Page:Popular Science Monthly Volume 63.djvu/339

Rh Be it known that we, Friedrich Nobbe and Lorenz Hiltner of Tharand, pared for transport in fluid cultures. The colonies in the agar-gelatin are dis-inoculation of soil for the cultivation of leguminous plants and we do hereby declare the following to be a clear and exact description of the invention:

Since the function of the root nodules or tubercles of the Leguminosæ in the supply of nitrogen to these plants has been discovered by the fundamental researches of Hellriegel we have been working on this problem for a number of years, and have examined more especially the bacteria in said nodules or tubercles (first identified and isolated in cultures by Beyerinck) in order to determine the relationship between the bacteria and the reception of the free uncombined nitrogen of the air in the soil by the various kinds of Leguminosæ. These researches have resulted, in the first place, in the confirmation of the at that time still disputed fact that the introduction of these bacteria into the soil produces, without exception, in soil free from these bacteria, the root nodules or tubercles on the plants in question having papilionaceous flowers and enables these plants to assimilate the free nitrogen. A soil inoculated with these bacteria, even when it contains absolutely no nitrogen in an assimilable form so that the plants without any such inoculation would starve, enables the Leguminosa? to produce as rich a yield of dry material and nitrogen as they would otherwise produce if grown in a richly manured soil containing much assimilable nitrogen.

It has been established by us as an entirely new fact that the tubercle bacteria of the various Papilionacea? are of full strength (i. e., in the production of efficient nodules or tubercles) only in that species (of leguminous plant) from whose root tubercles they weie themselves obtained. With closely allied species they are of less strength and with systematically different species they are useless or inactive. Bacteria cultures from pea roots, for example, are quite useless for Robinia plants, while they promote the growth of peas in a very energetic manner, and that of the allied vetches somewhat more feebly; on the other hand, the bacteria from Robinia nodules or tubercles are quite efficient with Robinia plants, but in a lesser degree with Colutea, and are absolutely useless with peas.

At first sight it might possibly be thought that the production, transport, and distribution of such large masses of crude inoculating material as would appear to be necessary for the sufficient impregnation or treatment of large areas of land would be very difficult and costly, and therefore not practicable, while there would also be the danger that in the crude inoculating material, besides the active bacteria of the root nodules or tubercles, there would be carried from field to field, at the same time, microscopic organisms which would be detrimental to growth and would interfere more or less with the action of the inoculating material. Our process is, however, free from any such objections as those above mentioned, inasmuch as bacteria bred in quantities directly from the nodules or tubercles of the Leguminosæ in pure cultures are used as the inoculating material. Farmers are, therefore, placed in a position to make land, which was unfruitful by reason of its lack of nitrogen, fit for the cultivation of fodder and other plants belonging to the order of the Leguminosæ and to insure and increase the yield of soil. This inoculation has, moreover, an essential practical bearing in connection with the so-called 'green manuring'

Our process of inoculating land with tubercle bacteria is to be carried out as follows: The active bacteria to promote the growth of the Leguminosæ are delivered to the farmer in glass tubes or other suitable packages, which contain pure colonies thereof in agar-gelatin having suitable additions for propagating such bacteria, for instance sugar, asparagin and an aqueous extract of the green