Developiiinif of Arjiphibian Ear Vesicle 443 



showed that they were not perfectly normal. This experiment 

 might be repeated on a larger number of specimens and still 

 greater care used in severing the nerve connection, in which case 

 a perfect labyrinth could doubtless be obtained. 

 . h (Rana catesbiana) Left ear vesicle transplanted into an- 

 other specimen, in a subdermal pocket in the region of the pro- 

 otic ganglion betw^een the right eye and ear vesicle, thus the host 

 had three ear vesicles, two being on the right side. Twelve days 

 after the operation three out of four specimens so treated exhib- 

 ited incoordinate movements. Here we have to consider the 

 crowding out of position of the normal right ear vesicle by the one 

 transplanted near it. 



/ Left ear vesicle removed; fine needle passed through the skin 

 so as to make a small puncture m the right ear vesicle; on with- 

 drawal of the needle the edges of the wound immediately close and 

 there is no loss of cells from underneath or from the skin itself. 

 Of four specimens at the end of one month three were able to swim, 

 and this demonstrated the functional ability of an ear vesicle thus 

 treated. 



/ Left ear vesicle removed; small section of the covering skin 

 removed so as to expose the right ear vesicle, but otherwise it is 

 not disturbed and the nerve ganglion connection is left intact. 

 Five specimens were kept under observation for one month, and 

 tour of them behaved throughout like those possessing one 

 untouched normal ear vesicle; except for slight incoordination 

 brought out by excitement they could swim properly. 



Onbringingtogether the results of these experiments, it becomes 

 immediately apparent that almost any operative procedure car- 

 ried out on young larvae in the region of the ear vesicle seriously 

 interferes with the development of the function of that organ. It 

 is possible to lift a skin flap and expose it, and to make a needle 

 puncture in it without destroying its subsequent usefulness; but 

 any operation involving a loss of part of its wall or disturbing its 

 position and nerve-connection with the brain causes apparently 

 complete loss of function. The functional disturbance is out of all 

 proportion to the histological condition. There may be a laby- 

 rinth that to all appearances is perfectly formed and that seems to 



