REACTING POTENCY 279 



can be obtained in rabbits Avhich are not ready as yet for the 

 Arthus phenomenon. 3. Skin preparation with a bacterial filtrate 

 of ascertained skin-preparatory potency is essential. 4. The reac- 

 tion is limited to the prepared skin site. 5. The antigen-|-antibody 

 interaction has to take place in the blood stream (Shwartzman, 



EFFECT OF REACTING FACTORS FORMED IN VIVO UPON SKIN SITES 

 PREPARED BY NON-BACTERIAL FACTORS 



Here again, the essential role of bacterial filtrates for prepara- 

 tion to tlie phenomenon became obvious. 



Thus, no reactions Avere obtained when rabbits were injected 

 intradermally cither ^vith the sernm precipitinogen or the pre- 

 cipitating antisermn and after varions inter\als of time reinjected 

 intiaxenoiisly with the precipitating antiserum in the case of the 

 former, and with the serum precipitinogen in the case of the 

 latter. Moreover, ^vhilst mixtures of serum precipitinogen Avith 

 precipitating antiserum injected intravenously elicited se\ere 

 hemorrhagic necrosis in skin sites prepared '^vith potent bacterial 

 filtrates, they had no effect upon sites prepared either ^vith the 

 precipitinogens or the precipitins. Also, an intravenous injection 

 of horse serum into rabbits actively sensitized to the serum pro- 

 duced no effect either upon areas in ^vhich there ^vas induced 

 inflammation with turpentine, or in areas prepared ^vith horse 

 serum. Thus, the experiments clearly sho^ved that the antigen-f- 

 antibody interaction elicited in the manner described, while pro- 

 ducing no effect upon normal, sensitized and inttamed tissues, 

 was responsible for severe injuries to tissues prepared ^vith bac- 

 terial filtrates. 



EFFECT OF INTRADERMAL REINJECTION OF ANTIGEN-[-ANTIBODY 

 MIXTURE INTO SITES PREPARED WITH BACTERIAL FILTRATES 



There remained the question ^vhether the antigen-^antibody 

 interaction taking place outside the blood stream would also 

 bring about a similar injurious effect upon skin sites prepared 

 with bacterial filtrates. 



Rabbits each recei\ed a single intradermal injection of 0.25 c.c. 

 of undihited B. typhosus "agar ^vashings" filtrate. Twenty-foiu" 

 hours later the same areas were eacli reinjected Avith 0.5 c.c. of a 

 mixture consisting of one part of anti-human horse serum and 

 one part of human serum diluted 1:4. The same mixture was 



