+------------------------------+--------------------------------------------------------------+ | | Grades of boot in offspring, reduced to percentages. | | Races. +----+---+----+----+----+----+----+----+----+----+----+--------+ | | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |Average.| +------------------------------+----+---+----+----+----+----+----+----+----+----+----+--------+ |Cochins | .. | ..| 0.5| 1.5| 1.5| 4.0| 4.5|12.1|23.6|30.7|21.6| 8.24 | |Dark Brahmas | .. | ..| .. | 3.3| 3.3| 6.6|24.6| 4.9| 9.8|14.8|32.8| 7.62 | |Silkie |14.8|7.4|23.5|26.5|13.2| 5.9| 5.9| 2.9| .. | .. | .. | 2.72 | +------------------------------+----+---+----+----+----+----+----+----+----+----+----+--------+ [A] Determination made on embryo chicks. An inspection of table 31 shows that, in respect to booting, the Cochins and Dark Brahmas are clearly closely related to each other. Owing to smaller numbers and to other circumstances that will be discussed later, the results are less regular in the Dark Brahma offspring, but in both the range is from 2 or 3 upward to 10, with a great preponderance in grades above 5. In the Silkies, on the other hand, the greatest frequency is found in grades below 5. This difference is correlated with a difference of the parents, for the commonest grades of the parents of the Cochins are between 6 and 10, of the Dark Brahmas between 5 and 9, and of the Silkies between 1 and 3. These results suggest that the Silkie is typically heterozygous in boot, producing 25 per cent recessives (boot of grade 4-7) and 75 per cent dominant (0, 1) and heterozygous (2, 3). We shall see that this hypothesis receives support from all Silkie matings. Inside of any part of this table it appears that, on the whole, as the average grade of the boot in the progeny diminishes that of the parentage diminishes, although the correlation is by no means perfect. Thus the average of the parental grades in the first part of table 31, A (which is arranged in descending order of the averages of the offspring) is 8.5; in the lower half, 7.4. The average of parental grades in the upper half of table 31, B is 6.4; in the lower half 5.5. In table 31, C the grades are 2.9 and 2.3, respectively. This correlation indicates, without exactly measuring, heredity in grade of booting. Table 32 shows the results of crosses between Cochins (high grade of boot) and Silkies (low grade). TABLE 32.--_Distribution of boot-grades between a high and low grade of boot in parents._