AUTHOR 8 ABSTRACT OF THIS PAPER ISSUED 

 BT THE BIBLIOGRAPHIC SERVICE, JUNE 27 



EXPERIMENTS ON THE ORIENTATION OF THE EAR 

 VESICLE IN AMPHIBIAN LARVAE 



CHIKANOSUKE OGAWA 



Kyoto, Japan 



TWENTY-FOUR FIGXTRES 



Several papers have been published by Streeter ('06, '07, 

 '14) on the remarkable phenomenon of automatic rotation of 

 ear vesicles to their normal position after having been inverted, a 

 fact which he first discovered in experimental studies on the tad- 

 pole. He found that when the ear vesicle of a larva of Rana 

 pipiens or Rana sylvatica was removed and replaced in the same 

 pocket in the reverse position (inside out) , at the end of two weeks 

 the operated vesicle had developed in its normal position. It 

 might well be assumed that the vesicle had simply slipped back 

 into its original position, since the vesicle, and any additional 

 fragment of mesoderm, would exactly fit the pocket from which 

 they were taken. In order to test this possibility he. removed a 

 vesicle from one specimen and transplanted it into the emptied 

 ear pocket of another. This procedure was followed by the 

 same results as the first. Further experiments demonstrated 

 that the cells constituting the ear vesicles become specialized 

 very early; moreover, that fragments of a vesicle may develop 

 independently of the rest of the structure. Streeter concluded, 

 therefore, that the posture of the membranous labyrinth is 

 determined by some influence which interacts between the 

 labyrinth and its environment. This interaction may be ex- 

 plained on the basis of one of three possibilities: 1) It may be 

 due to the intrinsic motility of the vesicle itself, such as is seen 

 in the healing of skin wounds of young larvae; 2) it may be that 

 the nerve and ganghon mass serve to draw the vesicle into its 

 proper position; 3) compression from the surrounding organs may 

 mechanically bring the vesicle back to its normal position. 



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