Pipetting and diluting apparatus including an interchangeable syringe pump of predetermined volume capacity and a stepper motor for driving the syringe piston at a selected speed for dosing a selected volume of fluid. The piston stroke is calculated from the syringe volume capacity and the volume of fluid to be dosed. Control means controls the acceleration and deceleration characteristic of the piston in accordance with an exponential function dependent upon the selected piston speed and the syringe volume capacity.
