THE recent communication of Tewari and Bourne1 on the neurokeratin network of peripheral nerve fibres is valuable not only for its intrinsic content but also because it validates the histological procedures, findings and arguments derived therefrom, by which it was concluded that neurokeratin formations are part of the architecture of the nerve fibres and not artefacts2,3. It is sad to think that Nageotte4, who saw the structures in peripheral nerve fibres described by me2,3 and by Tewari and Bourne, looked on them as artefacts. One of the strongest anatomical arguments against the notion of artefact is that the disposition of neurokeratin in spinal cord axons and in the preterminal axons found in spinal cord, in brain stem and in cerebral and cerebellar cortices is quite different from that characteristic of peripheral nerve trunks, even although the material examined was fixed and prepared for sectioning under strictly comparable conditions in all instances.