tested intra- 

 dermal ly with horse serum. In the following experiments, rab- 

 bits sensitized to horse seriun recei\ed simultaneously t^vo intra- 

 dermal injections of horse serum. Bacterial filtrates were injected 

 prior to and following the test injections ^vith horse serum. 



The intravenous injection of 25 B. typhosus reacting tuiits, 

 per kilo of body ^veight, preceded these tests by one hour. No 

 reactions were obtained, ^vhilst positive reactions were produced 

 in sites of single tests of other^vise similar experiments. 



Two simultaneous injections of horse serum preceding the in- 

 jection of bacterial filtrate by f^venty-four hours, yielded reac- 

 tions similar to the single site tests. This incidental obserxation 

 is possibly related to some process of local desensitization to the 

 anaphylactic reaction xvith horse serum (Shwartzman, 1936c) . 



EFFECT OF IN VIVO INTERACTION OF ANTIGENS WITH ANTIBODIES 

 UPON SKIN SITES INFECTED WITH B. C. G. 



Inasmuch as it Avas shown that bacterial and virus infections 

 are capable of inducing the state of reactivity to bacterial fil- 

 trates, it was deemed important to determine whether B. C. G. 

 infected skin sites could react with the antigen-j-antibody com- 

 jjlexes. In these experiments rabbits were sensitized to horse 

 serum and received one or several intradermal injections of 

 B. C. Ci. After various intervals of time following the inoculation 

 of B. C. G., they xvere injected intravenously xvith horse serum. 

 The B. C. G. undoubtedly could react with the antigen+antibody 

 complexes, the success being conditioned apparently by various 

 factors not closely studied as yet, i.e., the dose of B. C. G. em- 

 ployed, the time interval between the injection of B. C. G. and the 

 test injection xvith horse serum, etc. It appears, for instance, that 



