34 I-OCAI, TISSliE REACTIVITY 



which the stock cultures weic niaintained in the hihoiatoiy had 

 no ic'lalioii to the potency ol the active ])riii(i|)les jMochiced. 

 Variations in {potency Aseic lound ainc)n<> (Hrterent strains of the 

 same group and in various lots ot filtrates. The incidental observa- 

 tion which seems worthy of mention is that maintenance of men- 

 ingococcus strains on egg medimn may bring about occasional 

 loss of ability to produce active principles. 



Whilst the efficiency of meningococcus "agar washings" filtrates 

 was repeatedly corroborated by a large group of ^vorkers 

 (Sickles, 193^5; Powell and Jamieson, 1931; Pabst and Branham, 

 1933; Apitz, 1935/^; Witebsky and Neter, 1936) , others (Burnet, 

 1931; Malcolm and White, 1932; and Riley and Wilson, 1932) 

 studied the potency of materials prepared t^y a variety of methods, 

 i.e., autolyzed cultures of Besredka (1906) ; defatted meningococ- 

 cus antigen; heated antigens; antigens treated with alkaline and 

 acids; washed suspensions of meningococcus cells, etc. Although 

 no quantitative determinations of the active principles were 

 made with the latter grotip of materials, it is suggestive that all 

 these pre])arations. \vith the exception of washed cells, possess a 

 certain amotmt of actixe j^rinciples. 



ACTIVE PRINCIPIF.S OF CiONOCOCCUS 



In my early experiments I succeeded in reproducing the phe- 

 nomenon of local skin reactivity to gonococcus with filtered saline 

 washings of stock strains of gonococcus grown on North medimn, 

 liver hormone agar pH 6.8, and ascitic fluid 1 per cent glucose 

 agar pH 7.2. The suspensions were centrifuged at high speed and 

 filtered through Berkefeld "V" candles. Rabliits prepared by a sin- 

 gle intradermal injection of 0.25 c.c. of the undiluted material 

 developed severe reactions following the intravenous injection of 

 1 c.c. of filtrates diluted as high as 1:25. ^^ fmther \vork was 

 done in order to select the method of choice. The preparations 

 were stable and were acctnately titrated to the end-point by Klein 



(1933) in my laboratories, for his neutralization studies, described 

 in a later chapter. 



It is interesting that several batches of gonococcus \accines 



(New York City Board of Health) , Avhich were washed cell sus- 

 pensions killed by heat, failed to elicit the phenomenon Avhen 

 used undiluted for intradermal and intravenous injections, i.e.. 

 in quantities at least twenty-five times larger than those neces- 



