ETIOLOGY OF BERIBERI. 49 



excludes cholin and lecithin from further consideration as the 

 neuritis-preventing substance of rice polishings. 



While our observations had led us to believe that the neuritis- 

 preventing principle in rice polishings was insoluble in ether, 

 there was no conclusive evidence with regard to this point. To 

 settle the matter, polishings were extracted with ether as follows: 



Two kiloprrams of polishings were mixed with 6 liters of ether and, after 

 macerating for twenty-four houi-s, the ether extract was filtered off. The 

 extraction was repeated with fresh ether for a second twenty-four hours, 

 the filtrates combined, and the ether evaporated by the current from an 

 electric fan. Three hundred cubic centimeters of residue, consisting chiefly 

 of fat, were obtained from 2 kilograms of polishings. 



Experiment 19. — Four fowls were fed on polished rice plus a 

 daily addition of 2 cubic centimeters of the ethereal extract of 

 rice polishings. One fowl developed neuritis in twenty-one 

 days, 1 in twenty-nine days, and 1 in thirty days. From this 

 experiment we concluded that the neuritis-preventing principle 

 is insoluble in ether. 



We have never seen oedema in any of the fowls that have 

 developed polyneuritis, although this symptom has been noted 

 by several other observers, including Shiga (9). The influence 

 of a salt-free diet in reducing the oedema of nephritis has been 

 much emphasized of late. Since the fowls fed on highly milled 

 rice receive practically no salt, it seemed possible that the addition 

 of a considerable quantity of sodium ahloride to the food might 

 produce this symptom. In order to test this hypothesis Ex- 

 periment 20 was performed. 



Experiment 20. — Four fowls were fed on polished rice, and in 

 addition were given a daily dose of 1 gram of sodium chloride 

 diluted in 10 cubic centimeters of distilled water. This would 

 be equivalent to a dose of 50 grams daily for a man. The 4 

 fowls developed neuritis on the twenty-third, twenty-sixth, 

 twenty-seventh, and thirty-third days, respectively, but at no 

 time did they show any signs of oedema. Therefore, we con- 

 cluded that the presence or absence of sodium chloride is of no 

 importance with regard to the development of oedema in poly- 

 neuritis gallinarum and probably in beriberi. 



In a previous paper (2) we reported an experiment demon- 

 strating that the neuritis-preventing principle was adsorbed 

 when the extract of rice polishings was passed through an animal 

 charcoal filter, and that a portion of the neuritis-preventing 

 element was recovered when the bone black from the filter was 

 washed with distilled water. Unfortunately, the charcoal used 



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