CATARACT. 105 



being all reconcileable on the ground of the dependence for magni- 

 tude on the degree of contraction of the pupil ; and for colour, on 

 the circumstance of its being the lens itself that we behold, or the 

 vitreous humour, or other parts changed in colour, through it re- 

 maining unchanged ; the latter being that state of eye to which the 

 appellation of glaucoma has been given. 



The CATARACTOUS Change is a general, not a partial one. We 

 do not, in the cataract arising from periodic ophthalmia, perceive 

 any distinct and separate nucleus or focal point of opacit}^; but we 

 discover commonly a general cloudiness pervading the entire lens, 

 and this speedily resolves itself into streaks of white or nebula 

 running from the circumference in radii towards the centre. There is 

 a species of cataract which begins in a small white speck, no larger 

 at first than a pin's point, in the very heart of the lenticular body; but 

 this is not, I believe, to be regarded as the offspring of periodic 

 ophthalmia, although I have known the latter disease attack an 

 eye in which such a cataract already existed. 



In October 1841, a black mare, three years old, was recruited for the First 

 Life Guards, having in her off eye a cataract, consisting in a white speck of 

 the magnitude of a millet seed, in the very centre of the lens, and which was 

 by no means easy of discernment, save to any one accustomed to examine 

 eyes. The dealer, an acute observer in his way, declared he had not been 

 able to detect it until the mode of doing so was pointed out to him. My 

 opinion was, that it was a cataract of a kind which had no connexion with 

 periodic ophthalmia, and that it might remain, for years even, in statu quo. 

 On the 22d of April following — six months afterwards — she was brought to 

 me with ophthalmia in the cataractous eye ; of which she was discharged 

 "cured" on the 8th of May. Again she returned, however, on the 18th of 

 June, with another attack ; and again left the infirmary ; but now, with her 

 eye changed in aspect, lustreless, obscured, contracted in pupil, and intolerant 

 of light : evidently, in fact, breeding cataract, in which state it will probably 

 continue until it shall experience another relapse. 



A Spontaneous Cataract I believe this to be, if there be 

 any such thing in horses. Several cases like it stand on record, 

 some of which I shall introduce by way of illustration here; from 

 which we may glean that it differs essentially from the cataract of 

 ophthalmia in formation and appearance, and in the circumstance 

 of being unattended with any disease or change in other parts of 



VOL. III. P 



