TABLE 44.--_Brahma crosses. (All entries are percentages.)_ +---------------+------+----------------------------------------------------------------------------+ | | | Boot-grade in offspring. | | Percentage. | From +------+------+-----+-----+-----+-----+-----+-----+-----+-----+-----+--------+ | |table.| | | | | | | | | | | |Average | | | | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | grade. | +---------------+------+------+------+-----+-----+-----+-----+-----+-----+-----+-----+-----+--------+ |Pure blood | 31, B| .... | .... | ....| 3.3| 3.3| 6.6| 24.6| 4.9| 9.8| 14.8| 32.8| 7.62 | |F1 (D × R) | 32 | 7.9 | 13.8 | 16.8| 31.0| 17.5| 7.8| 3.4| 1.1| 0.7| ....| ....| 2.84 | |Extracted R × R| 39 | .... | 0.3 | 0.7| 4.2| 7.7| 13.6| 10.5| 9.8| 18.5| 16.0| 18.8| 7.25 | |DR × RR | 40 | 2.3 | 2.7 | 9.8| 15.1| 16.7| 14.3| 11.9| 7.3| 8.8| 7.2| 4.0| 5.04 | | | |\---------------\/---------------/ \--------------\/-------------/| | | | | 50 p. ct. DR. 50 p. ct. RR. | | |DR × DR | 42 | 12.3 | 7.2 | 12.7| 20.9| 14.9| 12.8| 7.3| 4.4| 3.8| 2.3| 1.4| 3.59 | | | |\------\/------/ \------\/------/ \--------------\/-------------/| | | | | 25 p. ct. DD. 50 p. ct. DR. 25 p. ct. RR. | | |DR × DD | 41 | 29.5 | 21.3 | 16.4| 23.0| 8.2| 1.6| ....| ....| ....| ....| ....| 1.69 | | | |\-----\/----/|\----------\/---------/| | | | | | | | | |50 p. ct. DD.| 50 p. ct. DR. | | | | | | | +---------------+------+-------------+-----------------------+-----+-----+-----+-----+-----+--------+ If a heterozygous bird be mated to a recessive the variability of the offspring is much increased, owing to the occurrence in the progeny of both DR and RR individuals (table 40). The offspring do not, to be sure, fall into two distinct and well-defined types, as in typical Mendelian cases; but one part of the range of variation agrees fairly with that of pure RR's, _i. e._, Brahmas, and the remainder with that of heterozygotes. And if we make the division in the middle of the middle class, viz, 5, we shall find a close approximation to that equality of extracted recessives and heterozygotes that the segregation theory calls for (table 44).