Most authors who have studied the whole visual system described the fiber connections between the different nuclear centers (Monakow, 1883, 1889; Probst, 1900; Minkowski, 1913, 1920, 1934; Kosaka and Hiraiwa, 1914; Put­ nam, 1926; Oshinomi, 1930; Papez and Freeman, 1930; Lashley, 1931, 1934a, 1934b, 1941; Barris and Ingram, 1933/34; Le Gros Clark and Penman, 1934; Waller, 1934; Chang, 1936; Gillilan, 1940; Le Gros Clark, 1942; Krieg, 1946a, 1946b, 1947; Nauta and Bucher, 1954; Hayhow et al. , 1962; Lund, 1966; Mon­ tero, 1968). The histogenetic and cytogenetic differentiation of the various components of the visual system has been treated in numerous individual studies mostly on the cerebral cortex and the retina and to a lesser degree on the superior col­ liculus and the lateral geniculate body, however, it has not yet been investigated under the aspects of developmental interactions of a functional system on the basis of comparing the development of the different brain parts involved with re­ spect to the establishment of a functionally interrelated system. The first concepts of the histological differentiation of the neural tube and parts of the more advanced central nervous system were based on the classical neuroblast-spon­ gioblast-theory of His (1889, 1904), Cajal (1911, 1960) and Lorente de No (1922, 1933, 1949). The development of the definitive cerebral cortex with its 6 laminae according to Tilney (1933) was attributed to three successive cell migrations which form the supragranular, granular and infragranular layers.