EFFECTS OF INBREEDING AND CROSSBREEDING. 1a 
crossbreeding experiment is shown in Table 3 by percentages. These 
percentages can be applied to the differences between each inbred 
family and the total inbred stock as shown in Table 2 in order to find 
the extent to which the ancestry of the various crossbreeding experi- 
ments was above or below the average. 
TaBLE 4.— The estimated superiority (+-) or inferiority (—) of the inbred ancestors of the 
crossbreds to the total inbred stock. 
| The figures are based on the percentages given in Table 2and may be compared with the actual superiority 
of the crossbreds over the inbreds as shown in that table.] 
i { | 
| | Pern | Birth | 
wena: | Per | cent | per | Birth | weight Weight} Size Litters | Young) ee 
aga | Shades of cent weight| of Gain. | at 33 of er er | Taised 
ment. born those . Pp Pp per 
raised. | (total).| those days. | litter. year. year. | 
alive. | born | aad | year. 
_ alive. ; 
Pao ae pes JES SAUTER ES 
Co: 
Sire... -| +0.6, -10  —0.8 0.0; —0.4 -0.6) -—0.5) -—0.4  -—3.3 —3.7, — 4.9 
a Dam. —0.2} —0.9/ -—1.3|] +01] 404! 403] 403] 4+04/ —20/) -—16] — 3.3 
Sire....| 40.1] —1.0] -1.0| -07] -03} 401] —01] +06] -03/ +03] —12 
es Dam.. —0.6) -—1.1|) —15 > 410) 41.9) 4+3.7| 42.9] 41.4 43.9, +5.2|) + 3.1 
Sire...) +04) -0.5) -—0.2 403 > 404 42.3) 41.5! 41.0 43.0) +4+41/ + 3.0 
= Dam. . | 0.0 -—0.8)> -—0.9)> -—15) -—12) -—2.2!) -1.8|) -—0.2 —0.3 =e HE 
- | j 
Sire...-}- +11) —1.9| —L2)} 40.9); +0.6|) 42.1] 41.5 | 40.5 —5.5) —4.9 | — 7.4 
Dam.. 40.8 -—18, —14)/ 41.0; +10) 42.6) 42.0) 41.1 —5.7, —4.6| — 7.4 
ae |} +0.8 -—16' -1.2) 40.5 | 40.3 +12) +09) +0.4 -5.0 -—46)|) — 6.7 
#11) 21) -14) 405) 01) —03| -02) -a8) 76 -83 10.5 
° 
ha 
| 
The results are shown in Table 4. It will be seen that while the 
ancestors of the crossbreds were slightly above the average in some 
respects, as in weight and percentage born alive, in other respects 
they were below the average, notably in frequency of litter and the 
characteristics which depend on it. 
In all important cases the corrections which might be made are 
small compared with the actual differences among the experiments. 
It is clear that these differences are not due to selection of superior 
inbred families in making the crosses, 
In the case of the selection experiments CG and CL, the most 
important consideration relative to ancestry is the degree to which 
they were derived from different crossbreeding experiments. This 
is shown in Table 5. 
TABLE 5.—The origin of the males and females used in experiments CL and CG, in per- 
centages. 
[Each mating weighted by the number of litters produced through 1919.] 
Ck. | CG: Cr. | CG. 
Experiment. —-—_———_ ———_,—|| Experiment. 
| Sire. | Dam. | Sire. | Dam. | Sire. | Dam. | Sire. | Dam. 
-|| 
Inbred... ....... | 52) 45] 0 Ay) | eo: eerie 27 te 164 Ly £5 | othe 
Taney“ wee } 90} 0 | 20 A OO... ... cc. fer WT fo 16.4 bee 2. 8'f 1,129 
Chen scnaorewt a = Fe - Se ee M84) Os... 17.9; 187 0 0 
) a ee 27th 0.9 [re Mee |iiol 8 Atbees ai. os G  bre-0 36.1| 228 
<2 ip aay | 2.2] 0 2a). 0 | 
