Abstract
A modified micro-respirometer employing the differential volumeter principle, and mechanical accessories for the same, are described. The apparatus enables addition of solutions to be made to the biological material during the experiment. It is of a high sensitivity, a drop movement of 1.0 mm. indicating a volume change of about 0.06 c.mm. It may be used with very small amounts of biological material, provides for convenience in manipulation) and allows readings to be made at 1 minute intervals. Typical results on plant tissue and protozoa are given.