Puromycin injected intracerebrally in rats renders affected neurons extremely argyrophilic, which makes it possible to demonstrate their fine geometry by the aid of a reduced silver impregnation procedure. The technique shows promise as a directed Golgi-like method. The abortive action of puromycin on protein synthesis produces a multitude of argyrophilic peptide fragments, which are subsequently transported throughout the neuron as protein-like moieties. It is hypothesized that these fragments serve as nucleation points for subsequent silver deposition.