CATARACT. 365 



frequently produce great irritation, and penetrating ulceration 

 results, ending in panophthalmia and destruction of the eye. 



The therapeutic treatment of wounds of the sclerotic membrane 

 is identical with that of ulcers. 



DISEASES OP THE CRYSTALLINE LENS. 

 Cataract. 



All diseases of the lens, either of its substance or of its capsule, 

 as a rule, cause a certain amount of opacity, and may form one 

 or more star-like gray bodies in the centre of the lens itself (cata- 

 ract). It is not possible to enter into a description of the various 

 forms of cataract and its pathological alterations, but we will 

 only take up one form (gray) of cataract that can be subdivided 

 into two forms — soft, which may be congenital; or traumatic and 

 hard or contracted cataract, which is senile. The softening process 

 generally begins in the equator of the lens, and becoming diffused 

 soon causes a total opacity of light gray color. This may be streaked 

 with darker lines or it may have a mother-of-pearl discoloration, 

 with enlargement or distortion of the lens and a contraction of the 

 anterior chamber. This is very often seen in young animals. The 

 contracting process, on the contrary, begins in the shape of a num- 

 ber of small whitish strise, or dull opacities, in the peripheric layers 

 of the lenticular nucleus, and extend gradually over the cortical, 

 giving the lens a yellowish-white or yellow aspect after some time. 

 This is generally observed in old dogs (hard nuclear cataract, senile 

 cataract). The so-called capsular cataract does not, as a rule, de- 

 pend on true opacity of the capsule, but on an accumulation of 

 products of the same, which have been developed from disease- 

 processes which have gone on in its immediate neighborhood. For 

 instance, in inflammation of the iris. In some cases they appear 

 in small, star-like or streaked pigmented dull spots, which are 

 distinctly marked. 



ETioiiOGY. Gray cataract, as a rule, is a senile or old-age 

 affection, but it appears quite frequently in young dogs, and now 

 and then it is congenital. The author saw one case of hereditary 

 star cataract in connection with microphthalmus. The develop- 

 ment of' cataract which occurs in advanced as-e — that is to sav. 



