8 C. WINKLER. THE CENTRAL COURSE 



in the post-mortem by loss of substance or by softening seen with 

 the naked eye, but only shown in microscopical investigation as 

 the origin of a MAHCHI degeneration , is no longer suited for follo- 

 wing the course of the Nervus VIII by means of the MARCHI- 

 method. Such pigeons are moreover likewise useless for the physiology 

 of the Nervus VIII. 



On pigeons the operation is more difficult than on rabbits, and 

 even therefore it is necessary to make preliminary trials in remo- 

 ving the labyrinth on these animals, before experimenting on rabbits. 



However, E\VALD has described this operation on pigeons so 

 minutely in all its subordinate parts, that, guided by him, it will 

 be easy to obtain the experience that will be useful in experimen- 

 ting on rabbits. Still, I am of opinion, like EWALD, that the suc- 

 cess of the experiment i. e. the appearing of the functional troubles 

 (that are always the same after extirpation of the labyrinth) depends, 

 next to the post mortal assertion of the fact that only a lesion of 

 the Nervus VIII has been produced, on asepsis and on the tech- 

 nics of the operation. 



For my purpose five operations have been found necessary to 

 elucidate the central course of the rierous VIII. 



1. the isolated removal of the cochlea, 



2. the removal of the cochlea together with the contents of the 

 vestibulum, 



3. the operation mentioned sub 2 -f- the section of the N. octa- 

 vus in the meatus auditorius interims, 



4. the section of the ventral octavus-tract (the corpus trapezoides), 



5. the amotion of the tuberculum acusticum and the nucleus 

 ven tralis N. VIII together with the dorsal octavus-tract (MoNAKOw's 

 stria medullaris in the rabbit). 



The first four of these operations were performed through the 

 bullea ossea, the last one from the 4 th ventricle. 



I will therefore begin with the description of the operations at 

 the bulla ossea, before proceeding to that from the 4' h ventricle. 



It must be remarked previously, that all animals destined to be 

 operated, are prepared the day before. 



The skin over the region of the operation is shaven and carefully 

 cleansed with soap, alcohol and sublimate. I hold a repeated dis- 

 infection of the skin on the day before the operation and imme- 

 diately before operating, to be necessary. The great difficulty in these 

 operations is the disinfection of the skin. It is to the minute skin- 

 disinfection that I attribute the favorable results and the absolute 

 aseptic woundhealing. 



