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THE AMERICAN NATURALIST [Vol. XLIX 



tween black-and-tan and black, or between black-and-tan 

 and gray, or even that black-and-tan itself might be dis- 

 placed to such an intermediate condition by selection of 

 its fluctuations % Here are fruitful fields of inquiry to be 

 cultivated before we conclude with the exponents of " ex- 

 act" heredity that selection of fluctuations is useless and 

 that only mutations count in evolution. 



December 26, 1914. 



PAPERS CITED 



Castle, W. E. 



1905. Heredity of Coat Characters in Guinea-pigs and Eabbits. Publ. 

 No. 23, Carnegie Institution of Washington. 



1914. Some New Varieties of Eats and Guinea-pigs and their Rela- 

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Castle, W. E., and J. C. Phillips. 



1914. Piebald Rats and Selection. Publ. No. 195, Carnegie Institu- 

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Cuenot, L. 



1904. L'heredite de la pigmentation, chez les souris (3me Note). 



Arch, de Zool. Exper. et gen., Notes et Rev., p. xlv. 

 1909. Reeherches sur 1 'hybridation. Proc. Seventh Internal. Zool. 



Congress, pp. 45-56. (Prize essay submitted to the Congress, 



Detlefsen, J. A. 



1914. Publ. No. 205, Carnegie Institution of Washington. 

 Doncaster, L. 



1905. On the Inheritance of Coat-color in Rats. Proc. Camb. Phil. 



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Haecker, V. 



1912. Ueber Kreuzungsversuche mit Himalaya und Blaek-and-Tan 

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Little, C. C. 



1914. "Dominant" and " Recessive " Spotting in Mice. Amer. Nat., 

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 MacCurdy, H., and W. E. Castle. 



Coat-pigments and Coat-patterns in Rats and Guinea-pigs. 

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1912. Inheritance of Coat-color in Rabbits. Journ. of Genetics, 2, 



