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This experiment was designed to evaluate the importance of inoculation of soybeans when grown on land where well‐nodulated soybeans had been grown previously. The effect of soil conditions, and of time interval following previous inoculation, upon response of soybeans to inoculation was observed. Neither soil treatment or interval of time since the host plant had been grown had any influence upon crop response to inoculation. Even on plots which had not grown soybeans since 1939, inoculation did not increase soybean yields. Although inoculated soybeans gave smaller yields than did the uninoculated in many cases, no significance was attached to this observation. Fields having a total nitrogen content of less than 3,000 pounds per acre gave a higher proportion of gains to losses than those containing more than this amount. Yields of both inoculated and uninoculated crops were greater on soils which had been treated with limestone, phosphate, and potash than on untreated check plots. It is concluded that inoculation should be practiced as an inexpensive insurance policy.

A few species of legume nodule bacteria have been studied by means of the electron microscope in an attempt to discover distinct morphological differences within the genus (Appleman, Barnes, and Sears, 1942). It is the purpose of this paper to present a more detailed study of the morphology of the soybean and sweet clover nodule bacteria, particularly with reference to localized fat areas and nuclear contents, in which classical cytological reagents and specific chemical solvents were used.In order to show differences in cell structure under the electron microscope it is often necessary to alter the density of the cellular components so that a specific region is rendered more or less opaque than the surrounding area. For this

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