The invention provides a method of printing, onto a substrate (12), an array (14) of spots of reagent compositions for use in a chemical and/or biochemical analysis. The method includes displacing an array of reagent composition containing capillary tubes (22) arranged alongside one another from an inoperative position to an operative position in which open ends of the capillary tubes (22) simultaneously impinge against a substrate and thereafter displacing the array of tubes (22) from the operative position back to the inoperative position. The invention extends to a printing apparatus (10), a method of printing a layered array of spots of reagent compositions, a method of introducing reagent compositions into the tubes, a reagent introducing device for introducing reagent compositions into the tubes and a printing installation which includes the printing apparatus (10) and the reagent introducing device.