shment to the system consists in proper mastication, or chewing.
Food should be thoroughly masticated before it is taken into the
stomach. This is necessary in order to break it up and reduce it to a
sufficient degree of fineness for the efficient action of the gastric
juice. Besides, the action of chewing and the presence of nutrient food
constitute a healthful stimulus to the salivary glands, situated in the
mouth. By this means, also, the food not only becomes well masticated,
but has blended with it a proper amount of saliva, upon both of which
conditions the healthy action of the stomach depends. We have here
another illustration of the beneficence of the Creator, who has kindly
so arranged that the very act of mastication gratifies taste, the mouth
being the seat of this sensation. But if we disregard these benevolent
laws, and introduce unmasticated food into the stomach, the gastric
juice can act only upon its surface, and changes of a purely chemical
nature frequently commence in food thus swallowed before digestion can
take place. Hence frequently arise--and especially in children and
persons of delicate constitution--pains, nausea, and acidity, consequent
on the continued presence of undigested aliment in the stomach.

2. CHYMIFICATION.--As soon as food has been thoroughly masticated and
impregnated with saliva, it is ready for transmission to the stomach.
This interesting part of the process of digestion, called deglutition or
swallowing, is most easily and pleasantly performed, when the alimentary
morsel has been well masticated and properly softened, not by drink,
which should never be taken at this time, but by saliva. When the food
reaches the stomach, it is converted into a soft, pulpy mass, called
_chyme_; and the process by which this change is effected is called
_chymification_. This is the second principal step in digestion, and is
effected immediately by the action of the _gastric juice_. This powerful
solvent is secreted by the gastric glands, which are excited to action
by the presence of food in the stomach. In health, the gastric secretion
always bears a direct relation to the quantity of aliment required by
the system. If too much food is taken into the stomach, indigestion is
sure to follow, for the sufficient reason that the gastric juice is
unable to dissolve it. This is true even when food has been well
masticated; but it becomes strikingly apparent when a full meal has been
hastily swallow