26o The Management and Diseases of the Dog. 



gnotny has long been recognised as an essential 

 part of the diagnosis, and that this characteristic in- 

 dication is largely due to the dull heavy eyes, 

 which are so commonly partially covered by the membrana 

 nictitans in rabies. Besides, the malady has a tendency to 

 be accompanied by catarrh of the conjunctivae, indicated by 

 a collection of mucus in the inner canthus of the eye. Be- 

 yond this, there sometimes suddenly appear circumscribed 

 opacities of the cornea, with breaking up of its texture in 

 the centre of these, and so leading to the formation of ulcers. 

 This ulceration progresses so rapidly, that in some cases 

 the substance of the cornea is perforated within two days. 

 These corneal ulcerations are not, however, very common:- 

 Siedamgrotzky had only observed them in six cases, in 

 which two or three ulcers appeared in both eyes. They 

 are not an accompaniment of only one form of rabies, but 

 appear in both — dumb as well as furious. On 2^ post-mortem 

 examination, it is found that the ulcer has penetrated the 

 cornea, in a conical manner, and that nothing but a thin 

 layer of fibrin, or a blood coagulum in the anterior chamber, 

 has prevented the escape of the entire contents of the organ. 

 Examined microscopically, the corneal ulcer offers no 

 essential difference from that witnessed in distemper: 

 moderate cell-heaping in the vicinity of the ulcer, fatty 

 degeneration of the corneal elements, and opening out 

 of the interstitial substance ; but nothing otherwise cha- 

 racteristic. , 



Siedamgrotzky at first believed that the alteration was 

 produced by mechanical causes, but from close observation 

 he is satisfied that it may appear in the quietest animals 

 whose eyes have not been exposed to external injury. It 

 is therefore not unlikely that an interruption in the nutrition 

 is the cause; though not a general alteration in the nutritive 

 function, but perhaps rather due originally to an alteration 

 in the trophic nerves of the eye. 



This explanation, of course, cannot be experimentally 



