It is shown (1) that Lanczos’s quaternionic formulation of Dirac’s equation does not lead to a solution of the problems that plague the standard spin 3/2 theory based on the Rarita-Schwinger equation, but (2) that the four-component solutions to the quaternionic generalization of Dirac’s equation proposed by Lanczos in 1929 may provide a consistent theory for spin 3/2 particles, although at the...