Introduction

Abstract

In the 1820-ies in Germany a much notified court proceeding became of great importance for the development of sensory physiology. A prominent citizen had been attacked and beaten one night by a political enemy and subsequently sued him for damages. In the court the judge asked the plaintiff: “In the report you say that the night was so dark that you could not see your hand in front of your face. How could you tell that it was the accused who attacked you?” “Your Honour”, said the plaintiff, “it was very easy; in the lightning which occurred when he hit me in the eye I easily recognized the evil face of the accused”. This created a fierce debate in the newspapers whether cat’s eyes could radiate light and Johannes Müller who originally was a comparative anatomist was brought into the discussion. He performed experiments on the eye and the ear which led him to formulate his doctrine of the ‘specific nerve energies’ in 1826. Ever since then the problems of specificity of the sensory cells and the sensory nerve fibres has been one of the main questions of sensory physiology. When in 1867 Lovén in Sweden and Schwalbe in Germany discovered the taste buds of the tongue and Blix in 1882 the warm and cold spots in the skin the idea developed that Müller’s doctrine should be extended even to the qualities of sensation. In fact Helmholtz’s general idea of colour vision was founded on this basic principle.