Lyon, Functions of the Otocyst. 241 



vertical, the plates hitherto inactive would begin vibrating, so 

 that any swinging beyond the vertical was prevented. For any 

 change from either equilibrium position the general result was 

 the same, namely a definite and orderly series of movements 

 bringing the animal back to its normal resting position. 



The otolithic apparatus in the Ctenophors is situated at 

 the aboral pole at the junction of the eight meridional ciliated 

 grooves which run from the otolith toward the oral pole and 

 broaden out into the swimming plates. These plates, indeed, 

 are composed of cilia joined together. The otolith could be 

 seen easily through the transparent apical tissues. In some 

 species it could be removed by thrusting a glass tube through 

 the unresisting substance and sucking away the stone. In Be- 

 ne it was necessary to burn out the stone with a hot needle. 

 After the operation, although the animals recovered from the 

 shock and ate like normal individuals, they never again assumed 

 definite equilibrium positions. It was noticable, however, that 

 the different rows of swimming plates of the operated animals 

 were entirely independent of each other. Each now maintained 

 its own rhythm. Some rows would be motionless for consider- 

 able periods, while others were in active vibration. This Ver- 

 worn thought due to the destruction of the regulating appara- 

 tus. But Romanes and others have shown that any break in the 

 tissue connection of the ciliated furrows leads to independent 

 rhythm in the different rows of plates, under which condition 

 it is not to be expected that any definite resting position would 

 be assumed. The validity of Verworn's conclusions has been 

 doubted on this ground. It has been asserted that he destroyed 

 the unity and therefore the coordination of the locomotor sys- 

 tem and even though the animal might have twenty geotropic 

 organs, it could no longer assume its characteristic orientation. 



In anticipation of this criticism, Verworn introduced a 

 sharp needle through the mouth of several Ctenophors and at- 

 tempted to destroy the tissue lying under the otolith without 

 disturbing the latter. After a few minutes the animals assumed 

 the equilibrium position. Such experiments are however of 

 doubtful value and the criticism of Verworn's work retains 



