Paleomagnetism: United States-Japan committee on scientific cooperation.

production. 8) The cells must be approved by the National Control Authority. The data obtained in a number of field trials of vaccine produced in one such human diploid cell strain is sufficiently encouraging to warrant continued efforts. Over 200,000 persons have now received vaccines produced in the human diploid cell strain WI-38. Vaccines against poliomyelitis, adenovirus type 4, measles, rubella, and rhinovirus, some administered orally and others parenterally, have produced no known untoward effects. FRANK T. PERKINS Chairman, Cell Culture Committee, Division of Immunological Products Control, Medical Research Council Laboratories, Holly Hill, Hampstead, London, N.W.3, England LEONARD HAYFLICK Secretary, Cell Culture Committee, Wistar Institute, Philadelphia, Pennsylvania