The apparatus described enables one to feet a magnified image of cells making 2,000-3,000 revolutions per min. at 10 cm; from the centrifugal axis. The cells are mounted on a slide damped to the centrifuge arm. The source of light is fixed above the slide. Light passed through the slide into an ordinary microscope objective is then diverted by totally reflecting prisms to the eyepiece fixed above the centrifuge axis. By lighting cells for a few micro seconds every time they reach a certain point in revolution, they appear stationary and their contents show effects of centrifugal force. A special Hg lamp is described.