Semi-circular Canals of Ear to Motor System. 9 



first appearance of head pigment was found to be really a case 

 of the combination of two crops of head chromatophores, one of 

 which did not develop in the recessive species F. majalis. 



7 (616) 



A note on the relation of the semi-circular canals of the ear 

 to the motor system. 



By J. GORDON WILSON and F. H. PIKE. 



[From the Laboratories of the University of Chicago and Northwestern 



University.] 



The work on the semi-circular canals was undertaken with 

 the object of studying: (1) The results of stimulation of the 

 end organ of the vestibular nerve; (2) the immediate and remote 

 results of destruction of the labyrinth or of the eighth nerve on 

 one or both sides; (3) the effect of removal of various parts of 

 the brain on phenomena which have been observed to follow 

 stimulation or destruction of the labyrinth, and (4) the paths of 

 nervous connection between the labyrinth and the eye muscles — 

 the optico-acoustic path. Later it is the intention to study 

 anatomically the degenerative processes occurring in various parts 

 of the central nervous system after destruction of the labyrinth 

 or eighth nerve. 



Method. — The mastoid bone is exposed by a skin incision and 

 the separation of the muscles from their attachment at the linea 

 nucha? superioris and the anterior inferior border of the pars 

 mastoidea. A trephine opening is made through the outer table 

 and diploe of the mastoid bone. The hard portion of the otic 

 bone, in which the semi-circular canals are imbedded, can be 

 removed with a mastoid gouge and the labyrinth destroyed without 

 direct anatomical injury to the cochlea. Dogs, cats and tortoises 

 were used. The results here given apply to dogs, unless other- 

 wise stated. 



Results. — Immediately following recovery from the anesthetic 

 after removal of one labyrinth, there is marked torsion, particu- 

 larly of the anterior part of the body, of the animal toward the 

 injured side. The animal is unable to walk and falls over toward 



