22 CHIKANOSUKE OGAWA 



open in five and closed in seven cases. The vesicles seemed to 

 make no rotation in the first three hours; some of them turned 

 back to the normal position within five to five and a half hours. 

 These experiments prove that the wound-healing process has 

 nothing to do with the rotation of the vesicles, because the latter 

 still remained in their position after the wound had healed com- 

 pletely. In other words, mechanical slipping back of the vesicle 

 due to the healing process, cannot be considered as the cause of 

 rotation. 



No examination was carried on between five and a half and 

 sixteen hours after operation. On examining the specimens from 

 sixteen to thirty-four hours after operation, it was found that 

 rotation was going on during these stages. Thus it was also 

 demonstrated that rotation can occur in a stage in which differ- 

 entiation of the semicircular canals, endolymphatic sac, and 

 other parts of the vesicle has not yet taken place and the ear is 

 represented merely by a round or oval vesicle, indicating only 

 some differentiation in epithelium. The number of rotated 

 vesicles in each hour did not show a constant increase in regard 

 to lapse of time, which was contrary to expectation. This may 

 be explained by the fact that in quite a number of the cases there 

 was not sufficient evidence by which to judge whether or not 

 the vesicles had rotated. Therefore, if these uncertain cases 

 were included,the total number and proportion of rotated and 

 non-rotated vesicles would undergo some change. 



Individual variation also may play a great part in rotation. 

 If specimens are studied in later stages, at a period when the 

 vesicles begin to show further differentiation and therefore 

 furnish more efficient criteria, we shall then be able to say with 

 some degree of certainty that the vesicles completed rotation at 

 a given time. I regret that, for this year, I have lost the oppoi-- 

 tunity of making such a study. 



