OF THE VOICE. 41 



Worms and insects have no true voice ; for we must not 

 mistake for it, the buzzing of the bee, which is merely 

 a noise created by the vibration of the wings ; nor the 

 shrill sound of the cricket, which is caused by the friction 

 of his legs against the wing ; nor the shriek of the locust, 

 produced by the resonance of his cymbals, when put in vi- 

 bration by the opening and closing of the wings. 



122. Consequently, were the mammals, the birds and the 

 frogs, to be struck out of existence, the whole Animal King- 

 dom would be dumb. It is difficult for us, living in the 

 midst of the thousand various sounds which strike our ear 

 from all sides, to conceive of such a state. Yet, such a state 

 did prevail for thousands of ages, on the surface of our globe, 

 when the watery world alone was inhabited, and before man, 

 the birds, and the mammals were called into being. 



123. In man and the mammals, the voice is formed in an 

 organ called the larynx, situated at the upper part of the 

 windpipe, below the bone of the tongue (a). 



The human larynx, the part called Adam's NJ // 



apple, is composed of several cartilaginous 

 pieces, called the thyroid cartilage (&), the b- 

 cricoid cartilage (c), and the small aryte- 

 noid cartilages. Within these, are found two 

 large folds of elastic substance, known by the 

 name of the vocal cords (w). Two other Fig. 22. 

 analogous folds, the superior ligaments of the glottis (ri), 

 are situated a little above the preceding. The glottis (o), 

 is the space between these four folds. The arrangement of 

 the vocal cords, and of the interior of the glottis in man, is 

 indicated by dotted lines in Fig. 22. 



124. The mechanism of the voice is as follows : the air, 

 on its way to the lungs, passes the vocal cords. So long as 

 these are in repose, no sound is produced ; but the moment 

 they are put upon the stretch, they oppose an obstacle to the 

 current of air, and it cannot pass without causing them to 



4* 



