ETIOLOGY OF BERIBERI. 51 



watery extract from the charcoal. One fowl developed neuritis 

 in twenty-three days, 1 in twenty-six days, 1 in thirty-six days, 

 and 1 remained well at the end of forty-eight days. Therefore, 

 it appeared that the neuritis-preventing principle was not re- 

 moved, by extraction with water, from the pure charcoal used 

 in this experiment. 



The charcoal was next suspended in 500 cubic centimeters of 

 distilled water, and 2 cubic centimeters of this mixture fed daily 

 to 4 fowls subsisting on higly milled rice. Since the charcoal 

 rapidly sinks to the bottom, the flask was shaken just before 

 giving the mixture. The water was used simply as a vehicle for 

 the administration of the charcoal. These 4 fowls all remained 

 well at the end of sixty days. Therefore, we concluded that 

 the neuritis-preventing principle was still retained by the char- 

 coal in spite of the repeated extractions to which it had been 

 subjected. This experiment difi'ered from the one reported 

 previously in that water completely failed to remove the neuritis- 

 preventing principle, while in the former experiment (Number 

 6) this principle seemed to be in part removed, and the watery 

 extract conferred partial protection. We attribute this differ- 

 ence in results only to the fact that in the first instance we used 

 an impure charcoal, while the second time we used a pure 

 product which apparently possessed a greater adsorptive power 

 for the unknown neuritis-preventing substance. 



Experiment 21 fully confirms our former observation that the 

 neuritis-preventing principle in rice polishings is adsorbed by 

 animal charcoal and this knowledge perhaps will be the basis 

 for a method of isolating the substance in comparative purity, 

 provided a means can be discovered for extracting it from the 

 charcoal. 



CONCLUSIONS. 



1. These experiments all substantiate the theory that poly- 

 neuritis gallinarum and beriberi are caused by the deficiency of 

 some as yet unknown substance in the food. We have shown 

 previously that this substance is not phosphorus. 



2. Kohlbrugge's theory that beriberi is caused by an acid intox- 

 ication, which is due to the fermentation of rice by various 

 saprophytic bacteria contained in the kernel, must be regarded 

 as untenable. 



3. To the list of substances which we have shown in previous 

 papers to be of no importance in preventing neuritis of fowls 

 there may now be added the following : Nitrogenous compounds 



