| Table | Nature of mating (parental | Nature of +------+------+------+------+-----+-----+------+------+------+------+ | No. | nostril). | mating. | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | +-------+------------------------------+----------------+------+------+------+------+-----+-----+------+------+------+------+ | 45 | High × high | D × D | 1.7 | 1.7 | 0.8 | 0.8 | 5.0 | 4.2 | 6.7 | 23.5 | 32.8 | 22.7 | | 46 | High × low | D × R | 23.2 | 34.0 | 16.1 | 12.5 | 3.6 | 7.1 | 1.8 | 1.8 | ... | ... | | 47 | Heterozygous × low | DR × R | 43.4 | 26.4 | 35.9 | 3.8 | 7.6 | ... | 1.9 | ... | ... | ... | | 48 | Heterozygous × heterozygous | DR × DR | 21.5 | 33.3 | 20.5 | 4.8 | 5.0 | 4.3 | 2.1 | 3.1 | 4.1 | 1.2 | | 49 | Do. | F2(DR × DR) | 17.3 | 25.2 | 19.0 | 8.0 | 5.9 | 1.6 | 2.8 | 5.8 | 8.4 | 6.1 | | 50 | Heterozygous × high | DR × D | 16.4 | 21.3 | 16.4 | 8.2 | 6.6 | 1.6 | 3.3 | 13.1 | 9.8 | 3.3 | | 51 | Do. | DR × DD | 11.1 | 15.1 | 11.4 | 4.7 | 6.1 | 3.8 | 3.6 | 14.9 | 18.7 | 10.7 | | 52 | Extracted high × high | DD × DD | 1.9 | 4.0 | 3.8 | 3.2 | 3.0 | 1.7 | 4.7 | 19.7 | 35.8 | 22.2 | | 53 | Heterozygous × extracted low | DR × RR | 35.8 | 31.3 | 23.2 | 6.3 | 2.7 | 0.9 | ... | ... | ... | ... | | 54 | Extracted low × low | RR × RR | 50.0 | 50.0 | ... | ... | ... | ... | ... | ... | ... | ... | +-------+------------------------------+----------------+------+------+------+------+-----+-----+------+------+------+------+ CHAPTER VIII. CREST. In my report of 1906 I called attention to the nature of inheritance of the crest in the first and second generations. The result seemed simple enough on the assumption of imperfect dominance. However, in later generations difficulties appeared, one of which was referred to in a lecture given before the Washington Academy of Sciences in 1907. I stated (1907, p. 182), that "when a crested bird is crossed with a plain-headed one, and the crested hybrids are then crossed _inter se_, the extracted recessives of the second hybrid generation are plain-headed, to be sure, but they show a disturbance of certain feathers." This was an illustration of the statement that recessives which are supposed to come from two pure recessive gametes show in their soma traces of the dominant type. Dr. W. J. Spillman, who was present, made the suggestion that the crest is composed of two characters, _T_ and _t_, instead of a simple element, and that when _t_ alone is present the result will be the roughened _short_ feathers on top of the head.