Development of Amphibian Ear Vesicle 439 



from which the right vesicle had been taken and allowed to heal. 

 In making the transplantation no effort was made to place the 

 ear vesicles in any particular posture. After keeping the speci- 

 mens alive for one month they were sectioned and from three of 

 them reconstructions were made of the transplanted ear vesicle 

 together with the adjacent structures. The three labyrinths are 

 shown in Fig. 6, and model c is again shown in Fig. 5, with the 

 brain included. It will be seen that in developing they have 

 assumed the normal attitude toward the brain. The endolym- 



sac. endolymph. 



lagena 



Fig. 6 Reconstructions of three labyrinths which while primitive ear vesicles were transplanted 

 from the left to the right side. They are all represented in the same position as the models in Fig. 2. 

 The model c is the same that is shown in Fig. 5. Enlarged 50 diameters. 



phatic appendage and the median side of the labyrinth is toward 

 the brain, the semicircular canals are toward the dorso-lateral sur- 

 face, and the saccule and lagena are toward the ventral surface. 

 But it can at once be recognized that the saccule and lagena point 

 forward toward the eye, and that the anterior and posterior canals 

 are in reversed positions. We thus have a complete mirror image 

 of the right labyrinth, /. e., a left labyrinth. Model a possesses 

 three semicircular canals and is almost a normally formed left 

 labyrinth. In model h the lateral canal consists of a pouch whose 

 walls did not undergo the customary approximation and central 

 absorption. In model c the posterior canal is not pinched off. 

 In each of the models the lagena, saccule, and endolymphatic 



