PURPOSE: To draw-in and eject a predetermined quantity of liquid by using a tube which has one open end and another closed end, inside volume of which corresponds to the predetermined quantity and which is rotable around an axial line so that the tube is fully filled with the liquid from the open end thereof when the tube is rotated in one direction and is fully emptied of the liquid when the tube is rotated in the opposite direction.

CONSTITUTION: A helical hollow tube 10 has a central axis 11 of symmetry, is closed at an upper end 15 and is opened at a lower end 16. When the lower end 16 of the tube 10 is immersed in the liquid, a small quantity of the liquid enters the tube 10 by capillary phenomenon. When the tube 10 is rotated in one direction, one component of centrifugal force acts on the liquid in the tube 10 to make the liquid ascend in the tube 10. When the tube 10 is rotated in the opposite direction, the centrifugal force acts on the liquid in the tube 10 to make the liquid discharge therefrom and the liquid descends and is ejected.