1. Department of Pharmacology and Toxicology, National Veterinary Institute. P. 0. Box 8146 Dep, 0033 Oslo 1, Norway;
2. Fridfjof Mehlum, Norsk Polarinsfitutf, P.O. Box 158, N-1330 Oslo Lufthaun, Norway;
3. Department of Zoology, University of Trondheim, N-70SS Draguoll, Norway;
4. Department of Fish Diseases and Aquiculfure, National Veterinary Institute, P.O. Box 813-6 Dep, N-0033 Oslo 1, Norway.