[Turning points in cytology].

There is given a concise and woodcut-like survey over the history of cytology with was born by the pioneering of Hooke, Grew, Malpighi, and van Leeuwenhoek at the end of XVIIth century and three crises of this science. The first crisis of cytology resulted from barren discussions of the so-called preformation hypothesis and the monadism of Leibniz. These philosophical speculations caused a melting away of the concrete facts during the XVIIth century. After the rebuilding of cytology by Meyen and Brown during the XIXth century's early thirties and the propounding of the early cell-theory by Schleiden and Schwann, the second crisis was provoked since Schleiden and Schwann, clearer than Meyen, kept the hypothesis of equivocal or spontaneous generation that was alive since Aristotéles. This 2nd crisis showed a belated sequel in the middle of XXth century brought about by sloppy investigations of Lepesinskaja. The third crisis concerns the question whether there is or whether there is not existent a membran enveloping every animal cell. Whereas Schwann himself presupposed the cell membran as an integral part of each cell, Max Schultze negates its existence. After the creation of the membran theory of synapse by Sherrington, the neuron theory by Ramón y Cajal, and the membran theory of narcosis by Meyer and Overton, the negation of the cell membran was being combined successively with the neovitalistic hypothesis of neuronal networks of Bethe and others. This spectre could really wiped out not before the modern histochemistry and electron microscopy were established in the fifties of our century.