CHAP, vii.] SPECIAL MUSCULAR MECHANISMS. 1087 



from this that when the cords are adducted, the glottis must 

 always remain an isosceles triangle with the angle at the apex, 

 next to the thyroid, becoming more and more acute as adduction 

 proceeds, and that the parts of the cords in front, nearer the 

 thyroid, must come into actual contact before the parts behind, 

 nearer the processus vocales", do. But the laryngoscope shews 

 that the form of the membranous glottis is very varied ; it may 

 be open behind and closed in front, or closed both behind and in 

 front and open, even widely so, in the middle, or may be along 

 almost its whole length a slit with parallel sides, and in that 

 case either very narrow, a mere linear cleft, or of appreciable 

 width. And though the exact mechanisms are obscure, we can- 

 not doubt but that these several phases result from special 

 muscular contractions. 



4675. We might dwell on other changes which may by help 

 e laryngoscope be observed in the larynx during the pro- 

 duction of the voice, all shewing that muscular contractions 

 may produce complex and varied changes in the larynx besides 

 simple adduction or abduction and general tension or slackening 

 of the vocal cords; but we have said enough for our present 

 purpose, which is to insist that in the production of voice the 

 mere dimensions of the larynx, and we might add other natural 

 inborn features, serve but as the playground for muscular skill ; 

 it is the latter much more than the former which determines the 

 characters and the powers of the voice. A laryngoscopist, even 

 the most experienced, would probably hesitate from a mere in- 

 spection of the larynx to predicate the nature of the singing 

 voice. He could not even predicate the possession of a singing 

 voice of any kind. Of two larynges, provided they were both 

 of normal structure, he would be unable to say which belonged 

 to the man who could and which to the man who could not sing ; 

 for the power to sing is determined not by the build of the 

 larynx but by the possession of an adequate nervous mechanism 

 through which finely appreciated auditory impulses are enabled 

 so to guide the impulses of the will that these find their way with 

 sureness and precision to the appropriate muscular bundles. 

 And what is true of the difference between singing and not 

 singing at all is in a similar way true of the difference between 

 singing low and singing high, as Avell as of the difference 

 between singing saperbly and singing indifferently well. The 

 physiological difference between a bass voice and a tenor voice, 

 between a contralto and a soprano probably lies not so much in 

 the mere natural length of the vocal cords as in the constitution 

 of the nervous and muscular mechanism ; experience shews that 

 cords of the same natural length may in one individual be the 

 instrument of a bass, in another of a tenor voice, or in one indi- 

 vidual of a contralto, in another of a soprano voice. Again, 

 though the " magnificent organ " of a distinguished artist may 



