MELANOSIS. 147 



exception to this general law : the cornea, the choroid coat, the 

 retina, the anterior and posterior chambers, the crystalline lens 

 and its capsule, have all, at one time or another, been the seat of 

 ossification ; and in almost all these cases we shall find that the 

 forerunner of the ossific change has been periodic ophthalmia. In 

 horses who have experienced attacks of this disease, inordinate in 

 violence or duration, or in number, and who have many years sur- 

 vived the termination of them in total blindness, and consequent 

 atrophy of the blind eye or eyes, we may search for, and expect 

 to find, specimens, of some kind or another, of ossification. 



Mr. Swarrick, V.S., Skipton, Yorkshire, in examining the eyes 

 of a blind mare who had died from rupture of the posterior aorta, 

 found the crystalline lens of the near eye of a cartilaginous texture, 

 and not adherent to its capsule. And of the off eye, though the 

 anterior chamber was full of aqueous humour, the posterior cham- 

 ber was " filled with an osseous deposit, giving a pitted appear- 

 ance to the part." 



Mr. Cartwright accidentally met with a case of ossification in 

 the eye of a donkey. " The sclerotic coat appeared healthy, ex- 

 cept that a circle of bone existed near the optic nerve. There did 

 not appear to be disorganization of any other part of the eye." 



Mr. Charles Percivall, as I mentioned in a former place (at p. 87), 

 has in his museum a preparation shewing ossification of the retina. 



Besides these and other cases of the kind on record, there will, 

 in almost all veterinary museums, be found specimens of various 

 descriptions of ossification of parts of the eye. 



MELANOSIS. 



Professor Rodet discovered a remarkable kind of melanosis in 

 one of the eyes of a horse. The space usually occupied by the 

 vitreous humour was filled with a fluid as black as Indian ink, in 

 which floated equally black clots. The crystalline lens was of a 

 deep yellow colour, and in some parts even brown*. 



* For a good account of melanosis, consult AndraVs Treatise on Patho- 

 logical Anatomy, translated by Drs. Townsend and West. 



