and junctions of the nerves. 
401 
sary to give an illustration of the sense in which the term is 
intended to be employed. When a post-horse has run its 
stage, and the circulation is hurried and the respiration ex- 
cited, what is his condition ? Does he breathe with his ribs 
only ; with the muscles which raise and depress the chest ? 
No. The flanks are in violent action ; the neck as well as the 
chest is in powerful excitement ; the nostrils as well as the 
throat keep time with the motion of the chest. So if a 
man be excited by exercise or passion, or by whatever acce- 
lerates the pulse, the respiratory action is extended and en- 
creased ; and, instead of the gentle and scarcely perceptible 
motion of the chest, as in common breathing, the shoul- 
ders are raised at each inspiration, the muscles of the throat 
and neck are violently drawn, and the lips and nostrils move 
in time with the general action ; and if he does not breathe 
through the mouth, the nostrils expand, and fall in time 
with the rising and falling of the chest ; and that apparatus 
of cartilages and muscles of the nose (which are as curious 
as the mechanism of the chest, and which are for expanding 
these air tubes) are as regularly in action as the levator and 
depressor muscles of the ribs. 
It is quite obvious, that some hundred muscles thus em- 
ployed in the act of breathing, or in the common actions of 
coughing, sneezing, speaking, and singing, cannot be associ- 
ated without cords of connection or affinity, which combine 
them in the performance of these actions : the nerves which 
serve this purpose I call respiratory nerves. 
