Der zönoblast als besondere Organisationsstufe der coccalen Grünalgen (chlorophyta)

Abstract

Summary The multinuclear state in the microscopic coccoid green algae is a parallel to the siphonous state. Such “cells” which are in the main phase of development multinuclear are strictly not identical with the classic concept of a cell (algal cell) and do also not agree with the concept of a true coccoid habit. The coenoblast (coenocyt) presents a separate type of a habit and occurs not only in different classes of the green algae but also in the Chrysophyceae and Xanthophyceae. It is known that some uninucleate species of the Chlorococcales as well as of the Chlorellales are during sporogenesis for a very short time multinuclear as the mitoses precede the plasmatomy. But they remain in vegetative, trophic stage uninuclear before the reproduction is starting. The coenoblastic Chlorococcales and Chlorellales on the contrary are multinuclear during the whole vegetative phase (polyenergide during the trophic growth period) and the mitoses are progressive. Only the reproductive cells and the germlings are uninucleate. The characters of a coenoblast are given. The taxonomic value is that of an order or family as the mentioned state does not represent a natural group. On the contrary the usually given value of a genus would discredit the polyenergid habit.