Pipette means

Claim 1

Pipette means comprising: a flexible tube connected to a pipette tip for liquid flow therebetween, said tube being of substantially cylindrical, elastomeric form with a ratio of wall thickness to internal diameter not less than about 1:2 to maintain compression and expansion thereof substantially uniformly circumferential; expelling means arranged to apply pressure to the outside surface of said tube to compress said tube and reduce its internal volume tending to expel liquid from said pipette tip; and aspirating means arranged to relieve pressure from the outside surface of said tube to allow expansion of said tube and its internal volume so that liquid may be drawn into said pipette tip; and wherein said aspirating and expelling means includes a source of fluid pressure, a reservoir, and valve means operatively coupling said source and said reservoir, said valve means having a first position wherein pressure is removed from the cylindrical tube to aspirate a sample into the pipette tip while said reservoir is simultaneously charged with fluid pressure from said source, and a second position wherein pressure is applied to the cylindrical tube by applying said charged pressure in said reservoir to at least assist in expelling the sample from the pipette tip, said aspirating and expelling means thereby being operable by the application and relief respectively of said fluid pressure to and from said cylindrical tube.