Diseases of the respiratory tract may be related to the altered rheological properties of the respiratory tract mucus and to the altered ciliary shearing capabilities. Flow curves are presented showing that mucus has thixotropic properties and has discrete yield points. Mechanical models of cilia constructed to perform oscillatory motions comparable to thosein vivohave been studied as shearing elements in a modification of the Hoppmann‐Miller Rotational Fluid Flow Generator. A description of those modifications is presented with special attention being given to the design of special cams needed to carry out the proper oscillation of the simulated cilia. Flow trends and particle path lines are described for the mechanical cilia oscillating in and out of phase. Linear velocity of small particles injected into the flow is measured as a function of frequency of oscillation. Finally, some interesting questions are raised pertaining toin vivociliated activity in light of experience gained with the apparatus.