An elongate flexible syringe for the injection of fluids is formed with an elongate flexible tube and an elongate flexible rod sized to move through the bore of the tube to control the discharge of liquid in the tube. A cartridge is provided to store the flexible rod in a coiled form. The flexible rod is advanced by a syringe actuator having a control housing to which the cartridge is conveniently mounted. The actuator includes a mechanism for energizing the flexible rod and cause it to advance in a precisely controlled manner. A device for detecting motion or the absence of motion of the flexible rod is described so that the proper operation and emptying of the tube can be continually monitored. The elongate flexible syringe is particularly convenient to be carried by a person for the timed regulated injection of medicine such as insulin.