BIOLOGICAL RHYTHMS, NOISE, AND ASYMMETRY IN THE PUPIL‐RETINAL CONTROL SYSTEM *

In several years of study of the pupil reflex to light (considered as a servomechanism), we have had occasion to analyze mathematically several types of oscillatory or fluctuating phenomena. Three experimental examples are selected to illustrate different aspects of biological rhythms. Details of much of this work can be found in a review1 on the pupil which treats linear, continuous non-linear, and asymmetrical non-linear aspects of both the pupil and the retina, which must be included in the pupil system. Finally, some new work on asymmetrical characteristics of retinal adaptation will be presented to illustrate the complexity of the neurological pupil control system.