A histological method for localization of an enzymic activity. The tissue or cell preparation overlays a gel that contains a chromophore- or fluorophore-labelled substrate, e.g. casein for a proteinase assay. After enzymic reaction, and washing or diffusing away of labelled products, the sample is coated with a photographic emulsion, exposed and developed to superimpose the histological sample on cleared areas in the labelled substrate that represent areas of enzymic activity.