586 
RESPIRATION. 
be added convulsive breathing: and the respiratory movements 
may be either thoracic or abdominal. Respiration is difficult 
when the large accessory muscles are called into action ; it is 
easy when their aid is not required. When the lungs on both 
sides of the chest act equally, or concur in extent and function, 
the respiration is complete; but when one side or division of the 
lungs or portion of the lung is partially suspended, the move- 
ment is then termed incomplete. When the muscles of respira- 
tion contract suddenly and with violence, the breathing is con- 
vulsive. Respiration is termed thoracic when the diaphragm 
takes no part in the expansion of the chest, it being effected en- 
tirely by the ribs and their particular muscles. When the ribs 
are passive and apparently fixed during inspiration, the dia- 
phragm alone accomplishing this purpose, respiration is said 
to be abdominal. Such are the external characters of respira- 
tion as observed in the motions of the chest: but there are 
other and important phenomena furnished by respiration inter- 
nally of the thorax, in the sounds recognised by the ear on its 
application to the trachea, bronchi, or walls of the chest, during 
the circulation of the atmospheric air in the lungs. 
The ingress and egress of air to and from the chest pro- 
duce a sound in the larynx, trachea, and bronchial ramifications, 
throughout the whole volume of the lungs, to which the very ex- 
plicit term respiratory murmur has been given and very generally 
accepted. It presents much variety in health, differing in power or 
intensity ; heard at all points of the thorax, but being much fainter 
in some parts than in others; depending on the vicinity of the 
large bronchial divisions, and the substance of the parietes of the 
chest at the point examined, and the frequency of the respiration. 
In the trachea and first division of the bronchi the sound is simi- 
lar to the faint blast of a pair of forge bellows. Within the lungs 
it is reduced to a distant murmur, presenting in different animals, 
from various circumstances, manifold grades of intensity. It is 
the changes in these natural sounds, the result of some lesion of 
the respiratory organs, which produce the pathological pheno- 
mena of auscultation ; and these must be added to the move- 
ments of the thorax, or the characters of respiration would other- 
wise be imperfectly constituted. The different sounds are de- 
signated by terms which are briefly explained. When the mur- 
mur of respiration is increased beyond the ordinary force of 
health, it is said to be puerile in the human subject; but this 
term is not applicable to quadrupeds, nor does it convey the kind of 
respiration intended to be represented. Puerile respiration com- 
prehends the natural phenomena of infants, while this noisy murmur 
in adults is an exaltation of the respiratory sound, the result of di- 
