An air displacement pipette comprising a tip mounting shaft (112, 610, 1110) having an interior surface (618, 1118) and a distal end (120, 2236), a piston (612, 1112, 1516, 1718, 1918, 2234) mounted for axial movement within the shaft and having a distal face (620, 1120), and a pipette tip (114, 210, 410, 710, 910) mountable to the tip mounting shaft, the pipette tip having a generally elongated tubular configuration with an open proximal end (213, 713) and a tapered open distal end (312, 812), and the shaft and piston together defining an interior space between the piston and the interior surface of the shaft; characterized by: the pipette tip comprising a mount portion (212, 412, 712, 912) and a liquid handling portion (220, 720), wherein the mount portion includes the open proximal end of the tip and has an inward-facing sealing region (214, 414, 714, 1414, 1716) adapted to seal against the piston, wherein the liquid handling portion includes the tapered open distal end of the tip, and wherein the mount portion is adapted for sliding insertion into the distal end of the shaft; the mount portion of the tip extending into the interior space between the piston and the shaft, the piston penetrating the open proximal end of the pipette tip, and the sealing region of the pipette tip forming an air tight seal against the piston when the tip is mounted on the shaft; a cooperative_structure (617, 1117) on the pipette tip-mounting shaft (112, 610, 1110) and pipette tip (114, 210, 410, 710, 910) for preventing the tip from moving axially with respect to the pipette when the piston (612, 1112, 1516, 1718, 1918, 2234) is moved through the air tight seal between the piston and the tip; and the piston being axially movable within the mount portion of the tip, wherein an air volume only within the pipette tip is displaced to move liquid in and out of the pipette tip by the axial movement of the piston. the pipette tip comprising a mount portion (212, 412, 712, 912) and a liquid handling portion (220, 720), wherein the mount portion includes the open proximal end of the tip and has an inward-facing sealing region (214, 414, 714, 1414, 1716) adapted to seal against the piston, wherein the liquid handling portion includes the tapered open distal end of the tip, and wherein the mount portion is adapted for sliding insertion into the distal end of the shaft; the mount portion of the tip extending into the interior space between the piston and the shaft, the piston penetrating the open proximal end of the pipette tip, and the sealing region of the pipette tip forming an air tight seal against the piston when the tip is mounted on the shaft; a cooperative_structure (617, 1117) on the pipette tip-mounting shaft (112, 610, 1110) and pipette tip (114, 210, 410, 710, 910) for preventing the tip from moving axially with respect to the pipette when the piston (612, 1112, 1516, 1718, 1918, 2234) is moved through the air tight seal between the piston and the tip; and the piston being axially movable within the mount portion of the tip, wherein an air volume only within the pipette tip is displaced to move liquid in and out of the pipette tip by the axial movement of the piston.