Editing Potometer (section)

==Design==

Potometers come in a variety of designs, but all follow the same basic principle.
*'''A length of capillary tube'''. A bubble is introduced to the capillary; as water is taken up by the plant, the bubble moves.  By marking regular gradations on the tube, it is possible to measure water uptake.
*''' A reservoir'''. Typically a [[funnel]] with a tap; turning the tap on the reservoir resets the bubble.  Some designs use a [[syringe]] instead.
* '''A tube for holding the shoot'''. The shoot must be held in contact with the water; additionally, the surface of the water should not be exposed to the air.  Otherwise, evaporation will interfere with measurements.  A [[rubber bung]] greased with [[petroleum jelly]] suffices.