PHYSIOLOGY OF MOVEMENT. 



761 



but the opening to them is narrow. The voice of the ass is characterized 

 by the fact that it commences in an inspiratory movement in the produc- 

 tion of a sound of high-pitch and it terminates in expiration in the 

 production of a deeper sound. 



The larynx of ruminants offers considerable differences to that of 

 solipedes. The glottis is short, and the vocal cords can scarcely be dis- 

 tinguished from the lining membrane of the larynx, and there are no 

 ventricles. The voice in ruminants is, -therefore, more imperfect than in 

 the horse, and consists of a 



sound of low pitch capable of B -* 



but little variation (Fig. 317). 



In the hog below the epi- 

 glottis is found a large, mem- 

 branous sack, which fulfills the 

 purpose of a resonator, greatly 



Fig. 316.— Larynx of the Horse 

 from Above and Behind. (Miiller.) 

 a a', thyroid cartilage ; 6 b, arytenoid car- 

 tilages; cc', arytenoid muscles; fl ell, aryepiglottic 

 foldB; e, epiglottis. 1 II, posterior crico-arytenoid 

 muscles; 2 21, oblique arytenoid muscles; 3 31, 

 superior thyro-arytenoid muscles; iJ,l, true vocal 

 cords ; 5, glottis ; 6, ventricles of larynx. 



Fig. 317.— Larynx and Hyoid Bone of Ox. 

 (Miiller.) 

 1, 2, 3. arms of the hyoid bone; 4. thyroid cartilage; 5, body 

 of the hyoid bone; 5' and 5". fork of the hyoid bone ; 6, arytenoid 

 cartilages ; 7, epiglottis ; 8, cricoid cartilage ; 9, posterior crico- 

 arytenoid muscles ; 10, trachea. 



strengthening the intensity of the voice and giving to it its peculiar 

 character. In the hog the inferior vocal cords are inserted into the 

 tracheal border of the tlryroid cartilage and the arytenoid cartilages 

 are fused together, the vocal cords are rudimentary, the ventricles are 

 deep and communicate with the interior of the larynx only b}- a narrow 

 slit. Two characters of sound may be produced by the hog, the one 

 of low pitch, a grunt, which is the habitual sound, while another of very- 

 high pitch is only produced when the animal is maltreated or excited. 

 In the dog the vocal cords are well developed, while the false vocal 



