Heterotrophic bacteria recycle carbon, regulate dissolve organics, and comprise much of the biomass of the oceans. Typical organisms are culture resistant, and a factor of 20 smaller with one-tenth the DNA of commonly studied bacteria. To study these oligotrophic ultramicrobacteria, Dr. Button has developed several new techniques. One is high resolution flow cytometry which gives a rapid accurate analysis of populations in seawater and cultures derived from them, including measurements of population, cell size and DNA content per cell. Another is janusian kinetics which bases nutrient transport rates on molecular composition and allows improved descriptions of the ability of whole cells to collect nutrients. Third is a dilution- culture procedure which greatly expands the number of oligotrophic bacterial species that can be cultured. Representatives of what appear to be typical marine bacteria are now on hand. Preliminary data indicate peculiar sensitivity exhibited as a growth-dependency of individual organisms on the presence of others. Dr. Button will to explore these peculiar population dependencies, bacteria and the distributions of organisms that have them, their nutritional requirements, kinetic characteristics, and ability to attain high population densities, in an effort to understand the dynamics and ecology of marine microorganisms in the context of kinetic control of dissolved organics.