| SUMMARY. | +---------------------------------------+--------------------------------------------------------------------------- | | Grades of boot in offspring, reduced to percentages. | | Crosses. +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--------+ | | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |Average.| +---------------------------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--------+ |Cochin | 5.4| 1.8| 5.4| 28.0| 24.3| 21.6| 9.0| 2.7| 0.0| 1.8| ..| 3.91 | |Brahma | 7.8| 13.8| 16.8| 31.0| 17.5| 7.8| 3.4| 1.1| 0.7| ..| ..| 2.84 | |Silkie | 67.6| 13.5| 5.4| 5.4| 5.4| 2.7| ..| ..| ..| ..| ..| 0.76 | +---------------------------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--------+ An inspection of Table 33, which gives the distribution of grades of boot in the offspring constituting the first hybrid generation, might well lead to the conclusion that inheritance is here of a blending nature, or that, if either condition is dominant, it is the booted one, as suggested in my report of 1906. On this hypothesis the offspring with no boot illustrate imperfection of dominance, and one would say that, in booting, dominance is very imperfect. However plausible such an interpretation might appear when based on the first hybrid generation alone, it becomes untenable when subsequent generations are taken into account, as we shall see later. The hypothesis breaks down completely in the second hybrid generation and we are forced to the opposite hypothesis, namely, that the clean-shanked condition is dominant. Such an hypothesis would seem, at first, to contravene the principle enunciated in my report of 1906 that the more progressive condition is dominant over the less progressive condition, or absence. But such is not necessarily the fact. We have no right to assume that presence of boot is the new character. The rest of the body of poultry (save the head) is covered with feathers. If the foot is not it must be because there is something in the skin of the foot that inhibits the development of feathers there. And this inhibiting factor is dominant over its absence. Table 33 shows that the Silkie crosses yield an exceptionally high per cent of the dominant clear-footed condition. This is additional evidence that the Silkies are DR, and so this cross produces 50 per cent of pure extracted dominants in addition to 50 per cent of heterozygotes in booting.