Abstract
The paper describes the forward streaming, growth, and division of the vegetative cell of Basidiobolus ranarum. The cell is several hundred microns long and has a single large nucleus. Mitosis is invariably followed by cell division. Both processes have been studied in the living cell by ordinary and phase contrast microscopy. Mitosis is accompanied by a temporary coarsening of the organisation of the cytoplasm and a considerable slowing down of the rate of growth of the cell wall tube. Fixed and stained preparations have shown that there is a large number of small chromosomes and that the mitotic spindle is formed from the nucleolus. Basidiobolus appears suitable for observations on the cell duplication cycle and the physiology of mitosis.