We are now in a position to consider the effect of back crosses (table 36). The contrast between the totals in tables 36 and 37 is very great. The strict Mendelian expectation is: in the DR × D crosses 50 per cent DD (clean-footed) and 50 per cent heterozygous, which, with imperfect dominance, might be expected to show foot-feathering. Actually about 46 per cent are clean-footed. In the DR × R crosses expectation is that 50 per cent certainly (the extracted recessives) and 50 per cent more possibly will have the shanks feathered, on account of imperfect dominance of the heterozygotes. Actually all have feathered feet. These statistics thus confirm the view of the dominance of the inhibiting factor. Were clean shank recessive, then the DR × R crosses must give 50 per cent clean-footed and probably over. The actual result, none clean-footed, is not in accord with the latter assumption. TABLE 36.--_Distribution of boot-grade in DR × D (non-booted) crosses._ +---+-----------------------------------------+---------------------------+--------------------------------------+ | | Mother. | Father. | Boot-grade in offspring. | | +---+-----+----------------------+--------+---+----+---------+--------+---------+--------+--------+----------+ |Pen| | | | | | | | | | | | | |No.|No.| Gen.| Races. | Grade. |No.|Gen.| Race. | Grade. | Present.| Slight.| Absent.| Per cent.| | | | | | | | | | | | | | present. | +---+---+-----+----------------------+--------+---+----+---------+--------+---------+--------+--------+----------+ |653|508| F1 | Wh. Legh. × Bf. Coch.| Pr. |117| P. | Game. | 0 | 3 | 4 | 6 | 46.2 | |653|508| F1 | Do. | Pr. |116| P. | Do. | 0 | 6 | 5 | 4 | 26.7 | |653|577| F1 | R × Bf. Coch. | 3 |117| P. | Do. | 0 | 1 | 0 | 7 | 87.5 | |653|577| F1 | Do. | 3 |116| P. | Do. | 0 | 1 | 3 | 2 | 33.3 | |653|587| F1 | Do. | 1 |117| P. | Do. | 0 | 1 | 2 | 4 | 57.1 | |653|587| F1 | Do. | 1 |116| P. | Do. | 0 | 3 | 3 | 2 | 25.0 | |653|635| F1 | Do. | 3 |117| P. | Do. | 0 | .. | 1 | 6 | 85.7 | |653|635| F1 | Do. | 3 |116| P. | Do. | 0 | 2 | 2 | 1 | 20.0 | |653|652| F1 | Do. | 5 |117| P. | Do. | 0 | 5 | 8 | 4 | 23.5 | |653|652| F1 | Do. | 5 |116| P. | Do.