SCIENCE 



table; the expected proportions in the more 

 complex cases being given above the actual 

 findings in parenthesis. The matings were 

 made and the offspring examined in major 

 part at the New Hampshire Agricultural Ex- 

 periment Station and in minor part at the 

 Station for Experimental Evolution. The 

 latter station was able to contribute especially 

 to the results of later generations. For 

 horned females, Dorsets were used ; for horned 

 males Rambouillets, Dorsets and the Scottish 

 4-horned race. As hornless races the Downs 

 were chiefly employed. It is not our purpose 

 now to give complete details, as the experi- 

 ments are being continued and full data will 

 be deferred until the publication of our final 

 report. 



The results of the table accord very closely 

 with expectation, so that we are justified in 

 concluding that an explanation of the results 

 like that we offer is the correct one. By our 



formula, then, the case of inheritance of 

 horns in sheep is brought quite into line with 

 that of other sex-limited characters, its pecul- 

 iarities being due to an inhibitor of horn de- 

 velopment that is carried in the sex-chromo- 

 some. 



LITERATURE CITED 



Bateson, W., 1909, "Mendel's Principles of He- 

 redity," Cambridge, Eng., University Press. 



Castle, W. E., 1911, "Heredity in Belation to Evo- 

 lution and Animal Breeding," New York, Ap- 

 pleton. 



Guyer, M. F., 1910, "Accessory Chromosomes in 

 Man," Biol. Bull, XIX., 219-234, PI. I. 



Wood, T. B., 1905, "Note on the Inheritance of 

 Horns and Face Color in Sheep," Jour. Agrio. 

 Sri., I., 364, 365, PI. IV. 



T. E. ARKELL, 

 C. B. DAVENPORT 

 DURHAM, N. H., 

 COLD SPRING HARBOR, N. Y., 

 January 29, 1912 



