80 DISEASES OF THE LUNGS. 



horse but indistinct resonance ; the sound is plainer in the adult, but 

 loudest of all in the old : a difference no doubt ascribable to the changes 

 the sinuses undergo with age. As the resonance of the nasal chambers is 

 diminished by the presence of polypi, or the accumulation of pus, so is that 

 of the sinuses by even but a small purulent collection. Purulent reple- 

 tion completely deadens sound. At the same time, percussion becomes 

 painful, and the frontal bone often convexed. 



The Larynx, in a state of health, yields but a faint sound to the ear. 

 Under disease, however, we may with Leblanc regard the anormal sounds 

 as consisting, — 1st. In a dry whistle^ which is the result of contraction, 

 either from confirmation or compression, or of physical or vital lesion of 

 the recurrent nerve. 2d. In a humid whistle, the consequence of a tumid 

 membrane covered with mucus, which is sometimes intermittent and 

 accompanied with a gurgling noise or mucous rale, as in acute laryngitis. 

 3d. In a rale, which may be either dry or humid, audible either at the 

 beginning or decline of laryngitic inflammation. 



The Windpipe yields but little to our listenings, unless it be at the 

 superior and inferior parts. At its entrance into the chest, in the normal 

 condition, is heard the sound of soft blowing, most prolonged during expi- 

 ration. This respiratory sound, which is occasioned by the air returning 

 from the bronchial tubes into the windpipe, we call, from its situation, 

 tracheo-hronchial respiration. Frequency of respiration increases it. 

 When liquids become effused into the bronchial tubes, the mucous rale is 

 heard ; and this is often accompanied by the sihilous rale and by the sonor- 

 ous rale. In case of effusion of blood into the tubes, the rale is spumous. 



The Thobax affords no information to the feel, except in the case of 

 pleurisy, and then the animal sensibly flinches from pressure sharply ap- 

 plied against the intervals of the ribs. Oxen will even moan from the 

 pain so occasioned. Neither admeasurement nor succussion of the chest 

 produces any satisfactory results. 



Percussion of the Thorax means striking or tapping its sides with a 

 view of judging, from the different sounds elicited, of the normal or anor- 

 mal condition of the organs within. The chest is said to resomid vfhen 

 the vibrations raised by the shock extend throughout the chest and the 

 contained viscera; on the contrary, when they appear confined to the 

 place struck, it is said not to resound, or that the sound is dtdl or dead. 

 The shock occasioning the vibration may be direct or indirect in its appli- 

 cation, it being in the latter case conveyed through some intermediate 

 body : hence the distinction between mediate and immediate percussion. 



In the practice of percussion, Leblanc makes use of a small iron 

 hammer and a wooden guard or shield, the latter covered with India- 

 rubber upon the surface to be applied to the chest. The sound thus pro- 

 duced exceeds that elicited by any soft body, such as the hand, against 

 the equally soft skin. Such an apparatus, however, is apt to raise two 



