l82 LOCAL TLSSUE REACTIVLFY 



duration ol icadixity may oiler an additional method lor (juan- 

 titati\e estimation ol the pcjtency ol the a( live bacterial jjriiu ijjles. 



FAIK OK ACmVI', l'RINC:iI'I.KS INJECTKD INK) rHI', BLOOD SrKl'AM 



In sexeial groups ol rabbits large amounts ol Ji. /v/;//o,s(/,s ac- 

 tive ])rin( iples (2000 to '^000 reacting iniits per kilo ol l)ody 

 weight) were injected intraxenously. The rabbits Avere bled Irom 

 the heart at various intervals ot time lolhnving this injection. 

 Serum and delibrinated blood obtained Irom rabbits injected 

 with the active princij)les t\\'o, five, txventy-foin-, and forty-eight 

 hours prior to the bleeding were consistently negative for skin- 

 preparatory and reacting factors. A large amount of active prin- 

 ciples was still present, however, in the serum of rabbits bled 

 immediately after the injection of 2000 to 3000 reacting iniits 

 per kilo of body weight. The serum diluted as high as 1:30 was 

 capable of eliciting typical reactions in rabbits prepared with 

 inidiluted B. tyjjJiosus "agar washings" filtrate. The same serimi 

 undiluted xvas capable of eliciting the state of reactivity in rab- 

 bits tested l3y provocative injection of 50 reacting tuiits of B. ty- 

 phosus "agar washings" filtrates. In some experiments the un- 

 diluted serimi containing the B. typJiosus active principles xvas 

 mixed with a neutralizing anti-typhoid horse serum (H. 196) 

 diluted 1:10, 1:20, 1:30, and 1:50. The immiuie serum diluted 

 as high as 1:30 was capalole of neutralizing completely the active 

 principles of the rabbit serum but failed to do so in dilution 1:50. 

 It coidd be concluded from this that the active principles of B. 

 typhusiis injected into the l)lood stream inay be recovered by an 

 immediate heart bleeding. It is also of interest that the B. typhosus 

 active principles thus obtained are apparently identical ^vith those 

 introduced into the blood stream inasmuch as they are specifically 

 neutralized by an anti-typhoid imminie serimi. 



The prompt disappearance of the active principles of the 

 phenomenon from the blood stream suggested a search for these 

 factors in the various organs. After various intervals of time fol- 

 lowing the intravenous injection of a large amount of active prin- 

 ciples, rabbits were killed and various organs removed under 

 sterile precautions. The organs were triturated in 0.85 per cent 

 NaCl solution, suspended in the saline solution in the ])ro})ortion 

 of 1 gm. to 1 c.c, and cenrifuged at a low speed. The supernatant 

 fluid was used for the experiments on the day of its prepara- 

 tion. Spleen and liver extracts, diluted 1:4, of rabbits injected 



