Optical characteristics of ommatidia in the complex eye of Musca

Abstract

Optical characteristics of the dioptric system in the ommatidia of Musca have been analysed by use of “antidromic illumination” of the eye. The results indicate that the distal endings of the rhabdomers terminate near the focal plane of the dioptrics and that the quality of the lens is high enough to resolve some details of their shape. — Using optical methods it has been possible to confirm directly that the optical axes of 7 individual rhabdomers from 7 different ommatidia all converge to a common point in the distant surroundings. This is a characteristic for compound eyes of the “neural superposition” type. — The results are discussed on the basis of the hypothesis that the Musca eye is composed of two functionally different subsystems: One system (D) with high absolute sensitivity and low spatial resolution consisting of the sense cells no. 1 to 6, and a second system (H) with high spatial resolution and low absolute sensitivity composed of cells no. 7 and 8.