OEIENTATION OF THE EAR VESICLE 31 



Protocols of experiments 



Transplantation from Amblystoma to Rana. Specimens A II, A III, 

 B II, C I, C III, D II, and E I (figs. 17 to 20) show the labyrinths in 

 normal position. The endolymphatic appendage lies between the 

 brain and the labyrinth. Dorsal and anterior is the anterior semi- 

 circular canal; dorsal and posterior, the posterior semicircular canal; 

 lateral, the lateral semicircular canal. From the lower and medial 

 part of the labyrinth chamber the lagena buds out posteriorly. The 

 acousticofacial ganglion is attached medially to the labyrinth. 



B J . The endolymphatic appendage is in nonnal position. The 

 lateral and posterior semicircular canals are normally formed, but there 

 is no anterior semicircular canal. The labyrinth is a little abnormal, 

 but is in normal position. 



C II (fig. 21). The vestibule is exceedingly large. The endolym- 

 phatic appendage is in its normal position. The lateral semicircular 

 canal is not sufficient^ closed, being represented by a groove, but its 

 position is normal. The anterior semicircular canal is not formed 

 The posterior semicircular canal deviates slightly from the normal 

 position. The lagena is incompletely formed. The labyrinth is in 

 normal position. The acousticofacial ganglion is attached in normal 

 position. 



D I. The anterior semicircular canal presents an appearance as if 

 it had been pressed against the brain. The endolymphatic appendage 

 is situated a little higher than normal. The lateral and posterior 

 semicircular canals are in proper position. Below the labyrinth there 

 is an enclosed cavity, the medial wall of which is covered by columnar 

 cells. This cavity is separated from the labyrinth by a thin wall, 

 and no connection between them could be observed. The nature of 

 the ca\'ity is not clear. Though abnormal in formation, the labyrinth 

 is still in its normal position. 



E II. The labyrinth vesicle has not developed far. The endolym- 

 phatic sac can be seen in normal position, but aside from this, the 

 vesicle shows practically no differentiation. The wall is covered by a 

 simple layer of flat cells, while the basal part is lined by several layers 

 of flat cuboidal cells. Though the vesicle itself does not reveal the true 

 characteristics of the developed ear, there is still sufficient evidence to 

 justify the conclusion that it is in normal position. 



D III. Differentiation of the semicircular canals has not as yet 

 occurred. The vesicle is lined bj^ a simple layer of epithelial cells 

 which are flat in the upper part and take on a cuboidal form in the 

 lower. Medioposterior to the vesicle is another which has no con- 

 nection with it. The lower part is covered by a layer of columnar 

 cells and the remaining part by cuboidal cells. The medial wall is 

 disassociated. The nature of this second vesicle is not clear; it may 

 or may not represent the developed stage of a surplus vesicle, such as 

 was found in several cases in the study of inverted vesicles in the early 

 stages. 



A I, B III. No vesicle found. 



