DISEASES OF THE RESPIRATORY ORGANS. 387 
same time, show the necessity of extreme caution in arriving 
at a decided conclusion. 
The tubes of the respiratory organs, during the passage of 
the air to and from them, are precisely in the position of the 
pipes of an organ, through which wind is driven by a certain 
mechanical arrangement; the sounds produced depend upon 
the calibre of the tubes, and also upon the character of the 
internal surface, any irregularity or flaw leading to an altera¬ 
tion in the tone. In whatever part of the length of the pipe 
the sound is originally produced, it always seems to occur at 
the point of exit; so in the case of a roarer or whistler, the 
noise is apparently in the nostrils, even though its origin 
should be in the bronchial tubes; this circumstance renders 
it impossible to decide upon the situation of the disturbing 
cause, even when the noise is most apparent, and prevents 
the application of remedies which might be effective in many 
cases could the exact situation of the disease be discovered. 
Numerous causes may at various times operate in the pro¬ 
duction of roaring or whistling. Anything interfering with 
the size of the tubes, any disturbance of the position of the 
cartilages of the larynx or trachea, deposits upon the mucous 
membrane in any part of its course, pressure from accidental 
tumours in any part from the commencement of the trachea 
to its termination, will, by modifying the vibrations of the 
atmosphere in the tube, alter the character of the sounds 
produced. 
In one case of an ox, a tumour in the pharynx pressing 
upon the side of the larynx occasioned the breathing to be 
carried on with a loud noise, which seemed to result from 
obstruction in the nostrils. Sometimes the breathing sud¬ 
denly becomes difficult, even to the extent of threatened 
suffocation, from which the animal is saved in a short time 
by the application of a powerful counter-irritant to the throat. 
Such instances are probably caused by partial closure of the 
glottal opening from spasmodic muscular action; this view is 
strengthened by the fact of the distressing symptoms being 
intermittent in some cases, while in others they suddenly 
cease altogether. Cases have recently occurred, in which the 
symptoms were so urgent that the performance of tracheotomy 
seemed to be the only plan for preserving the animals, but 
where counter-irritation proved so effective that the breathing 
became perfectly tranquil in a few hours. 
Organic disease of the muscles of the larynx, or constric¬ 
tion of any part of the cartilaginous structure, will of neces¬ 
sity produce permanent derangement of the respiratory 
function; recent disease will cause, probably, a temporary 
