240 Journal of Comparative Neurology. 



Delage believes that his experiment proves the equilibrium 

 function of the otocyst. 



He believes that the otocyst affects locomotion reflexly 

 and not by arousing sensations followed by voluntary acts. He 

 inclines, however, to the belief that this reflex control of loco- 

 motion is accompanied, or rather followed, by true sensations of 

 movement. "These sensations as well as the preceding reflex 

 acts may be aroused by the mechanical action exercised during 

 movements by the liquid or by the otoliths upon the nerve 

 terminations in the walls." The otocyst, according to Delage, 

 is a double organ mediating sensations both of sound and of 

 movement. According to his experiments sight and touch can 

 compensate largely for loss of the otocysts so far as locomotion 

 is concerned. 



n. GleichgewicJit jind Otolitlienorgan by Max Verworn, 

 Pfliiger's Archiv, V. 50, P. 423. 



After the appearance of Delage's paper Engelmann gave 

 public expression through the Zoologische Ajtzeiger, 1887, of 

 a view which he had privately entertained for several years. He 

 held that the otolith of the Ctenophors is "an apparatus for the 

 regulation of the equilibrium of the body." Verworn under- 

 took to prove Engelmann's conjecture experimentally. Of the 

 Ctenophors studied Beroe ovata gave the best results. This 

 species more regularly than any other assumed definite equilib- 

 rium positions. The animals come to rest with the body axis 

 in the vertical, either at the surface of the water with oral pole 

 directed upward or on the bottom with oral pole downward. 

 They are able, Verworn asserts, to change their specific gravity 

 and therefore the same individual is found at one time at the 

 surface in the first position, at another time on the bottom in 

 the second position. . If Beroe, standing at the surface with its 

 mouth directed upward, was carefully turned by means of a 

 glass rod into some other, say the horizontal, position, the 

 swimming plates of the under side immediately began making 

 vigorous strokes toward the aboral pole, while those of the up- 

 per side remained quiet. As a result, the animal turned back 

 toward the vertical resting position. Just before it reached the 



