Simpson: Coat-Pattern in Mammals 



337 



RINGMASTER, A GOOD TYPE OF ROAN SHORTHORN 



The usual location of the belt in this breed is indicated. Neither the roan color nor the belt 

 pattern can be heritably fixed, being the result, Mr. vSimpson thinks, of a single white 

 factor and a single red factor paired in the primordial ^-exual cell or zygote formed by 

 the union of sperm and ovum. Roans are produced in 100% when all-red and all-white 

 animals are mated; but when roans are mated together, only half of the produce are 

 roans. In other words, the pattern is strictly heterozygous, according to the experience 

 of breeders, but it can be created anew whenever it is desired, by the mating of pure white 

 and pure red individuals to produce the required heterozygous pattern-determiner. (Fig. 6.) 



equal and semi-dominant elements: one 

 for making all white, the other for 

 making all color; and these two factors 

 are proved by breeding test to lie in the 

 same chromosome pair. Thus when 

 heterozygous, they create a spotted 

 animal; when the white is doubled 

 (homozygous), the individual must be 

 all-white; when the color-chromosome 

 is doubled the animal is selfed, and may 

 be either bay, brown, chestnut, or black, 

 according to its inheritance. The Mende- 

 lian ratio from a spotted mating is 

 1:2:1, white, spotted, colored: the same 

 as the ratio from conjugating roan 

 Shorthorns. Both the white and the 

 self from spotted matings have proved, 

 in my observation, pure and homozy- 

 gous. The spotted Shetland acts like 

 the spotting of pure Holstein cattle, and 

 does not segregate. A peculiarity of 

 the selfs from spotted matings is the 

 absence of the usual white points, in- 

 dicating that this selfing factor is 

 different from the ordinarv factor that 



produces standard colors in horses, 

 most of which bear white markings on 

 feet, legs or face. 



Dr. Frank R. Lillie referring to Hol- 

 steins, of which for a number of years 

 he has maintained an extensive herd of 

 pure-breds, tells me: — "I believe that 

 it is possible to breed for white or black, 

 but results are surprising. One of our 

 bulls (very white himself and of whitish 

 ancestry) certainly puts more white on 

 his calves from the same cows than the 

 darker bulls. A pure black Holstein is 

 an impossibility, I believe; if there is any 

 black below the knees you can be sure 

 of mongrel blood. The nearest we 

 have come to pure white is in the case 

 of a young heifer with a black tip to one 

 ear and a black spot the size of a half- 

 dollar on the neck. I think it would be 

 possible to soon breed the black out." 



Among the freaks of factor combina- 

 tions which I have seen, was a percent, 

 of striped-roan pigs, the produce of the 

 second Schwarzwald-wild top on white 



