USES OF THE TARTS IN THE EAR. 



331 



With regard to the last mode, I can conceive no 

 cavity less suited to convey sounds. Instead of 

 having a definite form like the tube of the ear, 

 by which the vibrations might be received and 

 directed inwards, the tympanum opens into the 

 cells of the temporal bone, and presents the most 

 irregular surface possible, and such as would in- 

 evitably break and destroy any regular sound. 

 The extension of cavity of the tympanum is cal- 

 culated to increase the elasticity of the air in the 

 tympanum, but most certainly not to collect or to 

 strengthen the sound. 



With regard to the labyrinth, comparative 

 anatomy lends us considerable assistance. Were 

 vibrations of sound being communicated to the 

 brain the cause of hearing, the brain itself would 

 be the organ and no special nerve necessary. 

 The brain in some animals, being placed in a 

 cavity, and surrounded with fluid, is subjected ne- 



This figure represents the form of the brain in the cuttle-fish, as 

 an example of its very simple structure : a the simple auditory 

 apparatus. 



