The osmotic properties of sulphoethyl-sephadex. A model for cartilage.

1. Observations are reported on the variation of the swelling of sulphoethyl-Sephadex C-50 and C-25, and of the partition of NaCl between solution and gel, with the concentration of NaCl. 2. The results were interpreted in terms of Manning's (1969) treatment of the interactions between polyionic polymers and simple electrolytes and of Flory's (1953) treatment of the swelling of gels. 3. The results indicate net inner osmotic pressures as high as 3.6x10(5)Pa (140 mosmolar=3.6x10(5)N/m(2)) in 0.15m-NaCl. 4. It is suggested that cartilage may have net inner osmotic pressure of the order of 10(5)Pa.