Numbers of Bacteria and Actinomycetes in a Kenya Soil

Summary The estimates of numbers of bacteria and actinomycetes derived from plate counts made from soil samples taken at Muguga, Kenya, varied with the extent to which the soil was diluted. Low dilutions gave small, and high dilutions large, estimates. The ratio between direct counts and plate counts on the same sample was wide at first, but became narrow as the drought of early 1953 was prolonged. The percentage of actinomycete colonies on plates was less than 30 at first but rose to over 90 when the drought was well established. It is concluded that the drought‐resistant part of the microflora in this surface soil is almost entirely composed of actinomycete spores.