Apoplastic water movement on the electron microscopic level was studied by means of PbS particles produced in situ after exposing gametophytes which were immersed in Pb-EDTA to H2S. The presence of PbS particles in the tissue is used to evaluate the apoplastic conduction of water. All cell walls of all the tissues appear to conduct water. The heavy mass of cell-wall material contributes to the radial conduction of water to the hadrom. Absorption of water through the aerial surface of the gametophyte is more efficient than through the rhizome.