ROLE OF INFLAMMATION l8l 



described later, siimiltaneous intra\en()u,s and intradermal injec- 

 tions may bring about inhibition ol the phenomenon (Ogata, 

 H)']6) (p. 337) . The reactions occurred irregularly and alter a 

 prolonged period of time, i.e., approximately twenty hours in- 

 stead of the customary loin- hours. The explanation suggested is 

 that the pro\ocati\e factors persisting in the blood stream pro- 

 duce the reaction after the lapse of the necessary incidjation 

 period for elicitation of the state of local reactixity, this being 

 responsible for the delayed reaction. The inhil)ition of the phe- 

 nomenon described by Ogata requires the employment of an 

 amount of preparatory factors smaller than that employed in the 

 experiments just described, and, therefore, the residts do not 

 offer a discrepancy. 



The incubation period necessary for the elicitation of the state 

 of reactivity and the diuation of the state of reactivity induced 

 has not received any detailed investigation as yet. As noted in 

 the introductory chapter, the optimum interval between the txvo 

 injections is txventy-four hours. The state of reactivity may be 

 induced, hoxve\er, in shorter intervals of time as well, although 

 more irregularlv than after an interval of twenty-four hours. As 

 a rule, inter\als less than six hours are inadecpiate, although pos- 

 sibly, exceptions may be noted. Thus, Gratia and Linz (1932c) 

 found that occasional reactions may also be obtained after a six 

 hour incubation j^eriod. 



The duration of local skin reactivity to bacterial fdtrates de- 

 pends a great deal on the amoiuit of the material used for the 

 preparation and also on the potency of the preparation. The 

 state of reactivity induced by B. tyljJwsus tryptic digest broth cul- 

 ture and plain broth cultures as weW as filtrates partially destroyed 

 by exposures to certain temperatiues, elicit a state of reactivity 

 wliich ordinarily does not last more than forty-eight hours. Skin 

 sites prepared -with B. Ixphusiis "agar washings" hltrates ordinar- 

 ily of higher potency than broth culture hltrates, retain their 

 reactivity for seventy-t^vo hours. The longest state of reactivity is 

 obtained by employing meningococcus "agar washings" filtrates. 

 It may last for a period as long as ninety-six hoins and occasion- 

 ally for one hundred and tAventy hours. The duration of reactiv- 

 ity may be correlated, to a fair degree of accuracy, Avith the 

 j^henomenon-producing potency of the filtrate as determined bv 

 titrations described in Chapter i, and therefore, studies on the 



