Such marked _increases_ from soil inoculation cannot of course be expected in cases where the soil has previously borne leguminous crops of similar nature and therefore already contains the root bacteria. Hence Duggar found no increase of production when inoculating for cowpea, land that had borne that crop two years before and already contained the root bacteria. In the arid region, where the almost universally calcareous soils usually bear a natural growth largely composed of various leguminous plants, inoculation is likely to be less commonly effective than in the humid region east of the Mississippi, where leguminous plants are much less generally present in the native flora. The distinctive agricultural function of supplying nitrogen to the soils on which they grow, renders inexcusable the persistence of some writers and teachers in designating all forage plants as “grasses.” Whatever excuse there may have been for this practice so long as the nitrogen-gathering function of the legumes was unknown, disappears with this discovery, and the misleading misnomer should be banished from agricultural publications and lectures, at the very least. _Other Nitrogen-Absorbing Bacteria._—An increase in the nitrogen-content of some soils, aside from the action of leguminous root-bacteria, has long been observed. As already stated, this increase was at first ascribed to certain green algæ often seen to develop on the soil surface; but it has now been shown that the nitrogen-gathering function belongs to at least two bacteria, one of which (_Clostridium pastorianum_) was discovered by Winogradski, the other (_Azotobacter chroococcum_) by Beyerinck, and has since been farther investigated by Koch, Kröber, Gerlach and Vogel, and last by Lipman and Hugo Fischer. According to the latter it seems likely that Azotobacter chroococcum lives in symbiosis with the green algæ, all of which, like the Azotobacter itself, develop with special luxuriance on calcareous soils. Lipman (Rep. Agr. Exp’t Station, New Jersey, 1903 and 1904) describes as _Azotobacter vinelandii_ a form somewhat different from the A. chroococcum, the nitrogen-assimilating power of which he tested quite elaborately. He exposed to air pure cultures of _A. vinelandii_ in nutritive solution containing the proper mineral ingredients, and glucose 20 grams per liter. 100 cub. centimeters of this solution was exposed in flasks of respectively 250, 500 and 1000 cc. content, therefore having greater surface in the larger flasks. After ten days, the amounts of nitrogen fixed were found to be respectively 1.67, 3.19 and 7.90 milligrams. When mannite solution was employed instead of glucose, a similar fixation was observed; and it was also shown that the presence of combined nitrogen in the forms of nitrates or ammonium salts discouraged the fixation by the bacillus.