86 THE SOIL SOLUTION 



salts was boiled vigorously to eliminate the alcohol and water 

 was then added to restore the original concentration. A third 

 solution was prepared by bringing together the organic and in- 

 organic substances which had previously been separated as above 

 described/ The three solutions were used as water cultures for 

 wheat seedlings, a solution of the original manure extract being 

 taken for a check culture. The original manure extract and the 

 reconstructed manure extract gave plants of about equal de- 

 velopment. The culture containing the organic dissolved sub- 

 stances only, gave plants of nearly, but not quite, equal de- 

 velopment to those grown in the check culture. But the plants 

 grown in the solution containing the dissolved minerals only, 

 while fine plants and making what would ordinarily be considered 

 a good development, were decidedly smaller as regards their 

 aerial parts, and the roots were in no wise comparable to the 

 roots of the plants grown in the cultures containing the dissolved 

 organic substances. 



This last experiment has been repeated, with dissolved sub- 

 stances prepared from another manure extract, but in this case 

 the organic and inorganic substances were separated by dialysis. 

 This suggested yet another experiment, in which it was sought 

 to hasten the process of dialysis, by introducing electrodes into 

 the manure extract, each electrode being surrounded by some 

 porous membrane, either of parchment paper, or unglazed por- 

 celain. Not only were the mineral constituents of the manure 

 extract readily separated in this way, passing into the electrode 

 chambers, as did also to some slight extent organic compounds, 

 but also about the outer walls of the electrode chambers there 

 was marked segregation and deposition of organic materials. 

 The organic substances deposited at the cathode were found to 

 stimulate greatly the growth of wheat seedlings while those de- 

 posited at the anode were found to retard the growth of seed- 

 lings. It seems probable, therefore, that stable manure con- 

 tains organic components which produce as great or greater 

 effects upon growing plants as do the inorganic substances it 

 contains : that on the whole these organic components induce 



