Nucleic acid amplification reaction apparatus and method

An apparatus for performing a chemical chain reaction in a capillary tube, comprising:

• an elongated chamber having an input port and an output port and having a wire mesh across at least a cross sectional portion of the chamber;
• at least first and second fluid bypass pipes providing fluid flow paths around the chamber;
• a first thermostatted bath for maintaining the temperature of a body of fluid therein at a temperature suitable for causing denaturation to occur in a reaction mixture;
• a second thermostatted bath for maintaining the temperature of a body of fluid therein at a temperature suitable for causing annealing and extension reactions to occur in the reaction mixture;
• pumping means connected between the chamber and each of the baths for pumping fluid from each of the first and second baths to the chamber;
• valve means for selectively coupling a stream of fluid from one of the baths through the chamber while coupling another stream of fluid from the second bath through one of the bypass pipes, and then for coupling the stream pumped by the pumping means from the second bath through the chamber and coupling the stream pumped by the pumping means from the first bath through another one of the bypass pipes.