Respirometer is a device which is used to measure the amount of oxygen consumed by the germinating seeds. Plants generate oxygen and exhale carbon dioxide. This instrument contains limewater and germinating seeds. The carbon dioxide excreted by the seeds are absorbed by the limewater which creates a slight vacuum in the apparatus. This vacuum will move a drop of detergent in the glass tubing towards inside of the Respirometer. This movement of detergent is will be measured by tape in millimeters. This measure will give the amount of oxygen consumed by seeds.
Thus, limewater must be included in the experiment.