e the opening, having neither anticipation of an early call for
the admission of necessary nutriment, nor an instinctive desire to shut
out anything that may be indigestible or undesirable, are now in their
normal condition of peaceful, moderate contraction; the face has a
comfortable, well-fed, wholesome look. On the other hand, let the
digestive juices fail to do their duty properly, or the swarms of
bacteria pets which we keep in our food-canals get beyond control; or if
for any other reason the tissues be kept from getting their proper
supply of nourishment from the food-canal, the state of affairs is
quickly revealed in the mouth mirror. Those muscles which open the
mouth, instead of resting peacefully in the consciousness of duty well
done, are in a state of perpetual fidget, twitching, pulling, wondering
whether they ought not to open the portal for the entrance of new
supplies of material, since the tissues are crying for food.

As the strongest of these are those which pull the corners of the mouth
outward and downward, the resultant expression is one of depression,
with downward-curving angles to the mouth. The eyes, and even the
nostrils, sympathetically follow suit, and we have that countenance
which, by the cartoonist's well-known trick, can be produced by the
alteration of one pair of lines, those at the angles of the mouth,
turning a smiling countenance into a weeping one. On the other hand, if
all these processes of nutrition and absorption are proceeding as they
should, they are accompanied by mild sensations of comfort which,
although they no longer reach our consciousness, reveal themselves in
the mouth-opening muscles, and they gently contract upward and outward,
in pleasurable anticipation of the next intake, and we get the grin or
the smile.

If, on the other hand, these digestive disturbances be accompanied by
pain, then another shading appears on our magic mirror, and that is a
curious contraction of the mouth, with distortion of the lines
surrounding it, so violent in some cases as positively to whiten the
lips or produce lines of paleness along the course of the muscles. This
is the set or twisted mouth of agony, and is due to a curious
transference and reflex on this order: that inasmuch as the last food
which entered the alimentary canal seems to have caused this disturbance
and pain, no more will be allowed to enter it at present under any
conditions. And as our alimentary instincts are the