24 BULLETIN 1121, U. S. DEPARTMENT OF AGRICULTURE. 
ADULT WEIGHT. 
The complete growth curve has been studied in those animals which 
have been saved beyond 33 days. The details will not be discussed 
in the present paper. It may be said, however, that a pronounced 
effect of crossbreeding is observable in the first generation of crossing 
and that about half of the increase is lost in the first generation of 
renewed inbreeding. 
Table 8 shows the average weights of males and females in the five 
large inbred families and in the random-bred stock, 1916 to 1919 
inclusive, taken at the time of recording a litter at the ages of 12 or 13 
months. The females are thus not pregnant. 
TaBLE 8.—Average weights at 12 or 13 months (1916-1919); taken after birth of litter, 
inbreeding experiments and random-bred stocks. 
Males. Females. 
Family. =e | 
Num-| Weight Num-'| Weight 
ber. (grams). | ber. | (grams). 
2. . Sots Se alee soo iccr eset ber cece ce eRe etek teed 36 | 716+ 6.9 | 35 625+ 5.3 
DSL poe osha ae Sinwiers Sie 2:6 otuin brale tao ae eich eet Brcinie 31} 845+ 9.2 33 686+11.1 
BAe Se eee, eet, SOE reat Ae eee ae ea fro Pa i Sregehe fe. eee 20 | 700+10.1 21; 6494+ 7.8 
Boseee ee Seismiceee bd chepoimteralapoy Sle. Svacd roa rare Brora cottons aremintaraiorste eaicin ee SNS 32 | 770+10.4 32) 669+ 8.6 
Bae eee oes Meee ear eictthe es gaicic ine = seco ee Res See ee ee 16 | 757+17.0 14 = 653419.1 
Totalanbredeecs ss ease eta eee bo das sae dates 135 | 761+ 5.4 135 6574 4.5 
Bee once ee eeee eae Seacoast eta ae oe RN See 58 | 852+ 9.9 60 | 700+ 7.9 
The superiority of the males over the females, of the crossbreds 
over the inbreds, and the differentiation among the inbred families, 
are brought out. | 
In Table 9 animals from the first cross between inbred families, 
and from the first generation of renewed inbreeding, are compared 
with the inbreds used in crossbreeding experiments. As in Table 
8, the weights were taken at 12 or 13 months of age after the birth 
of a litter. These inbreds are not included in Table 8. 
TABLE 9.—Average weights at 12 or 18 months (1917-1920); taken after birth of litter. 
Animals used in crossbreeding experiments. 
Males. Females. 
Experiment. : 
Num-| Weight | Num-| Weight 
ber. (grams). ber. (grams). 
Tarbpredsi Grin OF ACC Anes s Ste Pre pate eine erate ee oe eer eee 95 | 776 + 6.4 91 | 641 + 4,8 
CO G@mOC 2Ol, CAC ENO yak occ a aE Ale Seca are cian Ae es 77 | 865 + 8.8 82 | 726 + 6.6 
Cl CIM © 2) coc. sepotececnante on oeenae once sere Diee net ate Ser sees 9 | 824 +13.2 9] 667 417.5 
