A PHYSIOLOGICAL THEORY OF COLOUR PERCEPTION

Abstract

IT is nowadays possible to record the discharge of the retinal elements directly by leading off to electrodes from more or less isolated fibres of the optic nerve. The electrical impulses following upon illumination are the physiological means of communication between the retina and the higher centers. They are amplified and led to an oscillograph for photographic recording and at the same time listened to in a loud-speaker. This is the technique for which the well-known work of Prof. E. D. Adrian and his collaborators originally laid a solid basis. For isolation of the fibres in the optic nerve a method of micro-dissection around the blind spot has been developed by Hartline¹ and a micro-electrode technique for picking up from the fibres inside the eye by Granit and Svaetichin². The latter method is a great deal simpler and faster than the former, and for this reason it is the natural instrument for a rapid survey of the colour properties of a large number of single or grouped units in the response of the eye to illumination with spectral light of known energy content. Mammalian eyes can be studied with the micro-electrode as easily as eyes of the cold-blooded animals, to which the technique of micro-dissection is limited if it is to be used for analytical purposes. The animal is anaesthetized, cornea and lens removed, and the micro-electrode inserted with the aid of a micro-manipulator under suitable optical magnification.