Evidence assembled since the first comprehensive description of "axonal flow", by deformation analysis, electron microscopy, cinemicrography, and microrheology, has confirmed that the axon of the mature neuron is (a) a semisolid column; (b) in cellulifugal motion at about 1 mum/min (1 mm per day); (c) continuously reproduced at its perikaryal base; (d) propelled by a microperistaltic pulse wave in its surface; and (e) undergoing internal dissolution at the nerve ending. The axon thus "flows" as a structural entity ("axonal flow"), in contradistinction to fast "intraaxonal transport" of molecules and molecular assemblies along internal routes and by mechanisms that are still unknown.