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Dear Glen,
The solutions are gravity-fed via independent tubes from the base of 50 ml 
syringes suspended about 50cm above the microscope stage. The tubes are 
identical and are connected to electrical on-off valves (General Valves). The 
tubes meet at a manifold about 15 cm from the output. In the case of the 
video the output is directly onto the top of a fixed-preparation (Convallaria) 
slide which was mounted directly onto the fixed platform of the microscope. 
The output tube was about 2 mm from the objective at the level of the slide. 
The suction was similarly sighted about 2 mm from the objective at an angle of 
180 degrees to the input. The suction was from a bottle (2 L) maintained a 
low pressure with a high frequency low volume pump. The only oscillations that 
occur within the system are surface tension effects on the suction when air 
mixes with the water in the output lines - this occurs all of the time and 
sounds like a child sucking through a straw from an empty glass of lemonade!
I doubt that it is movement. I guess I would need a force transducer mounted 
on the slide to prove that.
Greetings,
Christof