Perineuronal nets could be visualized with some Golgi methods in the rat's brain. Nets were seen in telencephalic, diencephalic and mesencephalic structures covering somata and proximal dendrites of different neuronal types. Some nets could be found originating from microglia cells. In most cases their origin is not recognizable. These perineuronal nets seem to be identical with "Golgi nets" of late anatomists, which played an important role in the discussion between recticularists and neuronists. Some aspects of their possible functional significance are discussed.