THE SABLE VAKIETIES OF MICE 



DR. L. C. DUNN 



The variations in darkness of certain forms of fancy 

 mice have called forth different interpretations from the 

 various investigators who have studied them. The pres- 

 ent report is intended as a contribution of experimental 

 data, treating these differences as graded variations. 



The varieties of mice most commonly exhibiting dif- 

 ferences in darkness comprise those races known as 

 sables. Such mice are distinguished by a yellow belly 

 and a back of some shade of black or brown with which 

 yellow may or may not be mixed. They were first re- 

 ported by Bateson in 1903 but Miss Durham (1911) was 

 the first to breed them experimentally and to catalog the 

 variations within the sable race. Little (1913) classed 

 sables as yellows with varying amounts of dark pigment 

 in the hairs on their dorsal and lateral surfaces. Dunn 

 (1916) offered the explanation that all sable varieties dif- 

 fered from ordinary yellow by a factor or factors deter- 

 mining the quantitative increase of dark pigments, so 

 that sables formed a continuous series of increasing dark 

 dorsal pigmentation from clear yellow to black-and-tan 

 in which the back was intense black while the yellow pig- 

 mentation wa s exhibited only on the belly. Onslow ( 1917 ) 

 was "led to look upon sable as a pattern factor which 

 could give a yellow belly to a mouse of any color," but he 

 did not publish the experimental evidence upon which 

 his conclusions were based. He criticized Dunn for 

 further involving the nomenclature of the sables through 

 the use of the names "black-and-tan, " "brown and tan," 

 "black sables," and "brown sables," to designate the 

 members of the sable series. 



The use of the above term is, I believe, justified because 

 black-and-tan is recognized by the English fanciers as dis- 

 tinctly different from ordinary sable, and because none 

 of the sables described by Miss Durham behaved as did 

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