2 Mr. Home's Lecture 



common membrane, which, by means of muscles belonging to 

 the malleus being stretched or relaxed, became fitted, in its 

 various degrees of tension, to convey the vast variety of ex- 

 ternal sounds to the internal organ. Its shape, situation, and 

 office, have procured it the name of drum of the ear ; and the 

 muscles of the malleus having been deemed sufficient for bra- 

 cing and unbracing it, less attention was bestowed on the struc- 

 ture of the membrane itself : to which may be added, that in 

 the human ear, and generally in the ear of quadrupeds, the 

 membrane is so extremely small and thin, and in its situation 

 so peculiarly confined, as not to be got at for inspection but with 

 much difficulty. 



The case is different in the elephant, where this membrane 

 is so very large, that the parts of which it is composed are 

 readily distinguished : they are even conspicuous to the naked 

 eye ; and muscular fibres are seen passing along the membrane, 

 in a radiated manner, from the bony rim which surrounds it, 

 towards the handle of the malleus, to which the central part of 

 the membrane is firmly attached. 



This discovery in the elephant having led to that of a simi- 

 lar construction in the human membrana tympani, it may not 

 be improper to relate the circumstances by which I became 

 engaged in the investigation of the organ of hearing in that 

 animal. 



Three different opportunities have occurred of dissecting the 

 elephant in London, by the deaths of those which had been 

 presented to his Majesty, and were kept at the King's stables 

 at Pimlico. One of them was given to the late Dr. Hunter ; 

 one to his brother Mr. J. Hunter ; and the third to Sir Ashton 

 'Lever. ds| 



