'74 LOCAL ILSSLIE REACTIVITY 



fold increase in reacting potency per milligram ul dr)' \veight and 

 ol nitrogen. 



B. coU gr()^vn in fluid synthetic meditim was most readily pini- 

 fied: thus, the decrease in total dry weight and nitrogen, 9'^ and 

 89 per cent respectively, was greater than in any of the other fil- 

 trates. Similarly, the increase in activity per milligram of dry 

 weight and of nitrogen, 750 and 452 per cent respectively, was 

 also the highest. When a similar jjreparation was concentrated 

 in vacuo to one-half of its original volimie, approximately the 

 same amoinit of total solids and nitrogen was removed by dialysis, 

 but the increase in activity was only 234 and 175 per cent, respec- 

 tively. Apparently, therefore, the concentration /// xxiciio may con- 

 siderably reduce the extent of pmification. 



With B. typhosus, where a good purification was also obtained, 

 a slightly greater removal of total solids and nitrogen was ob- 

 tained in filtrates of cultures on synthetic medium agar than on 

 veal infusion agar. Although the actual reacting titers of menin- 

 gococcus ctdtiue filtrates were decidedly the highest, both before 

 and after dialysis, the extent of ptnificaticjn attained by dialysis 

 was lower than in any of the other filtrates. Thus, the percentage 

 increase in activity in these filtrates was only 70 per cent per milli- 

 gram of nitrogen and 136 per cent pei" milligram of dry weight. 

 Possibly, the use of 1 per cent rabbit's blood in the inociUinn, 

 carried over into the washings, accounts in piivi lor the relatively 

 lower figures. It shoidd be noted, ho^vever, that the highest nimi- 

 ber of reacting tmits per milligram of nitrogen and dry weight 

 was observed in the dialyzed meningococcus filtrates. By calculat- 

 ing the reciprocals of these values, it ^vas foimd that 0.0067 n^iHi- 

 grams of total solids and 0.00087 milligrams of nitrogen were 

 capable of eliciting the reaction in prepared skin sites at the 

 end-point. 



Biunet (1931) made the observation that filtration of the ac- 

 ti\e princijiles through a Seit/ filter resulted in a great decrease 

 in the potency. This observation Avas confirmed in my laboratory 

 on a number of occasions. Filtration tiirougji lierkefeld "\^" can- 

 dles yields acti\'e jDrejiarations although it is suggestive that some 

 of the activity is lost by the filtration. 



Boquet (1935), Gratia and Linz (i932r), P. Bordet (1935), 

 Alechinsky (1936), and Aitoff, Dion and Dobkevitch (i936<7) 

 obtained active preparation by filtration of the cultures through 

 Chamberland L2 and L3 candles. 



