THE LARYNX. 181 



has not eaten for two days. Use the lotion as before, and force him with 

 strong soup. 



15th. The dog has not voluntarily eaten, but is still forced with soup. 

 He is very costive. Give two grains of calomel and an equal quantity of 

 antimonial powder. 



18^. He has eaten a very little, but gets thinner and weaker. Continue 

 the lotion. 



21th. The ulcers are nearly healed, and the discharge of pus has 

 ceased. 



31 st. The mouth is clean, the gums are healed, and there is no longer 

 anything offensive about the dog. 



THE LARYNX 



is placed at the top of the windpipe, the exit from the lungs, and is also 

 connected with the Schneiderian membrane. At its upper part is the 

 epiglottis, the main guard against the passage of the food into the respir- 

 atory tubes, and, at the same time, of the instrument of the voice. It 

 consists of five cartilages united together by a ligamentous substance, and, 

 by distinct and perfect articulations, adapting itself to every change of 

 the respiratory process and the production of the voice. 



At the base is the cricoid cartilage, the support and bond of union of 

 the rest. Above are the arytenoid cartilages, resting on the chordae vocales 

 and influencing their action. The epiglottis is placed at the extremity of 

 the opening into the windpipe, with its back opposed to the pharynx, so 

 that when a pellet of food passes from the pharynx in its way to the oeso- 

 phagus, the epiglottis is applied over the glottis, and by this means closes 

 the aperture of the larynx, and prevents any portion of the food from 

 passing into it. The food having passed over the epiglottis, that cartilage, 

 from its elastic power, again rises and resumes its former situation. 



The thyroid cartilage envelopes and protects all the rest, and particu- 

 larly the lining membrane of the larynx, which vibrates from the impulse 

 of the air that passes. The vibrations spread in every direction until they 

 reach the delicate membrane of the tympanum of the ear. That membrane 

 responds to the motion without, and the vibration is carried on to the pulp 

 of the auditory nerve, deep in the recesses of the ear. The loudness of the 

 tone its acuteness or graveness depends on the force of the expired air 

 and the shortening or lengthening of the chord. Hence it is, that the tone 

 of the bark of the dog, or the neighing of the horse, depends so much on 

 the age or size of the animal. Thus we compare the shrill bark of the 

 puppy with the hoarse one of the adult dog ; the high-toned but sweet 

 music of the beagle with the fuller and lower cry of the fox-hound, and 

 the deep but melodious baying of the mastiff. I may, perhaps, be per- 

 mitted to add to these, the whinnying of the colt and the neighing of the 

 horse. 



Each animal has his peculiar and intelligible language. He who has 

 long lived among them will recognise the tone of delight at meeting, 

 rising into and terminating in a sharper sound ; the strong and elevated 

 tone when they are calling to or challenging each other at a distance ; 

 the short expression of anger the longer, deeper, hoarser tone of fear ; 

 the murmur almost as deep, but softer, of habitual attachment, and the 

 elevated yet melodious token of sudden recognition. I could carry on a. 



