apparatus is provided to feed controlled quantities of a catalyst slurry to an olefin polymerization reactor in a controlled time sequence . the apparatus includes a feed line for continuously feeding an inert hydrocarbon liquid such as hexane or isobutane to the reactor . a bypass loop is provided in the feed line and is equipped with auxiliary apparatus to charge the loop with a predetermined quantity of catalyst slurry . at preselected timed intervals , the hydrocarbon feed is fed through the bypass loop to sweep the charge of catalyst slurry to the polymerization reactor .