36 CHIKANOSUKE OGAWA 



Different parts of the vesicle and its environment may act upon 

 each other differently. A certain part of the vesicle might have 

 a special or stronger positive or negative affinity for a certain 

 structure of the environment. By this force the vesicle may ad- 

 just itself to its normal posture. Since, however, the true nature 

 of chemotaxis is still unknown, we should hesitate to accept it 

 as a radical explanation. There arises now a question as to 

 whether the environmental influence is specific for the place 

 where the ear vesicle is normally present; in other words, whether 

 the inverted vesicle can regain its normal position in regard to 

 to the axes of the body when transplanted in an abnormal place. 

 I carried on some experiments along these lines transplanting the 

 ear vesicles in an inverted position under the skin near the tail 

 bud. Left in this position two weeks they gave no indication of 

 differentiation, but presented dropsical vesicles. I then examined 

 vesicles operated on in this way two days after operation. At 

 this time they showed no degeneration and a difference in the 

 thickness of the wall was discernible. I shall not, however, dis- 

 cuss this problem until I have made further experiments. 



LITERATURE CITED 



Kratjse, R. 1906 Entwicklungsgeschichte des Gehororgans. Hertwig's Hand- 

 buch der vergl. u. exper. Entwicklungslehre der Wirbeltiere, Bd. 2. 



Spemann, H. 1910 Die Entwicklung des invertierten Horgrubchens zum Laby- 

 rinth. Arch. f. Entwcklngsmechn., Bd. 30. 



Streeter, G. L. 1906 Some experiments in the developing ear vesicles of the 

 tadpole with relation to equilibration. Jour. Exp. Zool., vol. 3. 

 1907 Some factors in the development of the amphibian ear vesicles 

 and further experiments on equilibration. Ibid., vol. 4. 

 1909 Experimental observations on the development of the amphibian 

 ear vesicles. Anat. Rec, vol. 3. 



1914 Experimental evidence concerning the determination of posture 

 of the membranous labyrinth in amphibian embryos. Jour. Exp. 

 Zool., vol. 16. 



Uhlenhuth, E. 1913 Die synchrone Metamorphose transplantierter Salaman- 

 deraugen. Arch. f. Entwcklngsmechn., Bd. 36, S. 211. 



