Lyon, Functions of the Otocyst. 239 



from permanent after-effects due not to the removal of the or- 

 gans but to injury to remaining parts. 



If only the otocysts were removed from these animals, 

 they swam normally and no peculiarities were observed in their 

 behavior. But when in addition the eyes were removed, the 

 animals were "completely disoriented." Even many days after 

 the operation, when the wounds had entirely healed and the ani- 

 mals had recovered their normal activity and appetite, " correct 

 and normal swimming remained impossible." But it is impor- 

 tant to observe that forced movements were present. For 

 hours, even days at a time, the operated animals would roll 

 around a longitudinal axis in one constant direction or turn 

 somersaults. Such appearances would seem to indicate some- 

 thing besides a loss of equilibrium. In spite of the apparent 

 excellency of this animal for such experiments, it is probable 

 that some one-side injury to the nervous system resulted from 

 the operations. 



The extirpation of neither eyes nor otocysts alone was suf- 

 ficient to cause disturbance of equilibrium. But loss of the 

 eyes and mutilation equivalent to taking away the otocyst-con- 

 taining lamella; of the tail but without molesting these (for 

 instance, cutting away the outer tail-pieces) caused no equilib- 

 rium disturbances. Therefore Delage infers that the inner la- 

 mellae with their otocysts are not a mere mechanical factor to 

 equilibrium but that the otocysts constitute a true geotropic or- 

 gan regulating the orientation of the animals with reference to 

 the direction of gravity. 



Experiments on the decapod Pakemon gave somewhat 

 similar results. Loss of the antennules with the contained oto- 

 cysts caused no difficulties of locomotion. Hardly any troubles 

 followed loss of both otocysts and eyes. J3ut when in addition 

 the filaments of the antennae were cut away, the animals were 

 manifestly and permanently disoriented. It is likewise imagin- 

 able that if a man had both legs, both arms and both eyes re- 

 moved, he would have some trouble getting about in the world. 

 However, as animals equally mutilated but without disturbing 

 the otocysts were not troubled in the same degree and manner. 



