DISEASES OF THE MEMBRANA NICTITANS. 743 



^th more or less suppuration, lacrymation and ectropion of the 

 lower lid. 



The epithelial growths, when small, will sometimes disappear 

 under the appHcation of caustics, or can be removed with the 

 ligature, or by direct amputation with fine scissors. In some 

 cases they assume very large dimensions, the mucous membrane 

 becoming more or less ulcerated, and the cartilage itself diseased, 

 and amputation of the entire cartilage becoming necessary. 



This operation is not of recent origin, having been per- 

 formed, within our knowledge, some years ago, though entirely 

 upon empirical grounds, in tetanic cases, from the fact that 

 the protrusion of the membrana nictitans over the inner side 

 of the external surface of the ocular globe, quite out of its nor- 

 mal position, had often been noticed among the symptoms of 

 lock-jaw. The removal of the '' hawck^'' as the operation was then 

 called, has never, however, for the reasons which were them ac- 

 cepted, become legitimized among the therapeutics of the scien- 

 tific veterinarian. The removal of part, or what is more effectual, 

 of the whole of the membrana nictitans requires three instru- 

 ments, a speculum ocuh, a special forceps, like that of Snellen, 

 and a pair of curved blunt scissors. 



The animal must be thrown, and the eye being anestheticised 

 with cocaine, and the lids kept well apart with the speculum, the 

 organ, with the mucous membrane which covers it, is drawn out 

 •with the Snellen forceps, and by degrees severed in its continuity. 

 "UTien it is loosened sufficiently to be brought entirely out of the 

 orbital cavity, it is separated with the scissors from all its attach- 

 ments. The adipose mass which was then slightly i)rotruding re- 

 turns to its position and the operation is concluded. 



There is always a little hemorrhage accompanying the dissec- 

 tion, which, however, is readily subdued by means of a simple 

 compress of cold water. No special subsequent attention is neces- 

 sary. 



n. — Operations on the Lachrymal Apparatus. 

 A. — On the Caruncula A2yparatus. 

 The caruncula lachrymalis is sometimes the seat of hypertro- 

 phy, as commonly seen in cattle, the vague designation of Encan^ 

 this being given to all such lesions of the caruncula lachrymalis, 

 whatever may be their origin or nature. 



