Drvrlopmnit of A ))i phihi an Ear rrsiclc 441 



were still (juite imperfect in the formation of the separate cham- 

 bers and the semicircular canals. So this year in carrying; out the 

 experiments described in the first part of the present paper the 

 behavior of the specimens was eagerly watched, and the endeavor 

 was made to determine the amount of alteration in position and 

 defectiveness in form that is compatible with functional activity, 

 involving the problem of the correlation between function and 

 morphology. The observations made in the different experiments 

 have been arranged and condensed as follows: 



a Left ear vesicle removed; right ear vesicle loosened from 

 skin and rotated, in six specimens around the vertical axis 180° 

 and in eight specimens around both the vertical and transverse 

 axis 180°. As has already been shown these ear vesicles developed 

 into labyrinths of varying degrees of perfection, some being com- 

 pletely normal in form and having apparently normal ganglion 

 and nerve connection with the brain wall. (See Figs. 2, 3 and 

 4.) The behavior of all the specimens was uniform, both where 

 the ear vesicle was rotated in one plane and where rotated in two 

 planes; at the end of a week after the operation, when with a nor- 

 mally functionating labyrinth they should be able to swim freely 

 and directly, they instead exhibit only irregular movements or spin 

 around in spirals or circles. Their incoordinate movements con- 

 tinue, and at the end of a month there is no improvement; i.e, they 

 behave exactly like specimens with both ear vesicles removed. 

 Evidently ear vesicles thus treated do not perform their natural 

 function. 



b Left ear vesicle removed; right ear vesicle fragmented by 

 teasing between the points of two needles, the fragments left in 

 place. Ten specimens were treated in this way, and were kept 

 under observation four weeks, during which time they gave no 

 evidence of any sense of equilibrium. 



c Right ear vesicle removed; left ear vesicle transplanted to 

 the empty pocket on the right side. Five specimens were oper- 

 ated upon and observed for one month, at the end of which time 

 they were cut in serial sections, and it was found that the ear vesi- 

 cles had developed into fairly complete labyrinths, but had main- 

 tained the characteristics of a left-sided organ. (Figs. 5 and 6.) 



