1. Berde, B., Hollander, L., Undritz, E., and Zehnder, K. (1955). Schweiz. med. Wschr., 85, 936.
2. Fielding, J., Karabus, C., and Brunstrom, G. M. (1968). J. clin. Path., 21, 402.
3. O'Shaughnessy, M. C., and Brunstrom, G. M. (1965). Lancet, 2,9.
4. Hagberg, B., Wallenius, G., and Wranne, L. (1958). Scand. J. cli:. Lab. Invest., 10, 63.
5. Heist0, H., and Foss, 0. P. (1958). Ibid., 10, 102.