438 DISEASES OF THE KESPIRATORY ORGANS. 



ence to the form or character of the tube, the extent to which 

 its cahbre is lessened by infiltration of the submucous struc- 

 ture, or the presence of plastic material on its surface. They 

 are of necessity of variable intensity or pitch, and are often 

 spoken of as — 



a. Large or Sonorous Rale, or Rhonchus. — This is essentially 

 a sound of the larger bronchi. It is of a low bass note, sub- 

 ject to much variation, the greater tones being in the larger 

 tubes. It is generally heard best at the lowest part of the 

 windpipe, at the anterior portion of the chest, or behind the 

 shoulder ; often of a vibratory character, as if the air were 

 playing over some dry adherent mucus, and is transient in its 

 existence, and of variable intensity. It is a frequent accom- 

 paniment of the early stages of bronchitis ; and if there exists 

 much infiltration of the submucous tissue, will be more likely 

 to be permanent ; it is heard during both expiration and 

 inspiration. Accompanying this sound we often observe the 

 sibilant or mucous rale in which the smaller tubes are in- 

 volved. 



h. Smaller Dry Sound, or Sibilant Rale. — This is a higher- 

 pitched whistling or wheezing sound, of varying duration, 

 heard during expiration and inspiration, but, unlike the larger 

 sound, better heard during the latter part of the respiratory 

 act. It seems to owe its existence to essentially the same 

 causes as the sonorous rale. It is characteristic of the earlier 

 or dry stages of bronchitis, and is best heard over the portions 

 of the lung-tissue where in health the vesicular sound is 

 loudest. When extensively distributed it constitutes a matter 

 of more serious import than the larger sound heard in con- 

 nection with the great tubes. 



2. Moist or Mucous Sounds or Rales. — These are the sounds 

 which in a general way we find following the dry in cases of 

 inflammation of the air-tubes. The impression conveyed to 

 the ear by these moist or humid rales is that of bubbles of air 

 passing through liquids, and in passing burstmg. The varia- 

 tions in the sound are connected with the character of these 

 air-bubbles and the fluid with which they mingle. 



Of these moist sounds we speak of at least three or four 

 variations. 



a. The Mucous Rale. — By this term is ordinarily understood 



