144 [June 19, 



seen to yield to the pressure, which takes place nearly at its central 

 portion. 



From the inspection of the vocal organs now so easily obtained, it 

 may be stated in general terms that, as the voice ascends from its 

 lowest to its more acute tones, the lengths of the vibrating portions 

 of the vocal cords are proportionally diminished, while at the same 

 time their tensions are increased ; and, in fact, they present the same 

 phenomena as those of musical chords, and they appear to obey the 

 same laws, as Ferrein so long since supposed, and which have since 

 been confirmed by Miiller and by myself. 



Moreover, the vocal cords form a kind of valve, which is situated 

 in a tube, and acts on the column of air in the manner of a reed. 



It is observed that while the pitch of the tones of the voice be- 

 comes more grave, the epiglottis is depressed and the pharynx is 

 relaxed ; and, on the contrary, as the pitch becomes more acute, the 

 epiglottis is raised and the pharynx becomes contracted : the de- 

 pression of the epiglottis probably assists in deepening the pitch 

 of the vocal tube in the same manner as the lid of an organ pipo 

 does. 



In the production and modulation of the voice, it is astonishing 

 with what accuracy some persons are able to produce at will, sounds 

 of a determinate pitch and of a quality which charm and captivate 

 the ear of a musician. The muscles which are principally con- 

 cerned in this faculty are the thyro-arytenoid and the lateral crico- 

 arytenoid. The crico-thyroid is limited to stretching the vocal liga- 

 ments. 



The mere turning of the vocal cords on their axes, out of the 

 vocalizing position, does not afford sufficient space for ordinary 

 breathing, as supposed by Mr. Willis, but we find that the arytenoid 

 cartilages and vocal cords are widely separated during ordinary 

 breathing. 



* With regard to the controversy as to whether the vocal organs are 

 to be considered as a stringed instrument or as a reeded pipe, it has 

 been thought by some physiologists that the same organs cannot 

 possibly perform the offices of both. However, under the denomi- 

 nation of reeded pipes, we find a great variety of form and structure, 

 and it is not difficult to conceive that while the time of an oscillation 

 of the vocal ligaments obeys the same laws as musical strings, the 



