  We study Siegel superparticle moving in $R^{4|4}$ flat superspace. Canonical
quantization is accomplished yielding the massless Wess-Zumino model as an
effective field theory. Path integral representation for the corresponding
superpropagator is constructed and proven to involve the Siegel action in a
gauge fixed form. It is shown that higher order fermionic constraints intrinsic
in the theory, though being a consequence of others in $d=4$, make a crucial
contribution into the path integral.
