Correlation between the morpho-functional organization of some portions of the visual analyser of chelonia and their ecology: I. Normal morpho-functional characteristics of the optic nerve and the tectum opticum.

Several methods (light optic, electron microscope and electrophysiological) were used to study the optic nerve and the tectum opticum of water turtles (two species) and of land tortoises (two species). As the result of study of the two levels of the visual analyser in four species of Chelonia three groups of signs of the morpho-functional organization were distinguished: signs common for the Chelonia under study; ecologically specific signs--common for water turtles and species-specific traits which are--different in species of the same ecological group. Specific features of structural-functional organization of the visually directed behaviour in Chelonia at the neuronal populations level were shown to correlate with the ecological features to a greater degree than with the systematic position of the species.