338 VOCAL APPARATUS, L.ECT. XVIII. 



may modify the intensity and even the tone of the sound 

 produced in the glottis. Finally, we may consider the 

 larynx as a cylindrical cavity, having two orifices in the 

 centre of its bases. Assuming that a current of air tra- 

 verses this cavity with different degrees of rapidity, that 

 the diameters of these orifices are variable, and that the lips 

 of its orifices, which are endowed with a variable tension, 

 are elastic, we can easily conceive that a great variety of 

 sounds may be produced by this apparatus. 



Analogy of the Organ of Voice to Musical Instruments. 

 These considerations explain why the organ of the human 

 voice, and the voice of animals, has been compared at one 

 time to a stringed, at another to a wind instrument; some- 

 times to a reed instrument; and, lastly, by Savart, to the 

 bird-call. I must pass over in silence the long and minute 

 explanation of the reasons assigned by the various authors 

 in support of their different opinions concerning this organ. 

 I do this the more willingly because I think we shall find, 

 at the end of this lecture, that these theories of the voice 

 are not so opposed to each other as their authors have 

 imagined. 



Let us be guided, as usual, by experiment. All parts 

 of the larynx may be removed without destroying the voice, 

 provided that the vocal cords are preserved : these latter, 

 then, are the indispensible elements of the apparatus ; and 

 if we consider that they may undergo a more or less con- 

 siderable degree of tension, by varying the opening left 

 between their edges, we cannot but consider this essential 

 part of the vocal organs as a reed instrument, with a mem- 

 branous tongue of a peculiar construction. The other parts 

 of the larynx, as well as the entire superior cavity of the 

 mouth, form the pipe of the reed instrument; and the in- 

 ferior part of the trachea constitutes the ordinary tube which 

 proceeds from the. bellows. We are indebted to Weber, 



