• S. S. MAXWELL 125 



left both eyes look to the right. If in these rotations the new position 

 is retained, the new position of the eyes is not retained; they return 

 to their primary position. It is seen at once that in the new position 

 there is no altered relation to the Knes of gravitational force. 



Removal of the Ampullce. 



The ampullae of the anterior vertical and the horizontal canals 

 open into the utriculus so near the macula acustica of the latter that 

 most experimenters seem to have had difi&culty in destroying the 

 one set of structures without injury to the other. Lee^ and Lyon^ 

 each speak of destruction of the ampullae, but both seem to have 

 rehed on section of the nerve branches. By section of the nerve 

 branches, however, they arrived at exactly opposite and fundamen- 

 tally contradictory results. 



After considerable practice I have developed a special technique 

 by which the ampullae of any or all of the canals may be removed 

 with a minimum of injury and shock to the animal and with results 

 which admit of no uncertainty. A flap of skin is loosened and turned 

 back exposing the appropriate portion of the skull. A thin surface 

 layer of the skull is sliced off with the attachment of some of the 

 neck musculature, thus making visible the parts of the labyrinth 

 through the transparent cranial cartilage. The membranous canal 

 is exposed at a distance not too great from its ampullar enlargement. 

 With a fine pointed pair of curved forceps the membranous canal is 

 grasped as closely as possible to the ampulla and the canal with its 

 ampulla is extracted by a sudden movement, a hght quick jerk. 

 Success in this operation depends mainly upon the choice of forceps 

 with the proper curve which bite at the very point, and upon acquir- 

 ing the knack of removal of the canal by a suitable movement. A 

 too sudden pull will usually break off the canal external to the ampulla, 

 and too slow a movement frequently drags and injures portions of the 

 vestibular structures which it is desired to leave unharmed. When 



^ Lee, F. S., A study of the sense of equilibrium in fishes, /. Physiol., 1893, 

 XV, 311. 



^ Lyon, E. P., A contribution to the comparative physiology of compensatory 

 motions. Am. J. Physiol., 1899-1900, iii, 86. 



