DIFFICULTIES TN REMOVING (XENURUS CEREBRALIS. 387 



precautions. Merkt, who is supported by Albrecht, describes the pro- 

 cedure as follows : — 



An incision about 1| inches long is made through the skin parallel 

 with, and distant f of an inch from the middle line. The incision should 

 not be commenced too high, as in that direction the two plates of the 

 temporal bone lie wider apart. At right angles to this incision a second, 

 about 1 inch in length, is made and then the second longitudinal cut. An 

 assistant, kneeling behind the animal's head, holds back the flap with a 

 hook, the exposed periosteum is carefully removed and a hole about 

 | inch in diameter is made with a trephine. This exposes the inner or 

 cranial plate of the temporal bone. Very often, however, this cranial 

 plate is in contact with the outer or has become absorbed ; if not it must 

 be removed with the gouge, bone forceps or bone screw, as it can 

 seldom be reached with the trephine. In any case the trephine must be 

 used cautiously and the cut made slowly, to prevent the instrument 

 suddenly breaking through and so injuring the brain. Where the second 

 plate exists it is necessary to remove with bone forceps all the thin, 

 softened portions of bone covering the cyst so as to facilitate removal of 

 the bladder, which is often of large size. 



Having at last produced a hole about \ an inch in diameter, the brain 

 will be seen, in favourable cases, to be pressing against the edges, and 

 on incising the meninges the distended bladder will at once protrude. 

 As soon as this occurs, the straw bedding should be removed from below 

 the affected side of the head so as to allow it to descend and thus render 

 removal of the bladder easier. The cyst usually bursts spontaneously ; 

 if not it can be ruptured with a director, after which the wall is cautiously 

 grasped with forceps and withdrawn. 



The point of operation is then cleansed and the skin flap simply laid 

 in place. The wound always heals readily. After-treatment consists in 

 keeping the animal quiet and the wound undisturbed. The entire body, 

 including the head, is clothed and the animal allowed to lie until the 

 temporary period of stupefaction has passed. When energetic struggles 

 begin and the patient, lifting the head, attempts to rise, the hobbles 

 are removed. Sometimes twelve hours elapse before this occurs. In such 

 cases the results are always much better than when the patient gets up 

 quickly. 



The animal is supported to a stall, into which it is placed backwards. 

 A strong sack or length of cloth is sewn together so as to form a collar to 

 envelop the lower part of the neck, and to this are attached two ropes 

 which are fastened respectively to two posts driven firmly into the ground 

 at a distance apart of one yard. This keeps the animal in position without 

 touching the head. If it goes forward it hangs in the sacking collar ; if 

 back it meets the wall. The eyes should be bandaged and the stable 

 kept perfectly quiet. Animals sometimes recover very rapidly — even in 

 a few hours. 



