406 MR. YOUATx’b VETERINARY LECTURES. 
chest is that which we want in the animal of speed—the deep 
as w'ell as the broad chest—always capacious for the purpose of 
muscular strength, and becoming considerably more so when 
arterialized blood is more rapidly expended in quick progression. 
We cannot enlarge the capacity of a circle ; and if more blood is 
to be furnished, that which cannot be done bv increase of 
surface must be accomplished by frequency of action. There¬ 
fore it is that all our heavy draught-horses are thick-winded. It 
is no detriment to them, for their w^ork is slow ; or rather it is an 
advantage to them, for the circular chest, ahvays at its greatest 
capacity, enables them to acquire that weight which it is so 
advantageous for them to throw into the collar. 
Broken Wbid. 
Peculiar Breathing. —This is immediately recognizable by the 
manner of breathing. The inspiration is performed in somewhat 
less than the natural time, and with an increased degree of 
labour: but the expiration has a peculiar difficulty accompany¬ 
ing it: it is accomplished by a double effort, in the first of which, 
as IMr. Blaine has w’ellexplained it, “the usual muscles operate ; 
and in the other the auxiliary muscles, particularly the abdomi¬ 
nal, are put on the stretch to complete the expulsion more per¬ 
fectly, and, that being done, the flank falls, or the abdominal 
muscles relax with a kind of jerk or spasm.” 
An aggravated Degree of Thick Wind. —This may proceed 
from unusually extensive induration or hepatization of the lungs, 
or thickenino' of the bronchial membrane, renderingr it a work of 
labour to accomplish the expulsion of the air, and requiring ano¬ 
ther set of muscles to be gradually associated in the act. 
Different Theories of Broken Wind. —The most frequent cause 
or accompaniment of this breathing is an emphysematous state 
of the lungs. This, although not precisely a doctrine of modem 
date in veterinary pathology, has only lately been generally 
received. Some of the Greek Hippiatrists maintained that it 
proceeded from ulceration of the lungs, which had been obstructed 
and filled with dust; and others of them, that it was to be attri¬ 
buted to rupture of the lungs, from the concussion they expe¬ 
rienced in violent cough. Vegetius attributed it to the dryness 
of the lung, and the diminution of its volume. The Spanish vete¬ 
rinarians believed' that it arose from the bad quality of the blood, 
and the afflux of humours to the lungs ; and also a morbid con¬ 
traction of the bronchial tubes. The Italians seemed to refer it 
to ulceration and rupture of the lungs. M. Demoussy traced it 
to diminution of the calibre, both of the air-cells and the bron¬ 
chial tubes, from an aneurismatic varicose state of the vessels of 
