'598 



COMPARATIVE PHYSIOLOGY. 



The epiglottis, in so far as it has any effect, in all probability 

 modifies the voice in the direction of quality. 



Pathological.— Paralysis of 

 the laryngeal muscles, owing to 

 pressure on nerves and conse- 

 quent narrowing of the glottic 

 opening, explains " roaring " in 

 the horse, in certain instances 

 at all events. 



Comparative. — ^Much more 

 is known of the sounds emanat- 

 ing from the lower animals 

 than of the mechanisms by 

 which they are produced. This 

 applies, of course, especially to 

 such sounds as are not pro- 

 duced by external parts of the 

 body, it being very difficult to 

 investigate these experimental- 

 ly or to observe the animal 

 closely enough when produc- 

 ing the various vocal effects 

 naturally. 



All our domestic mammals 

 have a larynx, not as widely different from that of man as 

 might be supposed from the feeble range of their vocal powers. 

 There are structural differences in the larynx of the domestic 

 animals, some of which are more readily appreciated by the eye 

 than described. 



The false (superior) vocal bands are rudimentary or want- 

 ing in many mammals, including the horse, ass, etc. 



In ruminants the larynx is proportionately ill-developed ; 

 the glottis is short, the vocal bands rudimentary, and the ven- 

 tricles wanting. 



The larnyx of the pig is peculiar in that the ventricles are 

 deep, though their opening is only a narrow slit; there is, how- 

 ever, a large membranous sac below the epiglottis, which, 

 acting as a resonator, explains the great intensity of the voice 

 of this animal. 



The actual behavior of the vocal bands has been studied 

 experimentally in the dog when growling, barking, etc. And, 

 so far as it goes, this animal's mechanism of voice-production 



Fig 437 — Postero lateral view of the lar- 

 ynx of the horae (Ohauveau). 1, epi- 

 glottis ; 3, arytenoid cartilages ; 3, 

 ttiyroid cartilage; 4, aryteDoideus 

 muscle; 5, crico-arytenoideus latera- 

 lis; 6, thyro-arytenoideus; 7, crico- 

 arytenoideus posticus: 8, cnco-thjr- 

 roideus; 9, ligament between the cri- 

 coid cartilage and first ringof trachea ; 

 10. 11, infero-posterior extremities of 

 crico-thyroid cartilages. 



