86 PERIODIC OPHTHALMIA. 



usual, wanting their jetty blackness, and on occasions exhibiting 

 light specks of opacity. Every subsequent attack will add to 

 these changes of structure. The cornea will, from interstitial de- 

 posit and thickening of substance, become opacous to that degree 

 that the internal parts are with difficulty distinguishable through 

 it; within, all appears darkened and gloomy, altered in colour and 

 texture ; in which state things remain, probably, until a fresh attack 

 supervenes and for a time renders matters even worse than they 

 were before : ultimately, however, with the decline of the inflam- 

 mation, comes the clearing away of this murky cloud, and once 

 more the iris and pupil become distinctly visible, but no longer in 

 the condition we last saw them, the iris being now changed into a 

 dark dead-looking substance, and the pupil, instead of being con- 

 tracted, being dilated, and assuming that glassy, greenish, yellow 

 cast which every experienced veterinarian but too well knows is 

 the sure omen of cataract. 



Cataract, forming in the manner it commonly does after oph- 

 thalmia, not from a single central or focal point, but by means of 

 whitish or greyish lines radiating throughout the substance of the 

 lens, puts an end to all useful vision, or so confuses it until perfectly 

 formed, that the little sight remaining is, perhaps, worse than none. 

 Inflammation returning — for, as I observed before, completed cata- 

 ract even will not always prove a bar to relapse — in the end there 

 will be either obliteration of the pupil, through adhesion of its 

 borders to the capsule of the cataractous lens, or else subsequent 

 dislocation of that body, through disruption of the iris into the an- 

 terior chamber, where it is seen lying in contact with the cornea, to 

 which it subsequently contracts adhesion. This total disorganiza- 

 tion of the globe of the eye is in after-years followed by a process 

 of internal absorption, the effects of which become manifest in the 

 shrinking and retirement of the eyeball within its socket, and in 

 the ultimate wasting and atrophy of it. 



The Dissection of Morbid Eyes, according to D'Arboval's 

 observations, shews an absence of any distinct chamber containing 

 aqueous humour; nothing, in fact, but a single cavity remaining. 

 Sometimes the iris appears lacerated, detached from the lens, re- 

 duced to a very small volume ; its capsule only remaining perhaps, 



