62 LOCAL TISSUE REACTIVITY 



flucnce the reacting potciuA. Ilic exposure to loo c. lor twenty 

 ininiites shortened the (huation ol reactivity from seventy-two to 

 t\venty-foiir horns and reduced the reacting titer from 550 to 

 250 units per c.c. Thus, possibly loecause of a finer method of 

 titration employed in these experiments, there was noted a par- 

 tial but substantial reduction in the skin-preparatory and react- 

 ing potencies at a temperature as lo^v as 100^' c. 



The other reason for the discrejiancy Ijetween the early and 

 present exj^eriments coidd ha\e l)een due to the fact that "agar 

 ^vashings" filtrates, instead of tryptic digest broth ctdtine filtrates, 

 Avere used in the latter experiments. Inasmuch as the tryptic di- 

 gest broth cidtine filtrates contain more autolytic material than 

 the "agar washings" prej^arations, it seems of interest to investigate 

 further whether the active principles oljtained through cell dis- 

 integration {i.e., endotoxic j^reparations) differ from soluble exo- 

 toxic materials in heat lability (Shwartzman, 1932^) . 



In experiments of Schneierson, in my laboratories, the reacting 

 potency of B. dyseiiteriae Shiga "agar washings" filtrates and B. 

 dyseiiteriae Shiga exotoxin prepared in egg medium by the 

 method of Olitsky and Kligler (1920) , was reduced from 40 to 5 

 tuiits per c.c. and 50 to 5 tniits per c.c, respectively, after heating 

 at 80^ c. for one hour. In contrast, Shiga bacillus endotoxin also 

 prepared by the method of Olitsky and Kligler remained unal- 

 tered after exposure to the same temperature. 



Burnet (1931) fotnid that boiling of cultmes autolyzed accord- 

 ing to Besredka's method for five minutes, had no effect on their 

 skin-preparatory activity. 



It appears from Uyeda's (1934) experiments that the skin- 

 preparatcjry factors of "agar \vashings" filtrates of J'ihrio cholerae 

 resist exposure to 90° c. No titrations were made in order to de- 

 termine whether there Avas a partial reduction of the potency of 

 the filtrates. 



According to Stolyh^vo (1935) , the phenomenon-producing and 

 lethal potencies of filtrates of typhoid and paratyphoid cultin^es 

 are not destroyed by boiling for thirty minutes. Heating of the 

 filtrates in the autoclave under ii/^ atmospheric pressure in\ari- 

 ably inactivates the preparations. 



In Boquet's experiments (1935) the active jjrinciples of B. 

 lepisepticus Avere not inactivated by heating of filtrates at 100° c 

 for ten minutes. 



Pabst and Branham (1933) suggest that 37° c. may inactivate 



