DISEASES OF THE EESPIRATORY ORGANS. 587 



and is altogether lost over the sixteenth. In the inferior part 

 of the chest it diminishes at the seventh, and is lost at the tentli 

 rib. On the left side it is mixed in the lower and anterior 

 regions, immediately behind the shoulder, with the sounds of 

 the heart. 



2. The Bronchial or Tubal sound resembles the blowing of air 

 quickly through a tube ; it is higher in pitch than the vesicular 

 murmur, and more rapidly evolved. It is nearly as prolonged 

 during inspiration as expiration, with a distinct interval between 

 the two. This sound is distinct over both the middle and upper 

 thirds of the chest ; loudest immediately behind the scapula 

 and caput magnum, or the nearer we can approach the ear to the 

 bifurcation of the trachea and larger bronchial tubes ; diminish- 

 ing in intensity to the twelfth rib, where it is superseded by the 

 vesicular, and entirely lost at about the seventeenth rib. It also 

 diminishes in intensity as it approaches the upper part of the 

 lower third of the chest, where it becomes lost in the vesicular 

 sound. The tubal sound becomes diagnostic of disease when it 

 is heard in the inferior portions of the chest. 



In the ox, the bronchial sound is heard much lower down in 

 the right side, owing to the large tube which passes to the 

 anterior lobe of the right lung. 



The true thoracic sounds are very often complicated with 

 abdominal rumblings or gurglings, due to the movement of food, 

 fluids, and gases within the alimentary canal ; these are loudest 

 in the posterior part of the chest, are irregular in their occm"- 

 rence, and bear no relationship to the respiratory movements. 

 A little practice will soon enable the student to distinguish 

 these from the respiratory sound. 



Percussion. — The sound obtained by percussing the healthy 

 chest is loudest over those parts where the bronchial sounds 

 are best heard, except indeed in those parts most thickly clad 

 with muscular tissue. On the left side the resonance is very 

 clear immediately behind the shoulder to the twelfth or thirteenth 

 rib, where it gradually diminishes. If the parts are here struck 

 forcibly, the intestinal resonance may be induced. 



Mr. Percivall has pointed out what may be easily verified in 

 practice, that the sound along the right superior region grows 

 louder from the posterior border of the shoulder to the last rib, 

 'ft-hilst on the left it gradually diminishes on the same line. 



