[Morphological changes in chloroplasts and mitochondria of darkened Acetabularia cells]

Cell differentiation is not realized in darkened Acetabularia cells, although the "potentials" concerned are present. In contrast to cell differentiation, young chloroplasts and mitochondria of nucleated as well as of enucleated cells are able for the differentiation of characteristic structural components under dark conditions. This behaviour indicates that these cell organelles possess own differentiation mechanisms. In analogy to cell differentiation which is based on actions of nuclear DNA, the differentiation processes within the organelles are proposed to be dependent on actions of their own DNA.