50 CHAMBERLAIN, VEDDER, AND WILLIAMS. 



in the above experiment was not chemically pure. Consequently 

 we were unable to obtain any information as to the chemical 

 nature of the substances removed from the extract of rice polish- 

 ings by this method. 



Experiment 21. — Therefore, a second experiment was per- 

 formed in the following manner: The extract obtained from 

 10 kilograms of polishings was dialyzed, according to the method 

 described in our previous paper, and the diffusate was then 

 filtered through animal charcoal (Kahlbaum I). The filtrate 

 was clear and colorless. This filtrate was then administered to 

 4 fowls that were being fed on polished rice. Two of these 

 fowls developed neuritis on the twenty-fifth day, 1 on the twenty- 

 eighth, and 1 on the thirty-fifth day. This showed conclusively 

 that the neuritis-preventing substance remained behind in the 

 charcoal, thus confirming the results obtained in our previous 

 experiment. 



The charcoal was then transferred from the filter to a flask 

 and was mixed with 500 cubic centimeters of ether. The mix- 

 ture was allowed to stand in the ice Tdox for two days, being 

 repeatedly shaken during this time. The ether was then filtered 

 off and evaporated, and the ethereal extract so obtained was 

 redissolved in water. Four fowls were fed on highly milled rice 

 and given in addition a daily dose of this extract. One fowl de- 

 veloped neuritis on the twentieth day, 1 on the twenty-third day, 

 1 on the thirty-eighth day, and 1 on the forty-second day. 

 Therefore, it was apparent that the neuritis-preventing prin- 

 ciple was not removed from the charcoal by the ether. 



The charcoal was then treated in a similar manner with 1 

 liter of absolute alcohol. The alcoholic extract obtained was 

 of a yellowish tinge and distinctly acid to litmus. The alcohol 

 was evaporated and the residue redissolved in water as in the 

 case of the ethereal extract. Four fowls were fed on highly 

 milled rice plus a daily dose of this extract removed from the 

 charcoal by alcohol. One fowl developed neuritis on the twenty- 

 third day, 1 on the thirty-second day, 1 on the thirty-seventh, 

 and 1 fowl remained well for sixty-one days. As a result of 

 this experiment it is clear that the neuritis-preventing substance 

 was not removed from the charcoal by absolute alcohol. 



The charcoal was then washed with 3 liters of distilled water, 

 shaking the charcoal up with successive portions of water and 

 permitting the extraction to last for ten days. The water re- 

 covered from the charcoal was also acid to litmus. Four fowls 

 were fed on highly milled rice plus a daily addition of this 



