In hybrids of both classes the greatest number of toes occurring on one foot never exceeds the greatest number possessed by its parents; indeed, the most polydactyl hybrids of the F1 generation of Silkies never have as many as 6 toes on one foot. This result is not to be explained as due to a regression towards the 4-4-toed condition, but rather as due to the intermediate condition of the heterozygote. For 80 per cent of the hybrids show either the typical or the reduced D type on one or both feet, although neither parent exhibits these types. We have next to consider the results of mating together the F1 hybrids. Table 11 gives the results of all matings of this sort. TABLE 11.--_Frequency of the various types of toes in the second hybrid generation between normal and extra-toed races. Lettering as in table 10._ +------------------------------------------------------------------------------------------------------------------------+ | A. HOUDAN CROSSES (F1 × F1). | +------+-----+------------------------------+------------------------------+---------------------------------------------+ | | | Mother. | Father. | Offspring. | | | +-----+------------------+-----+-----+------------------+-----+----------------------------------+----------+ |Serial| Pen | | | | | | | | Average | | No. | No. | | | No. | | | No. | Types of toes. | num. of | | | | No. | Races involved. | of | No. | Races involved. | of +------+------+------+------+------+ toes per | | | | | |toes.| | |toes.| 4-4 | 4-5 | 5-5 | 4-6 | 5-6 | bird. | +------+-----+-----+------------------+-----+-----+------------------+-----+------+------+------+------+------+----------+ | 1 | 631 | 429 |Houd. × Wh. Legh. | 5-5 | 83 |Wh. Legh. × Houd. | 4-4 | 14[A]| 7 | 28 | 1 | .. | 9.3 | | 2 | 728 | 174 | Do. | 5-5 | 258 | Do. | 5-5 | 11 | 1 | 20 | .. | .. | 9.3 | | 3 | 631 | 448 | Do. | 5-5 | 409 | Do. | 4-4 | 13 | 4 | 18 | .. | .. | 9.1 | | 4 | 637 | 529 |Houd. × Min. | 5-5 | 570 |Houd. × Min. | 4-4 | 4 | .. | 5 | .. | .. | 9.1 | | 5 | 631 | 430 |Houd. × Wh. Legh. | 4-4 | 83 |Wh. Legh. × Houd. | 4-4 | 20 | 1 | 21 | .. | .. | 9.0 | | 6 | 631 | 504 |Wh. Legh. × Houd. | 5-5 | 83 | Do. | 4-4 | 27 | 3 | 23 | .. | .. | 8.9 | | 7 | 631 | 174 |Houd. × Wh. Legh. | 5-5 | 83 | Do. | 4-4 | 14 | 9 | 11 | ..