1. Ashman, R. (1942). Amer. Heart J., 23, 522.
2. Barker, P. S., Johnston, F. D., and Wilson, F. N. (1937). Ibid., 14, 82.
3. Chamberlain, F. L., Scudder, J., and Zwemer, R. L. (1939). Ibid., 18, 458.
4. Personal communication;Chapman, C.,1945
5. Feil, H. (1936). Amer. Heart J., 11, 173.