3dsmax particle flow, spawn


I am trying to create a flow in max, the prolem is that i want to see the trail that particles leave behind in order
to change me flow. I am trying to use spawn but i can not find a way to show the particle’s trajectory as lines.
any help would be valuable.
p.s. i know how to create lines at the end using a script. i can not see trajectories as lines while the flow is on work…
thank u. merry xmas.