To measure gas evolved or absorbed by living materials or tissue extracts. A respirometer bulb with a small water reservoir at the bottom and hollow ground glass stopper at top in the neck with a hole which can be closed or opened by turning the stopper, a graduated burette opening out of the bulb which connects to a leveling tube via a rubber tubing. Respirometer chamber 50 mm dia, burette 180 x 20 mm graduated 0 to 25 ml and 100 to 75 ml, with special clamp for fixing to a 12 mm dia rod.