[Septum formation and cytomorphogenesis in Micrasterias denticulata after the action of ethanol].

Cells of Micrasterias denticulata were treated with ethanol during the stage of septum formation. After this, cells were transferred into nutrient solutions and here the further development was studied. The following effects were observed: 1. A one-hour treatment of the cells with 10% ethanol lead to an irreversible inhibition of the septum growth. Because cell-elongation (bulbus-formation) remained uneffected, binuclear "double-cells" with a teratogenic "middle section" were formed. 2. The degree of differentiation of this "middle section" depends on the extent of septum formation. Thus a direct relationship between the degree of differentiation of the "middle section" and septum formation exists. 3. The experiments seem to indicate that the septum carries the prospective pattern of differentiation in a template-like manner. This fact is in good agreement with the hypothesis on a "septum-initial-pattern" in Micrasterias which we recently advanced. 4. It could be observed that in most cases the teratogenic "middle section" forms additional 3-dimensional lobes. A remarkable relationship exists between the differentiation of these lobes and the degree of lobe formation of the "middle section".