OBSERVATIONS OF THE FINE STRUCTURE AND MODES OF GROWTH OF A STREPTOMYCETE

Abstract

A study of ultrathin sections of an osmium fixed and methacrylate embedded streptomycete revealed its possession of some morphological characters found in the eubacteria and others found in the fungi. In the log-phase, the cells have a typically bacterial nucleus which contains dense strands of material, which exhibts no limiting membrane and which appears to divide amitotically. The cytoplasm frequently contains aggregates of membranes which may be arranged in parallel pairs or at random. Sometimes, an additional membrane appears within the plasma membrane. In the stable-phase, the cells possess a homogeneous nucleus resembling that of fungi. This nucleus also lacks a limiting membrane. Cellular division occurs by both a eubacterial type of centripetal deposition of cell wall material and by a fungal type of branching. The branches may subsequently develop transverse cell walls.