Abstract: A development unit for a reproduction apparatus wherein the development unit contains marking agents by means of which prints are made. As a result of making prints, the quantity of marking agents in the development unit decreases. If this quantity decreases below a specific level, then marking agents are fed from a reservoir to the development unit. If at a specific moment circumstances result in a large quantity of marking agents being consumed in a short interval of time, then since resupplying the development unit takes some time there is a momentary a shortage of marking agents in the development unit which is undesirable. By supplying marking agents when a gradient of toner consumption exceeds a specific value, a future shortage is anticipated and the occurrence of a situation in which a shortage of marking agents occurs is considerably reduced.