REACTING POTENCY 269 



lated agar (0.12 })er cent) in 0.85 per cent salt solution, shred 

 agar (0.12 per cent) in 0.85 per cent salt solution, granulated 

 agar (0.2 per cent) washed in water, ether or alcohol and sus- 

 pended in 0.85 per cent salt solution were injected, the character- 

 istic area of hemorrhagic necrosis at the site of intracutaneous in- 

 jection of toxic filtrate developed. The usual dosage given was 3 

 c.c. without reference to the weight of the animals. Heating of the 

 material in the autoclave for 40 minutes apparently did not 

 change the abilit.y^,to induce;tiie phenomenon. 



Sickles made an attempt to purify the agar by the. method of 

 Fellers. The agar was dissolved in water in the autoclave. After 

 the treatment with acetic ^id it coidd not be made to gel again. 

 The alcoholic precipitate, of this solution ^vas readily soluble in 

 water. No reactions were obtained in rabbits prepared Avith men- 

 ingococcus Group I "agar washings" filtrates when tiie agar dis- 

 solved after acid treatment -was injected intravenously. The 

 solution of the alcoholic })recij)itate also failed to induce any reac- 

 tions in rabbits prepared ^\ith meningococcus Groups I and III 

 filtrates. 



Phenolized salt solution \vashings of miinocidated bottles of 

 the mediiuu used in the production of meningococcus toxic fil- 

 trates were centrifugal ized and filtered according to the proce- 

 dure follo^ved ^vith the cidture ^vashings. Rabbits ^vere given 2 

 or 3 c.c. doses of the miinocidated medium, intra\enously, 

 twenty-foiu" lioius after an intracutaneous injection of Ciroup I 

 or III meningococcus filtrate. No reaction Asas noted fi\e hours 

 after the intravenous injections. Sickles, therefore, concludes that 

 it seems improbable that the appearance of positive reactions due 

 to the aoar on which the oroanisms were s:rown ^vould cause am- 



o DO 



biguous results in neutralization tests of bacterial toxic filtrates 

 with immune serum by means of the phenomenon. 



In my recent experiments only irregular reactions were ob- 

 tained u'ith large doses of agar obtained from \arious sources. 

 No explanation has been found as yet for this irregularity. 



Freund and Hosmer (1935) employed starch as a reacting lac- 

 tor. Rabbits ^vere prepared by intradermal injections of meningo- 

 coccus filtrate. The intracutaneous injection was followed the 

 next day by an intravenous injection of 10 c.c. of 10 per cent 

 starch solution. In spite of the large amounts used, reactions 

 could not be produced regularly in all rabbits tested. It seemed 



