  It is shown that the equations of motion of a test point particle with spin
in a given gravitational field, so called Mathisson - Papapetrou equations, can
be derived from Euler - Lagrange equations of the relativistic pseudomechanics
-- relativistic mechanics, which side by side uses the conventional (commuting)
and Grassmannian (anticommuting) variables. In this approach the known
difficulties of the Mathisson - Papapetrou equations, namely, the problem of
the choice of supplementary conditions and the problem of higher derivatives
are not appear.
