ABSTRACT
The diffusion of oxygen through preparations of the mesogloea of Calliactis parasitica (Couch) has been measured with a custom-built diffusion cell and an oxygen microelectrode. The mean value for Fick’s diffusion coefficient was 7·29 × 10−6cm2s−1 and that for Krogh’s diffusion constant 10·00 × 10−6cm3 oxygen per min per cm2 area and cm thickness at a pressure difference of 1 atmosphere, at 25 °C. Comparison with the rather few values in the literature for oxygen diffusion through biological materials indicates that mesogloea is similar to connective tissue. The mesogloea of Calliactis seems to present a fairly significant barrier to the diffusion of oxygen between the two cell layers, and this is discussed in relation to the route whereby the endoderm obtains its oxygen.
