  The possible nature of the nonlinear evolution of quantum systems is explored
from the point of view of nonlocal effects under the conditions of EPR paradox.
It is shown that both stochastic and deterministic mechanisms of nonlocal
evolution should consider a quantum particle as a material field in order not
to contradict special relativity. It is assumed that there is an experiment
allowing to find out which of the mechanisms of nonlinear evolution is realized
in nature
