420 Mr. Bell’s experiments on the structure 
the inference, that the two sets of nerves distributed to the 
face have distinct functions ; even this must prove useful both 
to the surgeon and physician. To the surgeon it must be 
useful, in performing operations on the face, as well as in ob- 
serving the symptoms of disease ; but especially to the phy- 
sician must these facts be important ; he will be better able to 
distinguish between that paralysis which proceeds from the 
brain, and that partial affection of the muscles of the face, 
when, from a less alarming cause, they have lost the controul- 
ing influence of the respiratory nerve. 
Cases of this partial paralysis must be familiar to every 
medical observer. It is very frequent for young people to 
have what is vulgarly called a blight ; by which is meant, a 
slight palsy of the muscles on one side of the face, and which 
the physician knows is not formidable. Inflammations of 
glands seated behind the angle of the jaw will sometimes 
produce this. All such affections of the respiratory nerve 
will now be more easily detected ; the patient has a command 
over the muscles of the face, he can close the lips, and the 
features are duly balanced ; but the slightest smile is immedi- 
ately attended with distortion, and in laughing and crying 
the paralysis becomes quite distinct. 
The knowledge of the sources of expression teaches us to 
be more minute observers. The author had lately to watch 
the breathing of an infant which had been several times re- 
stored from a state of insensibility. At length the general 
powers fell low without any returning fit ; insensibility and 
loss of motion stole over the frame ; all but the actions excited 
by the respiratory nerves ceased ; then each act of respiration 
was attended with a twitching of the muscles of the ala nasi , 
