COLOR INHERITANCE IN MAMMALS 



X., The Cat — Curious Association of Deafness with Blue-eyed White Color and 



of Femaleness with Tortoise-shelled Color, Long Known — Variations 



of Tiger Pattern Present Interesting Features. 



Sewall Wright 

 Bureau of Animal Industry, Washington, D. C. 



Tabby cat with tiger-pattern vSIAEXb 



lai 



la2 V,v V — white (normal or blue 

 eyes) 

 S,s s- — piebald (unit factor un- 



certain) 

 las I,i i — dilute tabby (maltese 



and cream) 

 lb ■ — ■ imperfect albinism of 



Siamese cat? 

 2a 1 A,a a — black 

 2a2 E,e Ee — tortoiseshell female 



ee or e orange (male or 



female) 



2a3 



2b 



3 Xa, Xb, Xc, 



Xa — finely lined or uni- 

 form tabby 

 Xe — wide striped or blotch- 

 ed tabby 

 Classification explained in paper on the 

 mouse, Journal of Heredity, 8:373 

 August, 1917. 



TWO remarkable peculiarities, as- 

 sociated with color in cats, have 

 been known for a long time. 

 Darwin^ mentions the fact that 

 blue-eyed white cats are generally deaf, 

 and also that tortoiseshells are nearly 

 always female. 



Investigations on the blue-eyed white 

 cats have been made by Przibram^ and 

 by Whiting.^ The latter has not yet 

 published his results, but has very 

 kindly permitted some mention of them 

 here. Wholly white cats may have 

 the yellow eyes of ordinary colored 

 cats, or they may have blue eyes, or 

 one eye may be yellow and one blue. 

 Whiting finds that solid white, what- 

 ever the color of the eyes, is due to 

 a unit dominant factor. Przibram 

 crossed together white cats with vari- 

 ous eye-colors. The data are not ex- 

 tensive enough to base final conclu- 

 sions on them, but there seems to be 

 inheritance of the eye color. There 

 w^as some indication that as\TTimetry 



ran in families, but not a specific kind 

 of asymmetry. The variations in eye- 

 color can best be looked upon as anal- 

 agous to the variations in extent and 

 symmetry of the white pattern in the 

 coat of any piebald mammal. As}Tn- 

 metry in such patterns has never been 

 demonstrated to have a heredity basis. 

 A tendency for as^Tumetrical eyes to 

 run in families in cats could be ex- 

 plained as due to heredity of a general 

 level in amount of color, independent 

 of the main factor for solid white. 

 Some families are at such a high level 

 that the white pattern seldom invades 

 the eyes, which therefore remain yellow. 

 Others are at so low a level that all indi- 

 viduals are blue-eyed. In families at 

 an intermediate level, it is largely 

 chance whether or not an eye is in- 

 vaded by the white, and asymmetry is 

 common. When the pattern is suffi- 

 ciently extensive to invade the eyes, it 

 is easy to understand that it might also 

 invade the inner ear, but why this 

 should cause deafness is not so clear. 

 The allied case of deafness in wall- 

 eyed white dogs has been noted in the 

 previous paper. The preceding dis- 

 cussion interprets the solid white con- 

 dition as an extreme form of a piebald 

 pattern, and not at all comparable with 

 albinism. 



White patterns, resembling the usual 

 piebald patterns of other mammals, are 

 very common in cats. No doubt the 

 factor or factors, which are responsible, 

 are independent of the other color- 

 factors, as spots of all colors can appear 

 on a white ground. The mode of 

 inheritance does not seem to have been 

 worked out. 



DILUTE COLORS IN CATS 



The dilute color of the maltese cat, 

 as compared with the black variety, 

 has been demonstrated to be due to a 

 simple recessive factor by Doncaster.^ 



139 



