320 



The Journal of Heredity- 



eleven and ten chromosomes respec- 

 tively. This being the case, it seems 

 probable that dogs represent, even in 

 spite of their slow breeding and large 

 size, the best material available among 

 the mammals for a relatively complete 

 genetic analysis. They are found in 

 more color varieties than occur in any 

 other domesticated animals. They have 

 more structural differences and a greater 

 size difference between breeds as well 

 as a greater difference in number of 

 young per litter than are found in other 

 mammals. There is apparently com- 

 plete fertility between different breeds. 

 Artificial insemination has been tried 

 (Iwanoff, 1903) and has been found 

 possible, a fact which might enable 

 experimenters to overcome any me- 

 chanical difficulties in crossing very 

 large with very small breeds. They 

 possess more clearly defined instincts, 

 characterizing various varieties than 

 do other mammals. To sum up, there- 

 fore, it may be stated that if an in- 

 vestigator is willing to wait for his 

 results, dogs provide a field unequalled 

 among mammals in the respects above 

 outlined. 



IV. SUMMARY AND CONCLUSIONS 



From a study of the breeding records 

 of Great Danes in the American Kennel 

 Club Stud Books, the following con- 

 clusions can be drawn : 



1. There is a single mendelizing 

 factorial difference between the intense 

 pigmented (black, brindle, and fawn) 

 varieties on the one hand, and the 

 dilute varieties (dilute black, dilute 

 brindle, and dilute fawn) on the other 

 hand. The factor D for intensity is 

 epistatic to its allelomorph d — the 

 factor for dilution. 



2. The three coat conditions repre- 

 sented by solid black, brindle, and 

 fawn are dependent upon three mutually 

 allelomorphic factors: E for full ex- 

 tension of black pigment, E^ for its 

 partial extension as seen in the brindling 

 pattern, and e^ for its restriction to the 

 muzzle, nose, feet, and a small area 

 near the eyes— a condition typical of 



the fawns. Black (E) animals may 

 carry either brindle (EO or fawn (e^) 

 but not both; brindles (E^) may carry 

 fawn (e^) but not black (E), and fawns 

 (e^) can carry neither brindle (E^) nor 

 black (E). 



3. Harlequin spotting (H) is epistatic 

 to solid coat color (h) and apparently 

 differs from it by a single mendelizing 

 factor. 



4. Minute white spots on the chest 

 or on the feet occur rarely among the 

 progeny of solid colored animals. Their 

 appearance is probably due to a factor 

 (s) for piebald spotting which is hy- 

 postatic to its allelomorph (S) for self 

 coat color. 



LITERATURE CITED 



Barrows, W. M., and Phillips, J. N. (1915): 



Color in Cocker Spaniels. Jour. Heredity, 



6: 387-397. 

 Castle, W. E., et al. (1909): Inheritance in 



Rabbits. Pub. Carnegie Inst, of Wash. 



No. 114, 70 pp. 4 plates. 

 Castle, W. E., and Little, C. C. (1909): 



The Peculiar Inheritance of Pink-Eyes 



among Colored Mice. Sci. N. S. 30: 



313-314. 

 DoNCASTER, L. (1905): On the Inheritance of 



Tortoise Shell and Related Colors in Cats. 



Proc. Camb. (Eng.) Phil. Soc, 13: pt. I, 



p. 35. 

 Iwanoff, E. J. (1903): Ueber kunstliche 



Be'^ruchtung von Saugetieren. Vorl. Mitt. 



Biol. Zentralbl., 23: s. 640. 

 Lang, A. (1910): Ueber Alternative Vererbung 



bei Hun den. Zeit. f. Abst. Ver., 3: 1-33. 

 Leighton, R. (1907): The New Book of the 



Dog. Cassell & Co., London, Eng. xvi-|- 



620 pp. 

 Little, C. C. (1911): The "Dilute" Forms of 



Yellow Mice. Sci. N. S., 33: 896-897. 

 Little, C. C. (1914): Inheritance of Coat 



Color in Pointer Dogs. Jour. Hered. 5: 



244-248. 

 Malone, J. Y. (1918): Spermatogenesis in the 



Dog. Trans. Amer. Micr. Soc, 37: 97- 



100. 2 plates. 

 Pearson, K., Nettleship, E., and Usher, 



C. H. (1913): A Monograph on Albinism in 



Man, Part II, 460-512. 

 "Stonhenge" (Walsh, T. H.) (1873): The 



Dog. Lee and Shepard, viii-f 470 pp. 

 Whiting, P. W. (1918): Inheritance of Coat- 

 Color in Cats. Jour. Exp. Zool., 25: 539- 



569. 2 plates. 

 Wright, S. (1918): Color Inheritance in 



Mammals. The Dog. Jour. Heredity, 9: 



87-90. 



