Regarding hemodialysis membranes as layers packed with uniform polymeric particles, the size of the particles is determined using the Kozeny-Carman equation. Diameter of the spheres forming cellulosic membranes is the same order as the size of primary polymeric particles determined by electron microscopy in a previous article. Pore radii of the membranes calculated by the Kozeny-Carman equation are in agreement with those determined by the tortuous capillary pore model. The result suggests that an estimate of a pore radius of a membrane is feasible by the Kozeny-Carman equation only with water permeability of the membrane. Intramembrane diffusion coefficients of vitamin B-12 calculated from an equation derived from the analogy of heat conduction in heterogeneous media consisting of a continuous phase and particles are larger than the experimental values. The result suggests the failure of the analogy between heat conduction and diffusion of vitamin B-12 in a heterogeneous medium.