ON ROARING. 
65 
Cj'ib-bitlng supposed to be a Cause of Roaring. —Connected 
witli this is the common notion that crib-biting is a cause of 
roaring. That is altogether erroneous. There is no possible 
connexion between the complaints : but one of the methods that 
used to be resorted to in order to cure crib-biting might be a 
cause of roaring, namely, the strap so tightly buckled round the 
upper part of the neck as to compress, and distort, and paralyze 
the larynx. 
The Absorption of the Muscles of the Larynx. —Here, gentle¬ 
men, is a very singular preparation. It is the larynx of a roarer. 
You perceive the muscles of the larynx on one side as large as 
usual, or even larger; on the other side they have dwindled away 
and almost vanished. There is a little distortion of the larynx here, 
but no twisting of it out of its place, so that the muscles of one 
side could not act, and were absorbed for want of use. How do 
we account for this ? Why, loss of muscular power, and conse¬ 
quent wasting of muscular substance, may be the result of the 
loss of nervous influence as well as the interposition of some me¬ 
chanical impediment to the action of the muscles, and the French 
have a theory to which specimens like this give an appearance 
of probability. 
Deficiency of Nervous Influence. —I must here recall your at¬ 
tention to what I stated in a former lecture of the source whence 
the muscles of the larynx derived their power. We threw these 
muscles into two classes, the dilators and the constrictors; they 
were both supplied with nervous influence from the par vagum, 
or eighth pair of nerves, one of the respiratory nerves of Sir 
Charles Bell, and the pneumo-gastric (a better name) of the 
French; but they were supplied from different branches of this 
nerve, the constrictors from the laryngeal branch, and the dila¬ 
tors from the recurrent nerve. French physiologists imagined, 
that if the pneumo-gastric nerve could be compressed at any 
part between the laryngeal and recurrent branches, the powder of 
the dilators would be taken away on that side, and the constric¬ 
tors acting on both sides, roaring, from the partial obliteration of 
the air-passage, would be the inevitable result. In conformity 
with this they have fancied that they have discovered, in horses 
that had been destroyed for roaring, little ganglions pressing 
upon the pneumo-gastric nerve at different parts of its course 
down the neck, and depriving the recurrent nerve on one side of 
its power. 
I am not aware that any English veterinarian has observed 
this, or indeed put himself in the way of observing it. It is a 
very ingenious theory, and deserves serious investigation. It is 
possible that the pressure of the collar, as well as that of the 
VOL. VI. I 
