Based on previous work of the writer (2) this paper deals with the specification of dynamical systems via potential momentum and momentum fields, and setting out from the continuous motion formally identical with the meson→electron transformation, opens the study of systems of motions of a single particle defined bywhereFρσis not an antisymmetric tensor. Fields which, in addition to the usual electromagnetic effects, change the rest-mass of a particle moving under their action, and which are caused by the creation or destruction of electric charge, are proposed as the classical model for neutrino radiation.