[Wall labyrinths in the sporophyte of Polytrichum]

In the foot of the Polytrichum sporophyte the outer walls of the peripheral cells are coated with a labyrinth. In the outer 4-6 cell layers protuberances arising from the lamellated cell wall were found which are interpreted as initial stages of the labyrinth. In Polytrichum formosum there is a correlation between the lysis of the cell wall and the initiation of new protuberances. In the outer cell layers the protuberances increase more and more and fuse. In the external cells large aggregations of wall substances are deposited, in which the protuberances are seen as electron dense cores. In the wall substances of the external cells there are large inclusions of an electron dense material, the accumulation of which seems to be in relation to the growth intensity of the sporophyt. Some structures enclosed in the wall material seem to be membraneous elements.