Paramecium multimicronucleatum - Video of the Contractile Vacuole Complex. Effects of applying suction to an in vitro CV. Effect of suction on the rounding/relaxing cycle of an in vitro CV of Paramecium. When a suction micropipette is placed against the membrane of the in vitro CV and a small amount of suction is applied the CV will immediately undergo rounding even though it is still in its relaxing phase. Suction induced an extra rounding irrespective of the time in the rounding/relaxing cycle that suction was applied. Suction always produces maximum rounding. A DVD resolution version of this is available at CIL:10414.