A package (10) for storing and dispensing a flowable material includes acontainer body (11) having an inlet end(20) and an outlet end (21). The container body (11) is configured to hold aquantity of the material and has a piston (30) receivablewithin the intlet end (20) and movable within the container body (11, 12). Atleast a portion of the piston (30) is selectivelypermeable to a selected medium.
