Regarding the different stainability when using the Luxol fast blue method, two kinds of Purkinje cells of the rat are described: Luxol-positive and Luxol-negative cells. Since, by this method, phospholipids are demonstrated, the author suggests the prospective varying functional condition of these cells. Different tinction of Purkinje cells has been confirmed also by other methods (gallocyanin-chromalaun, thionine, toluidine blue, lithium-haematoxylin, chromalaun-haematoxylin-phloxine and acid phosphatase) in both animal and human material. After 96 h of immobilization the different stainability of Purkinje cells becomes more marked, which phenomenon can be as well explained with regard to the functional point of view. Similar differences, though less marked, were found also in neurosecretory cells of the nucleus supra-opticus of the rat and in the nuclear region of the ganglion semilunare Gasseri cells in man. Finally, the author refers to the relations between the Luxol blue staining method and Baker’s method employing acid haematoxylin for demonstration of phospholipids in certain kinds of nervous system cells, taking into consideration Kroon’s findi