what is this part, 94 e320
 

almost finished replacing my wiring harness, and this thing came loose, the white tube. i know how it connects to the front of the engine,close to where the arrow is, but where does it go and where does it end and connect? what is it called. thanks guys

Its the vacuum supply hose for the switchover valve for airinjection, hose plugs in to rubber tee at top of switchover valve, other end goes to intake manifold, behind waterpump area, there is a y hose that it plugs into for supply source