In the symbiosis of leguminous plants and nitrogen-gathering bacteria we have a partnership or relationship of immeasurable value to agriculture. Here is a class of plants (legumes) that are capable of consuming or utilizing nitrogen in quantities larger than could possibly be obtained from ordinary soils for any considerable length of time. They have no power in themselves of taking nitrogen from the atmosphere, and to them the symbiotic relation with this low order of plants (the nitrogen-gathering bacteria) is especially helpful, and for the best results it is absolutely necessary. [5] There are some noteworthy exceptions to this rule (see following pages for illustration), and there is some evidence that, by a comparatively long process of breeding, or evolution, the bacteria which naturally live upon one kind of legume may gradually develop the power to live upon a distinctly different legume to which they were not at first adapted. Of course this process of forcing bacteria to live upon a legume to which they are not naturally adapted has little or no practical value because it is unnecessary if there is a species of bacteria which naturally lives upon the same legume. On the other hand, if, by any such process of breeding, or evolution, a species of nitrogen-gathering bacteria could be developed which could live on a non-leguminous plant, as corn, for example, it would be of incalculable practical value. As yet the efforts of bacteriologists, working on this problem, have given only negative results, so far as known to the writer. [6] In this connection attention is called to the fact that the so-called “spot disease” of alfalfa, which is not uncommon in the western states, especially during wet seasons, became somewhat prevalent in Illinois in 1903. When the effect of this disease becomes marked, the leaves turn yellow and growth is retarded. If this occurs the alfalfa should be clipped. This is the only effective remedy known to be practicable. Seeding alfalfa with a light nurse crop is gaining favor in Illinois. [7] Some of these observations have already been reported in the agricultural press. (See, for example, the Breeders’ Gazette, September 9, 1903, page 391, and September 16, 1903, page 442.) [8] Steamed bone meal is the most economical and satisfactory form of phosphorus for use on Illinois soils, unless ground rock phosphate (not acid phosphate) shall prove to be still more economical. Experiments to determine this are in progress. [9] Just how long the bacteria will live in a soil without a leguminous crop upon which they can feed is not definitely known. Certainly they live for two or three years, but probably not more than five or six years. Further investigation is needed to establish the length of time the different kinds of bacteria may remain in the soil under different conditions.