Abstract: 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.