Abstract: Apparatus for storing and dispensing pigmented marking particles into the development mechanism of a reproduction apparatus. The storing and dispensing apparatus comprises a cartridge including a housing for storing pigmented marking particles, and an elongated opening in the housing through which such marking particles may be dispensed. A cover is removably secured to the cartridge housing to seal the housing opening to prevent contamination of the environment by escape of such marking particles through the opening. The cover, in the preferred embodiment being a flexible sheet member, is selectively removed from sealing relation with the cartridge housing opening and held adjacent to the cartridge away from exposure to the environment when the cartridge is located relative to the development mechanism, whereby marking particles may readily be dispensed into the development mechanism through the housing opening and contamination of the environment is substantially prevented.