370 THE SENSORIAL FUNCTIONS. 



the touch at one time, and cold at another, (although its real 

 temperature has not varied,) according to the state of the 

 or«'an induced hy previous impressions: and a very different 

 judgment will be formed of its temperature, when felt by 

 each hand in succession, if the one has immediately before 

 been exposed to cold, while the other has retained its natu- 

 ral warmth. Similar phenomena may be observed with 

 regard to all the other senses: thus, the flavour of odorous, 

 as well as sapid bodies, depends much on the previous state 

 of the organ by which they are perceived; any strong im- 

 pression of taste made on the nerves of the tongue, render- 

 ing them, for some time, nearly insensible to weaker tastes. 

 Sounds, wliich make a powerful impression on the auditory 

 nerves, will, in like manner, occasion temporary deafness 

 with rcc;ard to faint sounds. The converse of this is ob- 

 served when hearing has been suddenly restored in deaf 

 persons, by the operation of perforating the ear-drum.* The 

 sensibility of the auditory nerves, which had not been ac- 

 cessible to impressions of sound, is found to be increased to 

 a morbid degree. This was remarkably exemplified in the 

 case of a gentleman, who, for several years, had been very 

 deaf, in consequence of the obliteration of the Eustachian 

 tube, so that he could scarcely hear a person speaking in a 

 loud voice close to his ear. As soon as the instrument which 

 had made the perforation was withdrawm, the by-standers 

 began to address him in a very low tone of voice, and were 

 surprised at receiving no answer, and at his remaining im- 

 moveable in his chair, as if stunned by a violent blow. At 

 length, he burst out into the exclamation, " For God's sake, 

 gentlemen, refrain from crying out so terribly loud! you are 

 giving me excessive pain by speaking to me." The sur- 

 geon,t upon this, retired across the room; unfortunately, 

 however, the creaking of his boots caused the gentleman to 

 start up in an agony from his chair, at the same time apply- 

 ing his hand instinctively to cover his ear; but in doing this, 



• Sec the note in p. 307 of this volume. 



f M. Maunoir, of Geneva, on whose authority I have given this account. 



