Abstract
Using a dynamic method which enabled simultaneous measurement of the cell length and turgidity of Characean internode, a rectilinear correlation was found between them, within 4 sec or so immediately after the step change in outer osmotic pressure. By studying the time dependency of these parameters, the velocity of the water flow V across the cell membrane can be observed instantaneously. Further, the absolute water conductivity Lp can also be estimated from V and the shift in water motive force across the membrane. Then the difference in Lp was accomplished by comparing the effluxing and influxing situations through changing πe from the holding osmotic pressure of 150 mM mannitol solution to either 200 mM or to 50 mM. There was no significant difference in Lp between them suggesting that the membrane itself is not a rectifier for the water flow.
