RHEOLOGICAL BEHAVIOUR OF CHARA AUSTRALIS

The viscoelastic behaviour of the cell wall of Chara australis was studied by following the relaxation of stress after deformation by (a) imposing a "step function" change in length and (b) varying the osmotic pressure of the external bathing solution, and hence changing the turgor pressure within the cell. It was found that (i) a sudden decrease in the original elongation of the cell produced an unexpected transient increase in stress and (ii) an interaction between water movement in the cell due to osmosis and stress relaxation produced a maximum stress with respect to time. The results are discussed in terms of a cross-linked amorphous polymer model.