322 



LAWS OF VARIATION. 



Chap. XXV. 



I 



" has at the same time met with defective development of 

 " the dental system." Certain forms of blindness seem to be 

 associated with the colour of the hair ; a man with black 

 hair and a woman with light-coloured hair, both of sound 

 constitution, married and had nine children, all cf whom 

 were born blind ; of these children, five " with dark hair 

 " and brown iris were afflicted with amaurosis ; the four 

 " others, with light-coloured hair and blue iris, had amaurosis 

 " and cataract conjoined." Several cases could be given, 

 showing that some relation exists between various affections 

 of the eyes and ears ; thus Liebreich states that out of 241 

 deaf-mutes in Berlin, no less than fourteen suffered from the 

 rare disease called pigmentary retinitis. Mr. White Cowper 

 and Dr. Earle have remarked that inability to distinguish 

 different colours, or colour-blindness, " is often associated 

 " with a corresponding inability to distinguish musical 

 " sounds." 23 



Here is a more curious case : white cats, if they have blue 

 eyes, are almost always deaf. I formerly thought that the 

 rule was invariable, but I have heard of a few authentic ex- 

 ceptions. The first two notices were published in 1829, and 

 relate to English and Persian cats : of the latter, the Eev. "W. 

 T. Bree possessed a female, and he states, " that of the offspring 

 " produced at one and the same birth, such as, like the mother, 

 " were entirely white (with blue eyes) were, like her, invari- 

 " ably deaf ; while those that had the least speck of colour on 

 " their fur, as invariably possessed the usual faculty of 

 " hearing." 2i The Rev. W. Darwin Fox informs me that he 

 has seen more than a dozen instances of this correlation in 

 English, Persian, and Danish cats ; but he adds " that, if one 



23 These statements are taken 

 from Mr. Sedgwick, in the ' Medico- 

 Chirurg. Review,' July, 1861, p. 

 198 ; April, 1863, pp. 455 and 458. 

 Liebreich is quoted by Professor 

 Devay, in his ' Manages Consan- 

 guins,' 1862,p. 116. 



" Loudon's ' Mag. of Nat, Hist.,' 

 vol. i., 1829, pp. 6<i, 178. See also 

 Dr. P. Lucas, ' L'Hered. Nat.,' torn. i. 

 \>. 428, on the inheritance of deafness 



in cats. Mr. Lawson Tait states 

 ('Nature,' 1873, p. 323) that only 

 male cats are thus affected ; but this 

 must be a hasty generalisation. The 

 first case recorded in England by Mr. 

 Bree related to a female, and Mr. 

 Fox informs me that he has bred 

 kittens from a white female with 

 blue eyes, which was completely deaf; 

 he has also observed other females in 

 the same condition. 



