46 BULLETIN 1121, U. S. DEPARTMEN?Y OF AGRICULTURE. 
TABLE 13.—The vigor of heterozygosis to be expected in various experiments with respect to 
characters determined in various degrees by the sire, dam, and the animal in question. 
Character deter- Vigor of heterozygosis, 1 in random-bred stock, 0 in ultimate inbred stock. 
mined by— 
Sire. | Dam. | Young. Be Al. A2. A3. A4, Ad. Ao. CO. 
0 0 1 1 0.750 0. 625 0. 500 0. 406 0.328 0 1. 000: 
0 4 3 1 . 812 . 656 saci . 430 .347 0 . 750 
0 4 3 1 . 875 . 687 . 562 453 . 367 0 . 500 
0 3 ‘ 1 . 938 . 719 . 594 476 . 386 0 250 
0 1 0 1 1.000 . 750 . 625 . 500 . 406 0 0 
Zz 3 0 1 1.000 . 750 | - 625 . 500 . 406 0 0 
1 0 0 1 1. 000 . 750 . 625 . 500 . 406 0 0 
Character deter- 
mined by— 
Sire. | Dam. | Young.| Cl. C2. C3. C4, C5. Coo. CA. AC. CC. 
0 0 1 0. 500 0. 500 0.375 0.312 0. 250 0} 1.000} 1.000 1.000 
0 4 3 . 625 . 500 - 406 . 328 . 261 0 .750 | 1.000 1.000 
0 4 4 . 750 - 500 . 438 . 344 . 281 0 - 500 1.000 1.000 
0 3 4 . 875 - 500 . 469 . 304 . 296 0 .250 | 1.000 1.000 
0 1 0 1.000 . 500 . 500 . 375 -ol2 0 0 1.000 1.000 
4 4 0 1.000 | . 500 . 500 soho si) 0 . 500 . 500 1.000 
1 0 0 1.000 . 500 - 500 . 375 | 312 0} 1.000 0 1.000 
if 
Note that Experiments CC with the full vigor of the original stock 
and C2 with half this vigor are constant in position regardless of the 
relative importance of sire, dam, or the young themselves. 
These theoretical conclusions are based solely on the hypothesis 
that the hereditary element in the various characters is determined 
wholly by Mendelian factors and that there is more tendency for the 
detrimental factors to be recessive than dominant. Comparison 
with the actual results (Fig. 27) shows that the agreement is as close 
as could be reasonably expected. 
Adult weight and resistance to tuberculosis are examples of char- 
acters determined wholly by the young themselves. ‘The percentage 
raised of the young born alive seems to be determined about three- 
fourths by the heredity of the young and one-fourth by the dam. In 
total percentage raised, rate of gain between birth and weaning, and 
weight at weaning, the breeding of the dam and of the young are 
about equally important. The data for birth weight indicate that 
here the breeding of the dam counts for about three-fourths, young 
only one-fourth or less. The percentage born alive depends almost 
completely on the dam. In frequency of litter, the heredity of young 
counts for nothing, but the sire seems to have twice as much influence 
as the dam. In size of litter there is complete determination by the 
dam. The young per year and young raised per year are merely 
combinations of certain of the other characters. For the last named 
there is something like one-eighth determination by the young. 
One result which seemed rather puzzling was the relatively low 
record of Experiment CG, in which the parents were selected as ex- 
