1. Johnson, F. H., and Flagler, E. A., Science, 112, 91 (1950).
2. Fenn, W. O., in The Physiology and Medicine of Diving (edit. by Bennett, P. B., and Elliot, D. H.), 36 (Baillière, Tindall and Cassell, London, 1969).
3. Regnard, P., Recherches Expérimentales sur les Conditions Physiques de la Vie dans les Eaux (Masson, Paris, 1891).
4. Cattell, M., Biol. Rev., 11, 441 (1936).
5. Miller, K. W., Paton, W. D. M., Streett, W. B., and Smith, E. B., Science, 157, 97 (1967).