252 THE AMERICAN NATURALIST [Vol. LVI 



lumbian) fowls and buffs— in which to be sure there is 

 some variation in the amount of black pigment present 

 in certain parts of the body, but apparently no epistatic 

 pattern factors are introduced from either side of the 

 cross to obscure the visible segregation of the main fac- 

 tors. Eestrietion of buff as found in Columbian fowls 

 is, therefore, a valuable sex-linked gene for use in meas- 

 uring linkage or in other Mendelian experiments with 

 poultry while buff appears to be the best color variety 

 to be used in studying the inheritance of unknown plu- 

 mage characters. The Brown Leghorn or game type plu- 

 mage pattern, although it resembles the supposed wild 

 type form, is in the writer's opinion less valuable than 

 buff because of the often evidenced^ presence in the ge- 

 netic constitution of the Brown Leghorn of epistatic pat- 

 tern factors for extension of black pigment, stippling, etc. 



The general results of the experiments reported have 

 been to confirm and extend the previously known facts 

 regarding the inheritance of the Columbian variation. 

 The genetic relationships of this pattern and the buff 

 coloration also throw some interesting light on the evo- 

 lution of these two color varieties. They differ, it has 

 been shown, only in one main gene which determines the 

 production or restriction of buff in the plumage. Both 

 are able to develop black pigment in certain parts of 

 the plumage, while they differ quantitatively in the de- 

 gree to which black may be produced. The former single 

 factor difference probably arose as a single mutation, 

 while the latter and less important difference is one which 

 could be brought about by selection of small variations 

 which had already arisen in a common parental stock. 



The variation which produced the chief difference be- 

 tween these two color varieties, i.e., the restriction of 

 buff, undoubtedly took place at least 75 years ago and 

 probably in China, although there is no evidence that the 

 same variation has not occurred several times. The first 

 known Columbian breed was probably the Gray Shang- 



8 Sturtevant, A. H. (1912); Lefcvre, G. (1916). 



