Page:Popular Science Monthly Volume 63.djvu/343

(Melilotus alba) were grown upon corn extract with agar. Again considerable difficulty was encountered because of lack of information regarding the behavior of this particular variety or species of rhizobium in artificial culture media. It was not until the early part of July that definite and satisfactory conclusions were reached regarding the identity of this organism in the culture media indicated. The rhizobia were now transferred to fresh corn extract media from time to time for about six weeks; in order to effect the desired adaptive changes in the microbes. Some preliminary field experiments were carried on at a farm near Fairbury, Illinois. Plots of stubble ground were selected in which oats had been grown during the season. The ground was ploughed and harrowed repeatedly. Each plot of ground was duplicated for control purposes. On August 10 the plots were planted with white dent corn mixed with the rhizobia cultures and a small quantity of water. The seeds germinated uniformly with no appreciable differences in the various plots. Subsequent growth was carefully observed for a period of four weeks. No very marked difference was noticeable. The corn treated with rhizobia grown in neutral corn-extract agar seemed to thrive somewhat better than the rest, but the difference was not sufficiently marked to be noteworthy. The corn treated with acid agar corn-extract rhizobia showed no apparent improvement over the normal or untreated corn. The same could be said of the corn treated with crushed nodules of sweet clover. Opportunity did not present itself for making a comparative microscopic examination of the roots of the corn of the various plots. Oats was also experimented upon, but with no marked results. This in brief is the outline of the experiments of 1903 and, although no satisfactory results were obtained, the preponderance of experimental evidences again seemed to point to ultimate success. In fact so sanguine had the writer become of early marked success that he made application for letters patent for the process, but the application in the form in which it was presented was rejected on the patents by Nobbe and Hiltner and by Hartleb. The specifications filed September 29, 1903, read in part as follows:

The invention relates to the process of fertilizing the soil and increasing the yield of crops by means of specially modified pure cultures of the microbes or organisms found in the soil and in the root nodules or tubercles of plants belonging to the leguminosæ or bean family, and has for its object to render the process more effective, much cheaper and practically without the expenditure of additional labor. The living microbic fertilizer, consisting of the above mentioned modified organisms is applied by simply mixing a small quantity of the culture with the seeds just prior to planting, and introducing it into the soil simultaneously with the seed. With the germination of the seed thus treated, the modified microbes will also begin to multiply and appropriate for the use of the plant, the free nitrogen of the air.