Race tubes are hollow glass tubes that are partially filled with agar and inoculated with fungus. Circadian rhythm researchers expose the inoculated tubes to different regimens of light and dark cycles to study the effects of this periodicity on the fungus. These tubes were originally photographed against a black background. Copy lighting was used and the angle of the lights was adjusted so there would be no bothersome reflections off the tubes. The black background was replaced in Photoshop with the blue gradient.