THE CELL SAP OF PROCHLORON (PROCHLOROPHYTA)

Living cells of the symbiotic prokaryotic alp Prochloron sp. are spher ical, tightly inflated by osmotic pressure, and highly refractile. Whe n they die they shrink appreciably, become more translucent, and relea se a pink exudate with an absorption maximum around 334 nm and a refra ctive index (RI) considerably above that of seawater. Small samples of such exuded sap were analysed. Estimated by melting-point depression, its osmotic pressure (OP) is about 30% above that of seawater. Glucos e and maltose account for much of increase in OP, and proteins (includ ing nucleoproteins) and oligosaccharides for the RI augmentation value s observed.