“…This evidently holds good for the effect of the hay plants investigated, even in virgin soils. As to the sporeformers, it is reported that they do not multiply extensively in the rhizosphere (Krassilnikov, Kriss, and Litvinov, 1936, Starkey, 1938, Clark, 1939, Lochhead, 1940. The present investigation showed that this group is promoted under certain conditions, and by certain plants, but that the degree of the »rhizosphere effect* upon these bacteria in general is distinctly weaker than on the non-sporogenous bacteria.…”