Abstract: A cell separator is provided that includes apparatus for automatically controlling the cell separation process. Particularly, a plurality of valves are responsive to a data processor assembly for controlling the path of fluid flow through the cell separator. A plurality of sensors are provided for providing sensor signals indicative of the density of fluid flowing through the cell separator. The microprocessor is responsive to the sensor signals for controlling the flow and operation of the cell separator. A parastaltic pump is responsive to the microprocessor assembly for controlling the speed and direction of fluid flow through the system. A stirplate assembly is responsive to a drive signal from the data processor assembly for controllably agitating the contents of a column. The data processor assembly is further responsive to the sensor input to provide the valve control signals and pump control signal to control the concentration of selected cells that are collected.