232 THE HUMAN BODY. 



The larynx is but slightly developed in early infancy, and 

 does not differ in its dimensions in the two sexes; and the 

 characteristics of the voice are the same also. From the t 

 third to the twelfth year this organ remains nearly stationary; 

 but about the fourteenth year it almost doubles in size in the 

 boy, and the voice takes a masculine character. This evolu- 

 tion is rapid, and is nearly accomplished in the course of a 

 year, though the larynx is not perfectly developed till the 

 twenty-fifth year. In girls it augments about a third in size. 

 The larynx, therefore, of an adult woman is smaller than that 

 of man, its angles are less prominent, and the glottis is 

 smaller. These differences are related to the characteristic 

 pitch, compass, and power, which distinguish the voice of 

 man from that of woman. 



In diaphragmatic respiration the larynx is immovable; but 

 when the expansion of the chest extends to the upper ribs, 

 the sternum, and the clavicle, two of the extrinsic muscles 

 of the larynx assisting in the elevation of the sternum, cause 

 by their contraction the descent of the larynx, to which they 

 are attached by their upper extremities. (See Respiration, 



P- 97-) . 



Physiology of the larynx, mechanism of the voice. Like most 

 physiological questions, that of the emission of the voice is 

 differently explained by writers on that subject. In order to 

 explain its functions, the larynx has been compared to dif- 

 ferent musical instruments. Gerdy thought "that we should 

 do better to endeavour to show that this instrument in man 

 has no resemblance to any one formed by art." This, doubt- 

 less, is true; the human larynx is as inimitable in its perfec- 

 tion as it is admirable in the results it produces; but, in 

 comparing the most ingenious machines of this character 

 that man has ever constructed, with the larynx, we do pre- 

 cisely what Gerdy recommends, for this is the surest means 

 of establishing its evident superiority. The analogy is besides 

 incontestable, in spite of the distance which separates an 

 inert mechanical production from a living organic apparatus, 

 and it is only by studying the formation of sounds in instru- 

 ments that we can, if not explain, at least seek to comprehend 

 their formation in the larynx. 



