38 



The Journal of Heredity 



white of Yorkshire but also hght yel- 

 lowish reds and red roan. 



The relation of the wild color to the 

 tame colors is not certain. The wild 

 color may be looked upon, cither as 

 corresponding^ most closely to a yellow 

 like a light Tamworth, modified by the 

 addition of dark pigment, as in sable 

 mice, or to a self black such as an Essex 

 modified by an agouti factor. Simpson^^ 

 seems to incline toward the view that, 

 among the tame colors, the Tamworth 

 red is the closest genetically to the wild 

 type. As pointing the other way, how- 

 ever, may be taken his report of black 

 swine Cjl Berkshire, H Poland-China) 

 with well-defined sandy stripes like the 

 wild. Spillman^^ also speaks of the fre- 

 quent occurrence of a reddish tinge near 

 the tip of the hair of Berkshires as sug- 

 gesting the wild pattern. This view — 

 that the wild boar has an extension 

 factor — is also most in line with results 

 in other mammals and is, therefore, per- 

 haps slightly preferable as a provisional 

 hypothesis. 



As regards genetic evidence. Spill- 

 man ^^ records crosses which show clearly 

 a main unit difterence with Tamworth 

 as well as lesser differences. The wild 

 pattern was dominant in Fi, while wild 

 and red segregated clearly in a back- 

 cross with Tamworth. Reds also ap- 

 peared in F2 while some of the dark 

 colored hogs were striped, others un- 

 striped. Probably but not certainly the 

 main difference involved is in the exten- 

 sion series while perhaps an agouti 

 factor from the wild (2ai) or a density 

 factor for black from the tame (class 

 las) or both complicate the matter. 

 Frohlich'" reports on crosses of a Cau- 



casian wild sow with white Edelschwein, 

 Fi was pure white and F2 showed clear 

 segregation into 6 white to 2 black. A 

 cross with a common white boar pro- 

 duced 4 white, 3 gray and white spotted, 

 a result which can be interpreted in 

 several ways. This evidence, on the 

 whole, indicates segregation in the exten- 

 sion series rather than in intensity of red. 



One other color is known in the blue 

 roan of the Sapphire, which is being 

 developed by G. C. Griffith. According 

 toMcLean,-" most of the common breeds 

 were used in the foundation stock. The 

 color seems to have been developed by 

 selection from a white showing a trace 

 of the blue roan. This indicates that 

 the restriction factor is present. If this 

 is true, the blue would be like a sooty 

 yellow genetically, except for dilution of 

 yellow to white. 



In concluding this summary, it is 

 clear that color inheritance in hogs is a 

 subject on which much is yet to be done. 

 Nevertheless, the main facts seem to 

 point quite definitely to three indepen- 

 dent kinds of variations as responsible 

 for most colors ; first, black extension (no 

 black — small black spots — black except 

 for irregular splotches — solid black). 

 Second, variations of intensity which 

 determines whether the ground color 

 shall be white, sandy or red. A third 

 independent kind of variation is clearly 

 present in the white belted swine, in 

 ^^•hich there is a white which can ap- 

 pear on either a black or red. Further 

 investigation is needed in all three of 

 these groups to determine whether the 

 important variations fall into series of 

 multiple allelomorphs or are due to 

 independent factors. 



Sex Ratio in Cattle 

 Statistics previously published by the 

 Maine experiment station appeared to 

 indicate that there was some connec- 

 tion between the time when a cow was 

 bred (relative to the beginning of the 

 heat) and the sex of the offspring. A 

 larger series of cases has since been 

 collected, and studied from this pf)int 

 of view. In Bulletin 261 it is noted that 



Cannot Be Controlled 



"the apparent relation between these 

 two factors, which is believed by many 

 breeders to exist and which our earlier 

 statistics appeared to indicate, seems 

 now to be purely accidental." "There 

 is not now known an\- method by which 

 the sex ratio or i)r{)])ortion of the sexes 

 in cattle may be effectively controlled 

 bv the breeder." 



••Simpson, O. I. 1907. 5«., 25:426. 

 "Spillman, W. T. 1007. 5a., 25:313. 

 »8Si)il!nian, \V. 1. l'n)6. Loc. cit. 

 "Frohlich. (i. 1913. Loc. cit. 

 "McLean, I. A. 1914. Jour. Hkr.. 5:301-304. 



