384 



REMOVAL OF CtENURUS CEREBRALIS. 



opening the cranial cavity the thinned and protruding dura mater 

 must be divided, and the bladder and contents removed with forceps. 

 The wound in the skin is then closed with catgut or silk sutures, 

 powdered with iodoform, and covered with an adhesive ; though 

 frequently only a tar bandage is applied to the skull to protect fche 

 wound from flies. 



Moller's experience with trephining has not been favourable, 

 and he prefers the trocar. The following is the method of pro- 

 cedure : — The animal is laid on its side on a table, the surface 



of the skull shorn, and the skin 

 disinfected. In rams having large 

 horns, where the skin inclines to 

 form folds, this is rather difficult. 

 The trocar is provided with a 

 cannula suitable to the thickness 

 of the skull, that is, one in which 

 the round shield is not much 

 further from the end of the cannula 

 than the thickness of the skull. 

 so that the instrument shall not 

 puncture the brain (Fig. 337). 

 With some care and practice, how- 

 ever, this appliance is not required. 

 It must be remembered that the 

 thickness of the skull varies con- 

 siderably ; in ewe lambs it may 

 only be a few lines ; in rains with 

 large horns it is often more than 

 I of an inch. The point of the 

 trocar (previously disinfected by 

 boiling), being directed towards 

 the middle line and backwards, is thrust through the roof of the skull 

 by semi-rotary movements. 



The stilette is then removed, and if the bladder has been punctured 

 its clear serous contents begin to escape through the cannula. After 

 spontaneous discharge has ceased, the empty syringe (Fig. 33G) is 

 inserted through the cannula, and any remaining fluid removed. 

 The syringe is held in the right hand with the thumb in the ring of 

 the piston, and the point towards the little finger. Inserting it 

 about as far as the cannula penetrates, the piston is slowly drawn 

 up by the thumb, and the process is repeated as often as required. 

 A portion of the sac-wall may enter the syringe, when resistance 



Fig. 337. Zehden' 



trocar. 



