  It is argued by the author that the canonical form of the quark
energy-momentum tensor with a partial derivative instead of the covariant
derivative is the correct definition for the quark momentum and angular
momentum fraction of the nucleon in covariant quantization. Although it is not
manifestly gauge invariant, its matrix elements in the nucleon will be
non-vanishing and are gauge invariant. We test this idea in the path-integral
quantization by calculating correlation functions on the lattice with a
gauge-invariant nucleon interpolation field and replacing the gauge link in the
quark lattice momentum operator with unity, which corresponds to the partial
derivative in the continuum. We find that the ratios of three-point to
two-point functions are zero within errors for both the u and d quarks,
contrary to the case without setting the gauge links to unity.
