We formulate Lorentz, group representations in which ordinary complex numbe
rs are replaced by linear functions of real quaternions and introduce dotte
d and undotted quaternionic one-dimensional spinors. To extend to parity th
e space-time transformations, we combine these one-dimensional spinors into
bi-dimensional column vectors. From the transformation properties of the t
wo-component spinors, we derive a quaternionic chiral representation for th
e space-time algebra. Finally, we obtain a quaternionic bi-dimensional vers
ion of the Dirac equation.