No. I.] THE VERTEBRATE EAR. 251 



clearly shown that these canals have no special or controlling 

 influence on the spatial relations of the body. 



It is manifestly important to determine what Sewall's and 

 Steiner's first results were due to, and Steiner carried on experi- 

 ments in the endeavor to answer the question. He observed 

 that in any Shark operated upon, whether the semicircular 

 canals were removed or not, when the instrument disturbed the 

 calcareous crystals covering the utricular sense organ, the ani- 

 mal immediately executed reflex motions or " Rollbewegungen," 

 and as a rule the fish rolls toward the side thus disturbed. 



When, however, both ears are thus injured, although the 

 "Rollbewegungen" set in, they are too complex to be analyzed. 



This investigator experimented with the utriculus by filling 

 the whole auditory cavity with melted paraffine of low melting- 

 point, and he found that such a procedure caused no disturb- 

 ance of equilibration. He concludes from this that, contrary to 

 what might have been expected, after the experiments on the 

 otolithic mass of the utricular sense organ, where rolling motions 

 followed each injury, that the function of equilibration resides 

 not in the ear in any part. As it was advisable, if possible, to 

 determine what causes produced the disturbance following dis- 

 placement of the utricular otoliths and possibly injury to the 

 nerve end cells of the utricular sense organ, Steiner carried on 

 experiments to that end, and found that the disturbance in the 

 motor mechanism is due to slight but certain and potent injury 

 of the acustico-facial nucleus in the medulla. The injury pro- 

 duces motions that are not to be distinguished from those 

 produced by section in this region of the medulla. Steiner 

 concludes that, everything considered, we do not need a special 

 explanation to account for the fact that careful cutting of the 

 ampullar nerves or any injury to the ampullar sense organs 

 which does not manage to reach the central nucleus, does not 

 call forth rolling motions. 



It is evident that Steiner's results cannot be due to a differ- 

 ence in character between the ampullary and utriculo-saccular 

 nerves, for each of the two branches of the auditory nerve sup- 

 ply ampullar sense organs and otolith-covered auditory sense 

 organs {e.g. the maculje utriculi and sacculi) ; and since it is 

 injury to the latter alone which apparently causes the equilibra- 

 tive disturbances and not of the nerves alone, it would seem 



