ORIENTATION OF THE EAR VESICLE 27 



E II (fig. 9). Vesical oval. The ventral wall is thick; lateral wall 

 thin and flat. The whole appearance suggests complete rotation. 



F I. Vesicle round; dorsomedial wall thick. The ganghon is attached 

 to the ventromedial wall. Rotation probably is incomplete. 



F II. Vesicle large and of oval shape. The lateral wall is flat. 

 The whole appearance suggests complete rotation. 



F III. No vesicle. 



Examination 26 hours after operation. 



A I. This vesicle presents an oval form. The wall is thick ventro- 

 medially. The ganglion is attached to the lateral wall. If the thick- 

 ness of the wall is taken into account, the vesicle must have rotated, 

 but the position of the ganglion speaks rather against such an assump- 

 tion. Position is difficult to determine. 



A II. The vesicle lacks the necessaiy criteria for decision. 



A III. Vesicle round. The dorsal wall is thick, ventral wall thin. 

 The ganglion is attached to the ventral wall Rotation is not complete. 



B I. The vesicle is large The wall which turns cerebrally, is 

 flat. This seems to have been due to pressure from the vessel which 

 Hes between the vesicle and the brain. The ganglion is attached to 

 the ventral wall of the vesicle. Efficient criteria lacking. 



B 11. No vesicle. 



C I. The vesicle is large. The dorsomedial wall is thin. One part 

 of the dorsal wall is elongated upward. Position is difficult to 

 determine. 



C II. The wall is thin ventromedially and thick dorsally. The 

 ganglion is attached to the ventral wall. No rotation. 



C III. The vesicle is too small to admit of a definite decision. 



D I (fig. 10). The vesicle is shghtly oval. The wall is thick ven- 

 trally. The whole appearance suggests quite normal position. Rota- 

 tion is complete. 



D II (fig. 11). The vesicle is round. The dorsal and medial walls 

 are thick, while the ventral wall is thin. Rotation not yet completed. 



Examination 28 hours after operation. 



A I. Specimen incorrectly cut and no vesicle was found. 



A II. No vesicle found. 



A III (fig. 12). The vesicle presents an oval shape. The wall is 

 thick ventrally and thin laterally. In the ventro-anterior part the 

 cavity is divided into two parts. The vesicle shows a dorsal pro- 

 longation which suggests formation of the endolymphatic appendage. 

 Rotation is complete. 



B I. The vesicle is round; the ventral wall thick. Position difficult 

 to determine. 



B II. Vesicle slightly oval. The wall is thick ventromedially. 

 Rotation is complete. 



B III (fig. 13). The vesicle is quite oval, the ventromedial wall 

 tliick. The ganglion is attached to the medial wall. Rotation is 

 complete. 



C I. The wall of the vesicle is thick ventromedially' and thin laterally. 

 The ganghon is attached to the medial wall. Rotation is complete. 



