Sensory Discrimination : Hearing 107 



But experiments upon coelenterates have entirely failed to 

 show that animals of this class react to sounds (in, 415,291). 

 And in some coelenterates, as well as in higher animals having 

 the same type of organ, the removal of the so-called otocysts 

 has been found to involve disturbance of the animal's power 

 to keep its balance and maintain a normal position. Hence 

 Verworn has suggested that for "otocyst" and "otolith" 

 the terms "statocyst" and "statolith" might appropriately 

 be substituted (415). In jellyfish, indeed, even the balancing 

 function of the statocyst organs appears doubtful; and it is 

 possible that they function in response to shaking and jar- 

 ring (286, 291). In any case, there is no evidence whatever 

 of a specific auditory sensation in the consciousness, if such 

 exists, of ccelenterate animals. 



Nor has any reaction to sound been demonstrated in either 

 the flatworms or the annelid worms; their sensitiveness to 

 vibrations seems to be an affair of mechanical stimulation. 

 Darwin's experiments on this point are well known. The 

 earthworms which he observed were quite insensitive to 

 musical tones, but when the flower pots containing their 

 burrows were placed on a piano, the worms retreated hastily 

 as soon as a note was struck (91). Most observers agree that 

 mollusks also react only to mechanical jars (e.g., 101), and 

 that the statocyst organs found in some mollusks have 

 no auditory function. Bateson, however, records that a cer- 

 tain lamellibranch, suspended by a thread in a tank, re- 

 sponded by shutting its shell when a sound was produced by 

 rubbing a finger along the glass side of the tank (12), and 

 Bethe demands to know of what possible use as static organs 

 the statocysts in fixed mollusks can be (27). The echino- 

 derms are apparently insensitive to auditory stimuli (350, 



365). 



