254 



Scientific Proceedings (115). 



same time put under ether anesthesia which was continued for 

 two hours. The pigs in the first series died in eighteen hours while 

 those in the second series survived. 



Further experiments are being carried out which attempt to 

 gain an insight into the nature of the phenomenon, how far it 

 can be applied with relation to other toxins and the effect of 

 other anesthetics. The quantitative and time relationships are 

 also being studied. 



130 (1712) 



The composite nature of botulinus toxin. 



By J. BRONFENBRENNER and M. J. SCHLESINGER. 



[From the Department of Preventive Medicine and Hygiene, Harvard 

 Medical School, Boston.] 



As we will show in detail in another paper, the lethal dose 

 of botulinus toxin by the mouth is roughly 1,000 removed from 

 that sufficient to kill by the intraperitoneal route. This rela- 

 tion seems to hold true for all the laboratory animals which we 

 investigated, including birds, and is responsible for the failure 

 of certain investigators to kill birds by feeding even large quantities 

 of weak toxin. 



In attempting to purify the toxin by precipitation, we were 

 surprised to find that, whereas the purified toxin retained its 

 full potency when tested by injection, it became 100 times less 

 toxic by mouth. In general the further the purification was 

 carried, the greater was the loss in potency of purified toxin when 

 tested by mouth. We have been able to reestablish the toxicity 

 (by mouth) of such purified toxin by merely adding to it the 

 substances removed by the process of purification. 



Since the potency of our purified botulinus toxin as tested by 

 injection remains the same, whereas the toxicity by mouth varies 

 according to the degree of purification of the toxin, it seems to 

 us that the power of crude botulinus toxin to be absorbed through 

 the intestine is dependent upon the presence of secondary sub- 

 stances mixed with the true botulinus toxin. 



