574 
Journal of Agricultural Research 
Vol. xxnx, No. 7 
CONCLUSIONS WITH RESPECT TO COLOR 
The wild hog carries a single factor for the immature striping (adult 
agouti) pattern and a separate factor which intensifies that pattern. 
There is an hypostatic factor for black spotting carried by the wild or 
by the Tamworth, manifested in the cross-bred specimens from either 
breed. 
The Tamworth carries a more effective factor complex for the restric¬ 
tion of black than does the Duroc-Jersey. The factor for wild color and 
pattern is not completely dominant to the factor or factors for Tam¬ 
worth red. 
The Berkshire carries a single factor for black spotting and numerous 
independent factors for the extension of that black. Probably the Berk¬ 
shire also carries dilution or restriction factors for sandy pigment and 
some individuals carry a factor for sandy spotting. 
The Duroc-Jersey carries two factors which together produce the red 
color of that breed. Cumulatively one acts as an intensifier to the other. 
This breed lacks the factor for black spotting but possesses, probably linked 
to one of the factors for red, at least one factor and probably more for the 
restriction of black. 
The relations between the various shades of red, between the various 
shades of sandy, and between sandy and white when black is absent are 
not clear. 
There are three somatically distinct types of red “spotting/’ One is 
roaning, a second is an irregular spotting of red on a lighter ground color, 
and the third is a lighter color of belly than of sides or back. This last 
form is closely related to the agouti and striping patterns. 
Striping in domestic swine is a rather simple case of “reversion/* 
It is not expected that all of these conclusions will stand in every detail 
the test of further research. They do, however, afford hypotheses of 
color inheritance in the breeds of swine investigated and offer a working 
basis for further research by which they may be extended and revised.* 
DIFFERENCES IN GROWTH 
The economic importance of some definite knowledge in regard to fac¬ 
tors for rapid growth may be surmised from the extent of the practice 
of cross-breeding hogs in order to secure the larger size and greater vigor 
of the Fj hogs for market purposes. 
Only the Berkshire X Duroc-Jersey cross was extensive enough to 
furnish significant data upon this point. Since they were not all born 
at the same season nor even in the same year, it is obvious that they were 
not exposed to identical weather conditions nor fed rations as identical 
as would be desirable in a nutrition experiment. However, it was the 
aim always to feed the best possible ration to produce the maximum prac¬ 
ticable gains and it is believed that the data are, on the whole, reasonably 
comparable. 
The data for the variability of the Fj and F 2 generations are presented 
separately in figure i, where the curves show the coefficients of variability 
for the monthly weights for both generations from birth up to the age of 
14 months. 
6 Since this was written a report (3) of the results of a cross between mule-foot and Duroc-Jersey swine 
has been published which agrees closely with two of the main conclusions reached in this experiment, 
namely, that the presence of black as contrasted to its absence is dependent upon a single factor and that 
the different shades of red are due to the interaction of a few independent factors which do not affect black. 
The black of the mule-foot swine behaved like that of the American Hampshire as far as it has yet been 
analyzed, but whether the two are genetically identical is still undetermined. 
