THE LARYNX. 117 



ti seemingly compl .cated but really simple muscular apparatus. In 

 form it is an irregular oblong tube, exceedingly flexible, and capable 

 of adapting itself to all the natural or morbid changes of the respi- 

 ratory process, and to the production of all the various intonations 

 of sound or voice by which the animal expresses his emotions. It is 

 placed at the top of the windpipe, guards the exit from the lungs, and 

 prevents the passage of food into the respiratory canals. 



The Ericoid cartilage constitutes the base and support of this 

 organ, and serves in great measure as a bond of union to the rest. 



Placed above and resting upon this are the Arytenoid cartilages^ 

 prolongations of which rest upon the Chordae vacates, and influence 

 their action. The vocal ligaments take an oblique direction across 

 the larynx in the pig instead of a straight one, so that the angle is 

 at a considerable distance from the thyroid cartilage. They have 

 also a curious slanting direction, the anterior angle being depressed 

 and the arytenoid portion elevated. About the middle of the 

 chordae vocales, and immediately above them, are two sacculi, which 

 are generally supposed to be concerned in the act of grunting. From 

 the anterior parts of the larynx springs the epiglottis, a heart-shaped 

 cartilage placed at the extremity of the opening into the windpipe, 

 with its back opposed to the pharynx ; its use is this : food passing 

 from the pharynx in its way to the oesophagus presses down the 

 epiglottis, which, closing the aperture of the larynx, prevents any 

 portion of the food from entering it. As soon as the food has passed, 

 the elasticity of the epiglottis, assisted by that of the membrane at 

 its base, and still more by the power of the hyo-epiglottideus muscle, 

 enables that cartilage to rise up and resume its natural position. 



The thyroid cartilage envelops and protects all the rest, and 

 shields the lining membrane of the larynx, which vibrates under the 

 impulse communicated by the passage of the air, and gives the tone 

 or voice. 



In the larynx of the hog we find that beautiful adaptation of means 

 to the end. The space between the arytenoid cartilages is less, 

 comparatively speaking, than in the horse or dog, speed not being 

 required in swine. The epiglottis, too, is larger than in the ox, sheep, 

 or horse, and differently constructed ; it is more flexible, from the 

 cellular ligamentous substance at the base of it being looser ; and 

 from its increased size, and the curved direction of its edges, it not 

 only covers the opening into the windpipe, but in a manner embraces 

 the arytenoid cartilages when pressed down by the passage of food, 

 a formation admirably suited to an animal who is constantly plunging 

 his nose and muzzle into the mud or dirt, and who, by blowing into 

 his food in the peculiar way pigs are apt to do in order to stir up tho 

 sediment, would otherwise be constantly getting some irritating and 

 noxious matters into his windpipe. The inferior cornu of the thy 

 roid bone is comparatively more developed in the hog than in other 

 domesticated animals. 



