01490naa a2200181 a 450000100080000000500110000800800410001910000200006024500800008026000090016052009940016965000110116365300120117465300250118665300260121170000170123777300540125410548251997-12-29       1952    bl ---       0--  u    #d1 aWILLIAMS, H. D.  aThe inheritance of horns and their modifications in polled hereford cattle.  c1952  aFrom a review of the literature three theories of the inheritance of horns and horn modifications stand out: (1) one pair of alleles is involved-P and p; (2) two pairs of alleles-P andp, and SC and sc; and (3) four pairs of alleles-the theory of White and Ibsen, which best fits the data. One revision of this theory is suggested-changing the scurred factor to a recessive gene. Several conjectures have been made as possible explamations of abnormal cases appearing in the literature and cases not yet studied. The variety of ways in which these cases could be brought about indicate that the inheritance of horns and rudimentary horns is not nearly so simple as a four gene theory would appear to make it. Possible rare genes and irregular modifying factors make the interpretation of data most difficult. Other difficulties in studying the mode of inheritance arise from the fact that the population is so heterogeneous, and abnormal population ratios often appear in the samples taken.  aBovino  aCattlle  aInheritance of horns  aMelhoramento genetico1 aWILLIAMS, T.  tThe Journal of Hereditygv. 43, p. 267-272, 1952.