ETIOLOGY OP BERIBERI. 419 



It has been known for a long time that the efficacy of an 

 extract of rice polishings is destroyed by heating at 120 ' C. or 

 even by prolonged boiling. It has been generally assumed that 

 the neuritis-preventing principle was destroyed by this heat, 

 but there remained the distinct possibility that this substance 

 might be volatile and thus be lost although not actually destroyed. 



Experiment 2Jt. — In order to test this possibility, a quantity 

 of extract of rice polishings, prepared as described in previous 

 papers, was tested on fowls and found to prevent polyneuritis. 

 The extract was then placed in a flask and distilled, the process 

 being continued until practically the entire quantity of extract 

 had been obtained in the distillate and nothing remained in the 

 flask but a thick syrupy mass. The distillate and the residue 

 were each diluted with distilled water until 1 cubic centimeter 

 was equivalent to 1 gram of polishings. 



Four fowls were fed on polished rice with a daily addition of 

 10 cubic centimeters of the distillate from the extract of rice 

 polishings. 



All 4 fowls developed neuritis in twenty-three, twenty-four, 

 twenty-eight, and twenty-nine days respectively. 



Four fowls were fed on polished rice with a daily addition of 

 10 cubic centimeters of the residue remaining after distillation. 



All 4 fowls developed neuritis in nineteen, twenty-three, 

 twenty-six, and twenty-nine days respectively. Therefore, it 

 appears that the neuritis-preventing principle is not volatile, 

 but is actually destroyed by heat. 



The possibility that this substance was an alkaloid was next 

 considered. Its powerful action and the minute quantities in 

 which it is present in the rice polishings suggest this possibility, 

 but an ethereal extract of rice polishings had already been shown 

 to be ineffective. However, the previous ether extract was 

 slightly acid in reaction and some alkaloids can not be extracted 

 in an acid solution. 



Experiment 25. — A portion of extract of rice polishings was 

 rendered very slightly alkaline with sodium hydroxide and was 

 then extracted by shaking with successive portions of ether. 

 The ether was then evaporated by means of an electric fan and 

 the residue so obtained was rendered slightly acid with hydro- 

 chloric acid and diluted with distilled water to the original bulk 

 of the extract. The extract remaining after treatment with 

 ether was then extracted with chloroform, by shaking with 

 successive portions of chlorofonn until nothing further could 

 be extracted. This chloroform was then evaporated off by means 



