ON ROARING. 
7 
same, and its disposition the same, as in the former case ; only in¬ 
stead of the lymph being effused into the interstices of the mem¬ 
brane, and thickening its substance, it is poured forth upon its sur¬ 
face, where it assumes any form chance or circumstances may 
happen to give it, and, in the end, becomes organized, and part of 
the pipe itself, or rather of the membrane. 
In the veterinary museum formerly belonging to my father is a preparation 
in which the muscle has been displaced by the formation of a cross-band of 
coagulable lymph between it and the posterior part of the tube, by which the 
interspace is divided into two passages, one large enough to admit a walnut, 
the other a hazel nut. The horse it was taken from breathed with labour and 
exertion, and, even when but moderately exercised, roared aloud. 
Ossification of the Larynx, by which is meant the entire 
or partial conversion of its substance into bone, a change peculiar 
to aged horses, may exist either as a cause or a concomitant of 
roaring. The parts commonly found thus converted are the thyroid 
cartilages ; though the others, at a later date, may participate in the 
change. It seems to be the result of some chronic inflammatory 
action excited in the cartilages; and this I feel inclined rather to 
ascribe to the injurious constraint to which the larynx is so re¬ 
peatedly subjected, than to any of the causes which give rise to it 
in the membrane. We occasionally meet with partial, but rarely 
with entire, osseous conversion of the rings of the windpipe; nor 
do we often see bony accretion of them one to another. 
Distortion of the Larynx and Windpipe, there is every 
reason for believing, is a fruitful source of this vexatious disorder. 
Dissection is every day adding to the instances of it; and when 
we come to meditate upon the notorious fact, that 
Harness-horses constitute a large Class of Roarers, 
we shall probably regard these views as well founded. When 
we look around us as we pass through the streets of London, and 
count the numbers of fine high-spirited horses there are in car¬ 
riages, waiting for hours and hours together for their masters and 
mistresses, and all the while reined up with their necks crooked in 
a form unnatural, and constrained and painful even to behold, 
much more to be borne, as is sufficiently manifest to any one from 
the continual jerks up and down of the suffering animals’ heads; 
and when we come to consider the constriction—nay, compression 
—that must all this while be exerted on the larynx, together with 
the forced bend that must in many take place in the upper portion 
of the windpipe, can we wonder that these parts should undergo 
distortion ? At first, it is true, the distortion is but a temporary 
grievance, the intervals of relaxation affording the parts, by nature 
highly elastic, an opportunity of recovering their shape and tone. 
Repeated and long-continued acts, however, of such violence gradu- 
