AND COLOUR OF THE IRIS. 277 



Albinos, is combined an entire deficiency * of colouring 

 matter in the eye ; so that tlie iris and choroid have a more 

 or less red hue with a tendency to violet, from the colour of 

 the blood in tlieir numerous capillaries. Different children 

 of the same family not unfrequently have opposite complex- 

 ions, where one of the parents is fair and the other dark : 

 hence we may see brothers and sisters with different co- 

 loured irides. 



Those animals only, in which the skin and hair are sub- 

 ject to variety of colour, vary in that of the eyes. This is 

 not confined, as the ancients thought, to man and the horse, 

 but extends also to others, particularly of the domesticated 

 kinds. Moreover, the iris sometimes exhibits more than 

 one colour in those animals which have a spotted skin ; as 

 was noticed by Molinelli f in dogs. Something of the 

 same kind may be observed in sheep and horses -, but Blu- 

 MENBACH says that it is most conspicuous in the rabbit ; 

 the gray, or those which retain the native colour of their 

 wild state, have brown irides ; those spotted with black and 

 white have the irides evidently variegated ; and the white, 

 like other leucc-ethlopic animals, have them, as is well 

 known, of a pale rose colour. 



The three principal colours of the human eye were well 

 laid down by Aristotle, viz. blue, passing in its lighter 

 tints to what we call gray ; an obscure orange, which he 

 calls the colour of the eye in the goat (F\\ yeux de chevre), 

 a kind of middle tint between blue and orange, and some- 

 times remarkably green in men with very red hair and 

 freckled skin ; and lastly, brown in various shades, forming 

 in proportion to its depth what we call hazel, dark, or 

 black eyes. The red eyes of the leuciethiopic constitution 

 may constitute a fourth division. 



♦ In his " Observations on the Pigmentum of the Eye,'' Mr. Hunter speaks 

 of the white pigmentum of the Albino, white rabbit, white mouse, ferret, &c. 

 Obs. on the Animal Economy. It seems to me easily demonstrable, that there 

 is no colouring matter in these cases ; and that the light rose colour of the iris, 

 and the deeper violet red of the pupil, depend solely on the blood. 



+ Comment. Instil. Bonnon. t. iii. p. 2S1. 



