EYE AS A CAMERA OBSCURA. 337 



specially attracted notice, both eyes were carefully shaded. By a liberal gift of 

 nuts, however, which occupied for a time both anterior hands, the eyes were left 

 unshaded, and could be examined. They did not exhibit the signs of extreme al- 

 binism. The pupil was not pink, and the iris was a pale blue. 



In strong contrast with the painful vision of the monkey is the quick 

 sight of a white rabbit, and several white rats and mice, which occupy neigh- 

 bouring cages. Their fur is milk-white ; the skin colourless ; the pupil pink or 

 rather crimson, and large, as compared with that of the monkey.* The ani- 

 mals were exposed freely to diffuse daylight, but did not shrink from it. No 

 conspicuous change could be observed in the pupil ; there was no oscillation of the 

 eyeballs, and no closure of the eyelids. They seemed to see as well as their non- 

 albino neighbours, and to be as little incommoded by daylight, and they were 

 equally quick in discerning and seizing food. Their keepers, who were aware 

 of the monkey's peculiarities of vision, considered the other albino animals 

 quite as sharp-sighted as their dark-eyed brethren. I would not say so much 

 myself, or rather I would say it differently. I have no doubt that the albinoes 

 would see worse in full sunlight, but I have as little doubt that they would see 

 better in faint twilight. 



It cannot then, I think, be questioned, that in those animals which exhibit 

 the full development of long hereditary albinism, the sensitiveness of the retina to 

 light has undergone a permanent abatement, whilst the iris has probably altered 

 also in thickness and contractility. I venture to predict, that if ever an albino 

 race of men shall be observed or developed, they will prove, after the lapse of 

 a generation or two from their founders, to have eyes as serviceable as those of 

 the majority of mankind.f 



* A comparison, also, of pink-eyed with dark-eyed rabbits appeared to show that in diffuse day- 

 light the average size of the pupil is the same in both ; but in direct sunlight the albino pupil is 

 smaller. 



J In truth, in the case even of casual human albinoes, vision, however painful in full daylight, is not 

 to any marked extent optically imperfect ; and in the diffuse or moderate light by which they see cor- 

 rectly, reflection of its rays within the eye is occurring as certainly as when the light is direct and intense. 

 I hesitated to urge thus much when the text of this paper was read to the Society, although the 

 conclusion in question seemed justified by the accounts on record of albinism, especially by Dr Sachs' 

 very interesting description of his own case and his sister's. [Hist. Nat. duorum Leucaethiopum auc- 

 toris ipsius et sororis ejus, a G. Sachs, M.D. See also my Researches on Colour-Blindness, p. 102). 

 But since this paper was read, I had an opportunity, through the kindness of Dr James Sidey, of test- 

 ing, along with Mr James C. Maxwell, the vision of an albino girl, aged 18 or 19. She was born in 

 India, of Scotch parents, in humble life, and is, in all respects, a well-marked case of albinism. She 

 sees with much less suffering in this country, than she did in that of her birth, but bright sunlight still 

 distresses her. There is occasional strabismus of one eye, and both eyes exhibit, under exposure to 

 light, the tremulous oscillation characteristic of albinism ; not, however, to a very great degree. She 

 thinks that her vision has improved within the last few years, but how far this is the result merely 

 of removal from the influence of a tropical sun, it would be difficult to determine. 



We found her quick and intelligent. By diffuse daylight, she distinguished the forms of objects 

 rapidly and accurately. Many trials also were made as to her perception of colours, which Mr Max- 



