1 King, Helen Dean, and Castle, W. E., "Linkage Studies of the Rat," Proc. Nat. Acad. Sci., 21, 390-399 (1935). 2 King, Helen Dean, and Castle, W. E., "Linkage Studies of the Rat, II," Ibid., 23, 56-60 (1937). 3 Castle, W. E., and King, Helen Dean, "Linkage Studies of the Rat, III," Ibid., 26, 578-580 (1940). 4 Castle, W. E., "On a Method for Testing for Linkage between Lethal Genes," Ibid., 25...