Abstract: A novel gas investigation apparatus is provided herein. Such gas investigation apparatus includes a hollow cylindrical transparent barrel having a lower inlet and an upper outlet. A plunger is slidably fitted in a leak-proof manner within the barrel. A gas inlet tube having a lower and upper inlet and outlet is provided within the plunger and extends along the longitudinal axis of the plunger. A longitudinally-extending, transparent heat transfer jacket surrounds the hollow, barrel. An upper valve is connected to the upper outlet of the barrel by means of a zero dead-space, butt-end connection. A selective entry is provided through the upper valve for admitting a study liquid or a tissue suspension into the barrel. A lower valve is connected to the lower inlet of the gas inlet tube by means of a zero dead-space, butt-end connection. An inlet conduit is provided for the selective introduction of test gas, or carrier gas, or flushing gas into the gas inlet tube through the lower valve.