Aberrant Optic Nerve Fibres Found between Retina and Hexagonal Cells.

NERVE fibre bundles of different size aberrant ,from the optic nerve escape according to Ida Mann (1937) from the confines of the optic stalk, and become free in the orbit. They originate at an early stage (about 17 mm. length) when the nerve fibres find their way from the ganglion cells into the optic stalk. Anatomically they are a division of the main stem of the optic nerve in its orbital or intracranial course. In the case of Sneed (1914) which I have observed with this author the right optic nerve was split in front of the chiasma into a smaller temporal and a thicker nasal thread. Each had its own sheath.' In the case of Scheerer (1923) the optic nerve was considerably broadened behind the cribriform plate. -Histologically this author could prove that the nerve fibres had left the optic nerve through gaps in the pia in the shape of bundles of the optic nerye are described by E.' Fuchs, Ganser, afid others. Von Szily (1924) has modelled such aberrant fibres in his reconstruction of the eyes'of rabbit embryos of a coloboma strain. The aberrant bundles appear at the outside of the eye, but are to be found among the cells of the pigmented epithelium as well. Nothing is known so far about aberrant nerve fibres of the optic nerve closely-behind the retina. As I have observed two cases of 'entirely different aetiology and there are interesting biological questions linked with this phenorpenon, the anatomical findings should be mentioned.