RESPIRATION. 
587 
minislied circulation of air in one part of the lungs, and a conse- 
quent increase in the other. The natural and healthy murmur 
may be exceedingly weak or entirely absent in one part of the lung, 
while it is augmented in another. This exalted respiratory mur- 
mur, in all its modifications and grades of intensity, may be either 
free and clear, or attended by additional sounds termed rales or 
rattles. The most frequent of these latter phenomena in horses 
are the mucous and the sonorous rales ; next, the crepitating 
sound. There is another rale, described by authors, termed the 
sibilant or hissing, but this sound I do not recollect to have ob- 
served. Probably the other sounds in the chests of horses are 
too loud for the development of this rale. The three first-named 
rales are useful to the veterinary surgeon, and assist very 
materially his diagnosis. They are readily described : — first, the 
mucous rale is a bubbling of frothy fluid, so common and fresh 
in the memory of all who have ever stood near to a horse with 
sputa in the trachea and large bronchial tubes, as to require no 
illustration. The sonorous rale is invariably present in some 
affections of the lungs, and is readily observed when the chest is 
auscultated : it resembles the snoring of human sleep, a cavern- 
ous murmur ; in some cases it likens the cooing of the wood- 
pigeon, and in others the whining of a small dog, or a kind of 
wheezing. The crepitating rattle is best compared to the sound 
produced by rubbing a lock of hair between the thumb and finger 
close to the ear. Some authors have given elaborate illustrations 
of the various sounds heard within the chest during the existence 
of disease, a theorising in which they bewilder themselves, and 
puzzle those who attempt their practical discovery. The diseases 
of the chest affecting the movements of respiration are, bron- 
chitis, pneumonia, pleurisy, thoracic effusion, emphysema of the 
lungs, tuberculated lungs, and some affections of the heart. 
In the early stage of bronchitis the respiration is frequent, ac- 
companied by exalted murmur: as the disease advances the 
breathing becomes quick, then accelerated. It may exceed the 
pulse in rapidity, and the mucous rale sets in. These changes 
are soon succeeded by irregular respiration, the inspiration longest 
of duration. Occasionally the movement of the chest is incom- 
plete, and then the breathing is difficult, and the rale sonorous 
and powerful. The resonance of the trachea and large bronchi is 
generally dry during the first and second days of the case in the 
true or sthenic form of the disease. In the asthenic, the re- 
spiration at the onset is sometimes rare or slower than ordinary, 
and deeper, and, but for this large movement, would be pro- 
nounced undisturbed, and although in this kind of bronchitis, as 
in the sthenic, the murmur is sonorous, it early becomes 
