140 GENETICS AND EUGENICS 



more specialized form of the dominant spotting (harlequin) 

 is found in the coach-dog (Fig. 110). Besides the five unit- 

 character variations of Great Danes, several other unit- 

 character variations can be recognized in other breeds. (See 

 Table 16.) The cranial characters of dogs show their an- 

 cestors to have been wolf -like. 



Most wolves have a protectively colored gray coat, in 

 which black and yellow pigments are intermingled on the 

 same hair somewhat as in the agouti pattern of rodents. 

 This pattern is wanting in most dogs, but has been retained 

 in some examples of the Eskimo-dog or "husky." It is 

 probably due to a dominant factor. 



A more conspicuous pattern is seen in black-and-tan dogs. 

 In a black-and-tan the general body-color is yellow (tan) but 

 with a blanket of black extending down from the back over 

 the sides of the body and the outer surfaces of the legs. A 

 yellow spot is found also above each eye. Fox hounds and 

 beagles have this pattern regularly. Airedale terriers are 

 distinguished chiefly by this pattern from Irish terriers. 

 Some setters and pointers have it while others do not. Al- 

 though the white spotting in these breeds often obscures it, 

 the black-and-tan pattern can readily be recognized in the 

 light spot above the eye. It is apparently a recessive pattern 

 factor in various breeds of dogs. Since the pattern seen in 

 black-and-tan dogs may be transferred in crosses as a unit- 

 character to dogs which are brown or red pigmented, it is 

 probably better to adopt for it a term appropriate in different 

 combinations. Bi-color has been suggested by Barrows and 

 Phillips as such a term. Bi-color black dogs are "black-and- 

 tan," bi-color brown dogs are "liver-and-tan," and bi-color 

 red dogs are "red-and-lemon." Self black breeds of dogs 

 have probably originated by a loss of an original pattern 

 factor such as the bi-color factor; and self yellow ( or red) 

 breeds by independent loss (sudden or gradual) of black from 

 the coat. Brown ("liver") varieties have originated by a 

 unit-character variation from black to brown, comparable 

 with that of various rodents. Self white occurs in dogs 



