ON PRESSURE AS A CAUSE OF ROARING. 
523 
On exposing the trachea, for the purpose of examining some 
very minute threads given off by the recurrent nerves in their 
passage up the neck, I perceived that one of the lymphatic gan¬ 
glions, situated at the lower part of the trachea, about four or 
five inches from its entrance into the thorax, was much enlarged, 
and of a degree of hardness approaching to that of cartilage. 
The cellular membrane surrounding it had become indurated, 
and tended to increase the size of the tumour. The recurrent 
nerve of the same side was involved in this mass, which pre¬ 
sented exactly the same appearance as the scirrhous glands 
which are frequently found in the deep-seated regions of human 
subjects who have fallen victims to scrofulous disease. 
“ That part of the recurrent nerve situated between the tume¬ 
fied gland and the larynx did not at all resemble its fellow on 
the opposite side. It was much shrunken, and its nervous fibril- 
las could scarcely be detected. All the laryngeal muscles which 
were supplied with filaments from this nerve were so completely 
atrophied that it was with difficulty they could be recognized 
as muscular structure, even in its most degenerate state. The 
glottal opening was greatly distorted, the border of the right ary¬ 
tenoid cartilage being partially drawn over it. It appears very 
evident, that, in this case, the cause of the atrophy is clearly 
demonstrated by the fact of the recurrent nerve having been 
compressed by the scrofulous (perhaps I am wrong in using this 
term) gland, and thus being destroyed as a conductor of nervous 
influence to the muscles of the larynx. It is well known that 
when the motor nerves going to a muscle cease, from being 
either diseased or divided, to transmit to it that stimulus which 
is necessary for its contraction, atrophy is the inevitable con¬ 
sequence. 
‘‘ I should not be positive in my opinion relative to the com¬ 
pression of the nerve by the enlarged lymphatic gland being, in 
the present instance, the cause of the structural alteration of 
the laryngeal muscles, were I not enabled to produce similar 
effects by the simple division of the same nerve. I have many 
times divided the recurrents in the horse, the ass, the dog, and 
other animals, and have invariably observed the same eft’ects, 
although frequently modified in degree. In the horse, ass, and 
mule, it causes roaring; in the dog and cat, a peculiar alteration 
of voice. The alteration in the voices of the different animals 
experimented upon is caused by a paralysis of the dilating mus¬ 
cles of the larynx, resulting from the interception of the nervous 
communication between them and the medulla oblongata by 
the division of the grand conductor, the nerve itself. 
If, instead of dividing one recurrent only, we divide both. 
