least_ 25 per cent of the offspring should be recessive and probably a much larger proportion. The results in table 34 are absolutely incompatible with this hypothesis, since, in one case, there are only 2 per cent that can not develop boot. Two extracted clean-footed birds sometimes throw boot and sometimes not, and this result is to be expected on the hypothesis that clean-footedness is dominant, but two heavily booted birds can not transmit the boot inhibitor. TABLE 34.--_Distribution of boot-grade in the F2 generation of booted × non-booted poultry._ +------------------------------------------------------------------------------------------------------------------+ | COCHIN CROSSES. | +---+---------------------------------------+-------------------------------------+--------------------------------+ | | Mother. | Father. | Offspring. | +---+---+-----+-----------------------------+---+----+---------------------+------+--------+-------+-------+-------+ |Pen|No.| Gen.| Races. | Grade.|No.|Gen.| Races. |Grade.| Boot | Boot | Boot | P. ct.| |No.| | | | | | | | |present.|slight.|absent.|absent.| +---+---+-----+---------------------+-------+---+----+-----+---------------+------+--------+-------+-------+-------+ |650|170| F1 |Bl. Coch. × Wh. Legh.| Pr. |265| F1 |Bl. Coch. × Wh. Legh.| Pr. | 19 | 2 | 2 | 8.7 | |650|263| F1 | Do. | Pr. |265| F1 | Do. | Pr. | 36 | 2 | 2 | 5.0 | |650|278| F1 | Do. | Pr. |265| F1 | Do. | Pr. | 26 | 4 | 4 | 11.8 | |650|361| F1 | Do. | Pr. |265| F1 | Do. | Pr. | 24 | 2 | 9 | 25.7 | |650|364| F1 | Do. | Pr. |265| F1 | Do. | Pr. | 39 | 5 | 3 | 6.4 | | | | | +--------+-------+-------+-------+ | | | | Totals (179) | 144 | 15 | 20 | 11.1 | | | | | | | | | | | | | | |========|=======|=======|=======| |654|602| F1 |Wh. Legh. × Bf. Coch.| Pr. |704| F1 |Wh. Legh. × Bf. Coch.| Pr. | 11 | 4 | 5 | 25.0 | |654|828| F1 | Do. | Pr. |704| F1 | Do. | Pr. | 7 | 11 | 0 | 0.0 | |654|640| F1 | Do. | Pr. |704| F1 | Do. | Pr. | 13 | 2 | 3 | 16.7 |