SCIENTIFIC PROCEEDINGS. 



One hundred seventeenth meeting. 



Abstracts of Communications. 



Cornell University Medical College, October iq, IQ2I. 

 President Wallace in the chair. 



I (1748) 



Further studies on the nature of botulinus toxin. 



By J. BRONFENBRENNER and M. J. SCHLESINGER. 



[From the Department of Preventive Medicine and Hygiene, Harvard 

 Medical School, Boston, Mass.] 



In trying to duplicate in vitro the conditions as they exist 

 when botulinus toxin is taken by the mouth, we have observed 

 that the acidity equal to that of the stomach contents not only 

 leaves the toxicity of botulinus toxin undiminished, but would 

 actually increase its potency. It has been repeatedly stated in 

 the literature that botulinus toxin resists action of acids, but so 

 far as we know nobody has observed the increase in potency of 

 this toxin resulting from the change in its hydrogen ion con- 

 centration. 



In attempting to establish the extent of this increase in potency 

 we found that under the suitable conditions of the experiment the 

 botulinus toxin which ordinarily kills mice in amounts not smaller 

 than 3 X io~ 7 cc. can be increased in potency to such an extent 

 that 3 X io~ 21 cc. occasionally and 3 X io~ 18 cc. quite regularly 

 kills mice of 18-20 grams in less than 48 hours after the intra- 

 peritoneal injection. While the total solids of such a minute dose 

 of toxin amount to only 3 X io~ 23 grams (this amount including 

 also the inorganic portion of the medium) the toxic product thus 

 obtained, nevertheless, possesses all the essential characteristics 

 of bacterial toxins: it is thermolabile, it acts only after an incuba- 

 tion period, it reproduces in experimental animals typical symp- 



