The cells of the red microalgae are encapsulated within a sulphated polysaccharide in the form of a gel. The capsules are thinnest during the logarithmic phase of growth and thickest during the stationary phase, since the rate of production is higher than the rate of solubilization into the external medium (Ramus, 1972, 1986). During growth in a liquid medium, the viscosity of the medium increases due to the release of polysaccharide from the cell surface. Although it is believed that the capsule is homogeneous, it seems possible that the inner layer differs from the outer layer, as it does in the red macroalgae.