690 DISEASES OF THE .RESPIRATORY ORGANS. 
on account of the very decided character of the noise made 
by the animal in the field. The seller, who had himself 
ridden the horse for some time, having formed a different 
opinion about the matter, sent the animal to be examined. 
On submitting him to the usual test, a very loud, roaring 
sound was emitted during a canter across a ploughed field, 
it presently, however, ceased, the animal still continuing 
the pace; then again it occurred, and again ceased when the 
horse was compelled to gallop. 
Considerable time was devoted to the examination on more 
than one occasion, in order to ascertain if possible, whether 
the sound was in any way connected with a diseased condition 
of the respiratory organs. And the result was the establish¬ 
ment of a conviction of the animaFs soundness. 
The noise emitted could not be distinguished from that 
produced by a very bad i( roarerbut there was this very 
important difference in the circumstances under which it oc¬ 
curred ; viz. it was entirely independent of pace. Sometimes 
the horse would gallop half through a long run without 
giving utterance to the least noise; then again during a 
canter or quiet trot, the sound would suddenly become 
audible; and on several occasions it was produced in the 
course of a walk; but usually the animal would start off in 
a canter, roaring loudly for a few seconds, then breathe quite 
calmly for some time, and again indulge in a repetition of the 
noise, and again discontinue it according to his fancy; 
although it happened occasionally in his adverse mood he 
would sustain the character of an inveterate “ roarer ” during 
the whole time he was in the field, whether walking, trotting, 
or galloping. 
In this very remarkable case the opinion sent back with 
the animal, was to the effect that the “ roaring ” was a vo¬ 
luntary act, unconnected with disease of the respiratory 
organs, and that consequently the horse was not unsound. 
It is worthy of remark, that all voluntary sounds seem to be 
produced during the expiration, just as all vocal sounds are 
produced naturally, while on the other hand, abnormal sounds 
invariably occur during inspiration, not necessarily being 
confined to that act, as they may sometimes be distinguished 
during expiration also; but the sounds voluntarily emitted 
have always been audible, so far as we have observe them, 
only during expiration. 
Many varieties of sounds belonging to the voluntary class, 
will be noticed in different animals; some evidently are pro¬ 
duced by movements of the nostrils, others seem to arise 
from some action of the velum palati; and many, doubtless, 
