STUDIES ON PIGMENTED MICROORGANISMS FROM APHOTIC MARINE ENVIRONMENTS1

Abstract

An attempt has been made using electron microscopy to identify those organisms which make up an abundant and ubiquitous flora in the aphotic region of the North Atlantic Ocean. Only low resolution micrographs were obtained, but these showed that in the 375–450‐m depth range sampled there were three distinct groups of microorganisms. The first group was composed of cells of extremely low level of organization, not more complex than that found in procaryotes. The second group, present in lower concentrations, was clearly eucaryotic and possessed chloroplasts. The final group comprises a melange of cells observed too infrequently to warrant individual consideration. It is suggested that all three groups, which are essentially indistinguishable in the light microscope, correspond to the organisms referred to as olive‐green cells by Hentschel from the 1925–1927 Meteor expedition.