160 



OPERATIONS. 



out, and are dissected back so as to expose the skull. 

 The yielding portion of the latter is then pared away, 

 wtiich brings the sac into view. This will be seen 

 alternately to sink and rise, following in this respect 

 the motions of the brain. A moderate-sized needle, 

 slightly curved and filled with thread, is now passed 

 through the exposed portion of the cyst, and the thread 

 allowed to remain. The fluid is thus permitted slowly 

 to escape, and at the same time the sac becomes col- 

 lapsed, after which it is easily removed by pulling 

 gently at the thread with which it is connected. As 

 good a hold should be taken with the string as possible, 

 and all the water should be allowed to flow out before 

 any attempt is made to extract the remains of the 

 hydatid. To conclude the operation, lay down the 

 flaps of skin in their original position, covering them 

 with a small piece of folded linen smeared with lard, 

 and over all apply a cap. Never try to save the bone 

 which you cut, by turning it back in the form of a lid, 

 for by so doing you will only endanger the life of the 

 animal, which is otherwise in little jeopardy. 



It will often happen that the hydatid, from being in 

 the interior of the brain, will not be brought into view 

 by the removal of a portion of the skull. In this case 

 the brain must be punctured in order to reach the sac 

 and evacuate its contents. 



When the skull above the eye is very thin, the disease 

 may be at once ended by cautiously thrusting a short, 

 stout, sharp-pointed piece of steel wire through the skin 

 and bone down towards the centre of the brain, taking 

 care to pull the skin a little to one side before making the 

 puncture, so that on letting it loose the openings in the 



