Simple Respirometer Spares. Comprising rates of absorption or evolution of gases by small organisms, during respiration. The apparatus consists of two stoppered boiling tubes connected by three-way taps to either limb of graduated manometer. One tube holds the organisms with a syringe for altering the level of liquid in the manometer during setting up. The other tube acts as a control thermo barometer. CO2 given off by the respiring organism is absorbed by potassium hydroxide in the experimental chamber resulting in a change in the level of liquid in the manometer tube. Complete with wire baskets for supporting organisms. Spare boiling tube.