RALES, sounds heard in the respiratory passages, due to certain modifications in the normal structure of the bronchi or alveoli, or both. that originate in the pleural cavity are distinguished as friction sounds. Riles are new sounds, not common to healthy lungs, and are created either in the bronchi, bronchioles, air-vesicles or pathological cavities. They are due to a number of causes, the most frequent of which are (1) the passage of air through narrowed bronchi, such narrowing being the result of inflammation of the mucous membrane or of muscular spasm, and (2) the passage of air through or by a certain amount of fluid, either mucus, pus, blood-serum or combinations of these. Riles of the first type are dry; those of the second are called wet. The dry riles are usually musical, and on plac ing the ear to the chest, where they are present, one hears either high-pitched whistling sounds, sibilant riles or low-pitched, blowing or sonor ous riles, depending on the source of the sound, whether finer or larger bronchi. Both
types may commingle. Such riles are common in asthma, in the chronic bronchitis of emphy sema and- in the early stages of a bronchitis, before the exudation of mucus has begun. The moist riles are ritually of two kinds: (1) very fine or subscrepitant riles, resembling in sound the rubbing of a lock of hair between the fingers, and (2) larger mucous riles. The former are common in various types of disease in which the air-vesicles are involved, broncho pneumonia, lobar pneumonia, tuberculous pneu monia, etc. They are due to congestion and the pouring out of blood-serum into the area. The most mucous, riles are present in bronchitis. They occur in the larger bronchi, or in cavities, and resemble the bubbling; and gurgling sounds of water in a pipe. It requires the trained ear of the physician to distinguish between the different varieties,' and much experience to be able to prejudge the significance of the riles after they are knit* •