REACTIVITY TO VARIOUS MICROORGANISMS 43 



crystal borax, 84 gms. boric acid, 99 gnis. NaCl dissolved in 16 

 liters of distilled water) containing 0.4 per cent phenol, using 

 5 c.c. of the solution iov each bottle. The bacterial snspension Avas 

 centrifnged at once at high speed initil clear. The snpernatant 

 fluid was filtered through a Berkefeld "V" filter and tested for 

 sterility and when foiuid to be sterile, injected into rabbits. 



In recent experiments of Koplik (1934) in my laboratories, 

 there ^\as employed brain medium prepared essentially according 

 to the method of Toomey and McClelland (1933) with vari- 

 ous peptones (neopeptone, proteose-peptone (Difco) , \\' itte's pep- 

 tone) . The H-ion concentration ^vas adjusted either to pH 7.3 

 or 7.8. The media were seeded ^vith t^venty-four hour old cultures 

 on chocolate agar slants. The strain used was subctiltured for 

 at least three successive days preceding these inoculations. 



Berkefeld filtrates of four, seven, and seventeen day old brain 

 medium cultures ^vere tested in rabbits for the elicitation of the 

 phenomenon. Twenty-five c.c. of undiluted filtrate ^vere injected 

 intradermally into rabbits and followed in t^venty-four hours by 

 a single intravenous injection of the same filtrate undiluted or 

 in varying dilutions. Comparative studies of the brain cidture fil- 

 trate with chocolate agar culture washings Avere made. The re- 

 stilts were described by him briefly as follows: 



It was possible to elicit the phenomenon under discussion in 

 prepared rabbits by an intravenous injection of the brain filtrate 

 in dilutions ranging from 1:40 to 1:400 and recently 1:1500. 

 Some of the brain media culture filtrates when retitrated two to 

 four months after preparation, showed a rise in efiiective titer of 

 5-20 fold. 



The optimum incubation period for brain medium cultures 

 seemed to be about seventeen days, ^vhile four and seven day 

 cultures yielded filtrates of lower potency. No differences ^vere 

 noted with the various hydrogen-concentrations in the range em- 

 ployed (6.8 to 7.8) . Neopeptone and proteose-peptone (Difco) 

 appeared superior to Witte's peptone. 



Witebsky and Salm (1937) found that the phenomenon could 

 be also produced by intradermal and intravenous injections of 

 suspensions of live cultures of B. influenzae on Levinthal 

 medium and suspensions killed by heating at 60° c. for one hour. 

 Similarly, B. typJiosus "agar washings" filtrates elicited reactions 

 in skin sites prepared with heat killed B. itifJuenzae whilst no re- 

 actions were obtained in sites prepared \vith B. pertussis. Con- 



