ETIOLOGY OF BERIBERI. 45 



to protect a fowl from polyneuritis could not contain more than 

 these quantities of amido substances. 



It will be seen that all of the experiments were nej?ative, and 

 showed that none of these substances possessed any protective 

 power. Although these experiments do not exclude all such sub- 

 stances which are present in the extract of rice polishing-s, it 

 seems improbable that the remaining ones can be of importance. 



An objection may be raised to part of these experiments be- 

 cause of the fact that the extract was treated with alkaline 

 reagents. Fraser and Stanton (7) have shown that treatment 

 with sodium hydrate destroys the neuritis-preventing substance. 

 We have repeated this experiment and have found that treat- 

 ment of the extract with sodium hydrate does remove its pro- 

 tective action. However, it should be remembered that the 

 chemical procedure which we followed, as described above, is 

 the recognized method for the isolation of the histon bases ; there- 

 fore, whatever effect the alkaline reagents may have had on the 

 neuritis-preventing substance, they could not have affected such 

 substances as arginin or histidin. That the neuritis-preventing 

 substance may be destroyed by such treatment is simply another 

 argument against the possibility that any protective action is 

 possessed by the compounds in question. 



Since the extract used in the above experiments was a dif- 

 ferent lot from that employed in the work previously reported 

 by us(i) (2), a control experiment was performed in order to 

 be certain that the extract would prevent neuritis before it 

 was put through the chemical processes already described. For 

 this purpose the concentrated extract was diluted in such pro- 

 portion that 1 cubic centimeter represented the substances 

 dissolved from 1 gram of rice polishings. Four fowls were then 

 fed on polished rice with a daily dose of 10 cubic centimeters of 

 this diluted extract. These fowls all remained well for fifty 

 days, when they were released. This definitely shows that the 

 neuritis-preventing substance was present in the extract previous 

 to its chemical treatment. 



We now considered that it might be of interest to determine 

 exactly what dose of this extract was required in order to pre- 

 vent neuritis and for this purpose performed Experiment 16. 



Experime7it 16. — Four fowls were fed on polished rice plus 

 a daily dose of 5 cubic centimeters of the extract of rice polish- 

 ings. These 4 fowls also remained well for fifty days when 

 they were released. Four fowls were then fed on polished rice 

 plus a daily dose of 2.5 cubic centimeters of the extract of rice 



