Chapter III 



PHYSICO-CHEMICAL PROPERTIES OF THE 



ACTIVE PRINCIPLES OF THE PHENOMENON 



OF LOCAL SKIN REACTIVITY 



THE EFFECT OF HEAT UPON THE ACTIVE PRINCH'LES 



THE question of heat resistance of the active principles of 

 the phenomenon of local skin reactivity has received con- 

 siderable attention of investigators. No definite conchisions, 

 however, can be dra^vn as yet concerning this problem since very 

 few quantitative experiments ha\'e been carried out thtis far. 



In my early ^vork, tryptic digest broth ctiltine filtrates of se\- 

 eral strains of B. typhosus ^vere exposed to 60- and 100° c. for 

 one hoiu' and aiitoclaved at 15 lbs. pressme for forty-five minutes 

 and one hotn\ The materials thtis treated and diluted 1:2 were 

 used for skin preparation. Large doses of luitreated filtrates ^vere 

 injected intravenously (3 c.c. per kilo of body weight) . The 

 results indicated that the skin-preparatory factors of B. typhosus 

 possess considerable heat resistance. Filtrates derived from certain 

 strains lost these factors Avhen autoclaved for forty-five minutes. 

 There was encotuitered, how'ever, a filtrate of one strain which 

 resisted aiuocla\ing at 15 lbs. pressure for one hoin\ Thus, in 

 these earlier qualitati\e experiments there was noticed a differ- 

 ence in heat resistance of skin-preparatory factors deri\ed from 

 various strains of the same microorganism (Shwartzman, 1928^'). 

 The purpose of more recent experiments Avas to make qtiantita- 

 tive studies on the effect of heat upon both skin-preparatory and 

 reacting factors. As wall be described later (p. 181) the potency 

 of the filtrates could be correlated Avith the dination of reactivity 

 induced. The potency of preparations exposed to different tem- 

 peratures Avas then graded by determination of the length of state 

 of reactivity induced and by quantitative titrations of their react- 

 ing potency. These experiments showed distinctly that heating of 

 B. typJwsus "agar washings" filtrates at 60° c. for one hotu- did 

 not shorten the dination of local skin reactivity and did not in- 



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