ORIENTATION OF THE EAR VESICLE 29 



ROTATION OF THE EAR VESICLE WHEN TRANSPLANTED TO A 

 SPECIMEN OF A DIFFERENT ORDER 



As already stated, the rotation of the ear vesicle has heretofore 

 been studied only in the same individual or in individuals of the 

 same species. No one has as yet touched upon the question 

 as to whether vesicles, when transplanted in an inverted position 

 to individuals of a different species or of a different order reveal 

 the faculty of rotation. In other words, whether environmental 

 influence may extend to the organ of another species. For 

 studying this problem, Rana and Amblystoma were chosen, the 

 former belonging to Anura, the latter to Urodela. 



Transplanting vesicles from Amblystoma to Rana 



The ear vesicles of Amblystoma were first transplanted in .an 

 inverted position to Rana and examined after two weeks. For 

 judging the position, the endolymphatic appendage proved the 

 most efficient criterion because of its special location between the 

 brain and the labyrinth, and also because of its structure, con- 

 sisting as it does of cuboidal cells. The semicircular canals 

 may be also used as a guide. The lagena also takes a charac- 

 teristic position, projecting backward from the ventromedial 

 part of the vestibule. It is composed of intensely staining 

 columnar cells. 



The results of this experiment show, first of all that the ear 

 vesicle of Amblystoma is transplantable to Rana. As the speci- 

 mens were killed two weeks after the operation, it cannot be 

 stated with certainty whether or not the vesicles would have 

 developed to their final stage without any degeneration; but as 

 far as can be seen from a histological study of this stage, no sign 

 of degeneration could be noticed and the vesicles appeared quite 

 normal. It is therefore probable that they would have continued 

 to develop further. Coming back to the original problem, out 

 of fourteen cases, eleven showed complete rotation; one case did 

 not permit a decision,^ owing to its insufficient development ; the 

 other two cases contained no vesicles, the organs having probably 

 slipped out. Thus complete rotation occurred in almost all of 

 the specimens studied. The environmental influence is effective, 

 therefore, even for the ear vesicles of species of a different order. 



