REACTING POTENCY 265 



imuli as the mixtures ^vere highh turbid at the time of injection, 

 it was of interest to determine separately the reacting potency of 

 the precipitate and the supernatant fluid of a centrifiigalized mix- 

 tme. The mixtme consisted of 4 parts of pneimiocfjcciis Type III 

 filtrate anrl 1 j)art of anti-pneumococcus Type III rabbit serinn 

 ])repared in my laboratories. The supernatant fluid \vas totally 

 dexoid of reacting potency xvhilst the actixe principles xvere as- 

 sociated xvith the precipitates formed. In titrations of the reacting" 

 potency of the precipitate carried otit in the manner already 

 described, 1:10 dilution of "standard ttnbidity" stispension was 

 the smallest amotuit gi\ing positi\e reactions. 



Pneimiococciis Type III carbohydrate, kindly supplied to me 

 by Doctor M. Heidelberger, xvas dissohed by addition of N/10 

 NaOH and neutralized by addition of N/io HCl. A dose of 1 

 mgm. of carbohydrate, per kilo of body xveight, produced no 

 effect upon skin sites prepared ^vith B. typJwsus and meningo- 

 coccus "agar washings" fdtrates. Similarly, negative residts were 

 obtained with mixttnes of 1, 2, and 3 mgms., of the carbohydrate 

 in 1 c.c. with pneumococcus Type III antiserinn tmdiluted, and 

 diliUed 1:10 and 1:100 (Shwartzman, 1932/). 



Plant (1934) recorded positive results with combinations of 

 washed autolyzed suspensions of SpirocJieta pallida with homol- 

 ogous rabbit immune sera; and also with mixtures of Spirocheta 

 pallida haptene xvith the immune sera. For preparation of the 

 haptene, xvashed sediment of SpirocJieta pallida culture "was ex- 

 tracted "^vith alcohol, and after evaporation of alcohol the residue 

 xvas taken up in NaCl solution. Wassermann antigen, however, 

 in mixture xvith syphilitic human rabbit serum gave no reactions. 



REACTING POTENCY OF MIXTl'RES OF DETOXIFIED BACTERIAL 

 PREPARATIONS WITH SPECIFIC IMMUNE SERA 



B. typhosus "agar Avashings" filtrates detoxified by addition of 

 formalin (p. 112) undiluted, diluted 1:10, 1:50, and 1:125 ^vere 

 mixed \vith anti-typhoid horse serum. In spite of a considerable 

 amount of precipitate formed, all combinations gave negative 

 results. P. Bordet (1936//) failed to obtain reactions xvith mix- 

 tures of diphtheria toxoid xvith dij)htheria antitoxin. I also failed 

 to obtain reactions xvith combinations of filtrates of B. nieliteusis 

 and Streptococcus viridaiis xvith homologous antisera in spite of 

 a heavy flocculation in the mixtures. 



It is obvious, therefore, that as in the case of combinations of 



