A note on the copper content of sea-urchin semen and sea water.

INTRODUCTION The addition of copper salts to dense suspensions of unwashed sea-urchin spermatozoa in sea water markedly stimulates the O2 uptake of the suspension (Rothschild & Tuft, 1950). An investigation of the Cu content of sea-urchin semen and seminal plasma was therefore of interest and is the subject of this note. At the same time the coelomic fluid of Echinus esculentus and sea water were analysed for the same metal. The only recent investigation of the Cu content of sea-urchins was carried out by Webb(io,37). He found that the coelomic fluid of E.esculentus contained 1-04 /ig./ml. Cu, eighty times as much as the sea water (Loch Ine) from which the sea-urchins were taken. The Cu content of this sea water was 0-013 /ig./ml., assuming a chlorinity of 19%. According to Sverdrup, Johnson and Fleming (1942), the Cu content of sea water varies from o-ooi to o-oi /ig./ml.