  In the paper by J.\L uczka {\em et al.} ({\em Europhys. Lett.}, {\bf 31}
(1995) 431), the authors reported by rigorous calculation that an additive
Poissonian white shot noise can induce a macroscopic current of a dissipative
particle in a periodic potential -- even {\em in the absence} of spatial
asymmetry of the potential. We argue that their main result is an obvious one
caused by the spatially broken symmetry of a probability distribution of the
additive noise, unlike the similar result caused by chaotic noise which has a
symmetric probability distribution ({\em J.Phys.Soc.Jpn.}, {\bf 63} (1994)
2014).
