a aera ET 10 for counting and a 500 ml sample saved for possible future use. To each of the 100 ml samples 5 ml of saturated sodium carbon- ate was added. The precipitate was collected on 14-inch Milli- pore HA paper in a Millipore filter and counted. By this method naturally occurring «10 normally present in sea water to the extent of about 600 d/m, is eliminated from the portion which is counted. Radiocesium is also lost in the filtrate but ac- counts for less than one per cent of the total activity at the time of collection. The water samples processed at EMBL were treated in a similar manner except that a 500 ml sample was filtered and only one 100 ml sample was prepared for counting. Fish Samples: Time and facilities were not available to collect fish in numbers. However, three flying fish were found on deck and taken as samples, Larval forms and small fish were captured in the plankton nets but were not processed separately. In an attempt to increase the take of flying fish a section of white canvas was stretched on the starboard side near the after gun mount. A light was kept burning at night to illuminate the canvas. The three flying fish were frozen aboard ship. and muscle were processed at the EMBL. The liver These tissues were dried for 12 hours at about 100°C on 14-inch plates, ashed at 500°C (3 hours), slurried with alcohol and fixed to the plate with 0.5 per cent solution of formvar in ethylene dichloride, and then counted. Continuous Monitoring of Water: A probe for continuously +; oy Py *