Abstract: An dispenser characterized by provision for use of a replaceable needle and a prefilled cartridge.The dispenser comprises an elongated body separable into two body sections, with the front end section adapted to contain a prefilled cartridge and with provision at the front end for mounting a needle removably thereon.The back end section contains the operating mechanism shown by FIG. 10 to convert the longitudinal movement of a pushable element into unidirectionally rotary movement, then into longitudinal movement of a piston rod that acts to expel fluid through the needle.A multipurpose cap is protective of the needle end when mounted on the front end, and is an operating member when mounted on the rear end, as is illustrated by FIGS. 1 and 2.