398 CHAMBERLAIN AND VEDDER. 



our observation. They also stated their inability to obtain the diffusate 

 resulting from the process of dialysis owing to its putrefaction. There- 

 fore, it will be interesting to give in detail the method by which we 

 succeeded. 



The condensed extract was placed in a parchment bag and suspended in a 

 glass jar containing distilled water in such a manner that the surfaces of the 

 two liquids were on the same level. A few cubic centimeters of chloroform, 

 were then added to the bag and also to the water outside the bag, and the 

 whole apparatus was placed in the ice box. Tlie combined action of the cold 

 and the chloroform prevented all decomposition and the dialysate and diffusate 

 were perfectly sweet after ten days of dialysis. Tlie diffusate was removed 

 every two days, and replaced by fresh distilled water, in order that the dialyzable 

 substances might be completely removed from the extract in the bag. These 

 separate portions of the diffusate were subsequently mixed before feeding it 

 to fowls. This method was effectual and enabled us to collect and test the 

 diffusate, proving that it contains the neuritis-preventing principle. 



The next ^tep was to consider the action of the sucrose contained in 

 this extract. It was utterly inconceivable on physiologic grounds that 

 sucrose could have the slightest power to prevent neuritis, but since 0.88 

 out of 1.34 per cent of the total solids consisted of this dialyzable sub- 

 stance, we decided to give it a fair trial by experiment. Two separate 

 experiments were undertaken for this purpose as follows: 



Experimeni 5.^ — A quantity of extract was prepared from rice polish- 

 ings as described previously, and was then inoculated with kitchen yeast 

 and allowed to undergo fermentation in the incubator. Fermentation 

 was very rapid for several days but finally ceased entirely. The extract 

 was then filtered until it was absolutely clear and the microscope showed 

 no yeast cells in the filtrate, in order to avoid adding yeast cells or their 

 subsequent decomposition products to the extract. The alcohol formed 

 by fermentation was then expelled by boiling the filtrate. This was 

 subsequently diluted to its original bulk, reinoculated with yeast, and 

 fermented again in order to make sure that the accumulation of alcohol 

 had not stopped fermentation before all the sugar was exhausted. After 

 assuring ourselves that the sugar was all removed from the extract by 

 fermentation, the yeast cells were again carefully filtered out. 



This extract contained all the substances extracted from rice polish- 

 ings by this method with the exception of the sucrose,* and it was made 

 in such proportion that 10 cubic centimeters of the extract would contain 

 the substances extr,acted from 10 grams of polishings. A solution was 



^ Experiments one, two, three and four are detailed in our former article the 

 title of which is given in reference one. 



* The sucrose was undoubtedly removed. It is possible that some other sub- 

 stances also may have been broken up by the action of the yeasts or associated 

 bacteria. We have some reason to think that the neuritis-preventing substance 

 may be decomposed by action of bacteria. 



