a considerable amount of _sa-li'va_, (spittle.) This fluid is
furnished by the salivary glands, situated in the vicinity of the
mouth. The saliva moistens and softens the food, so that, when carried
into the pharynx. it is passed, with ease, through the oesophagus into the
stomach.

262. When the food has been properly masticated, (and in rapid eaters
when it is not,) the soft palate is raised from the base of the tongue
backward, so as to close the posterior opening through the nostrils.
By a movement of the muscles of the tongue, cheeks, and floor of the
mouth, simultaneous with that of the soft palate, the food is pressed
into the upper part of the pharynx.

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259-272. _Give the physiology of the digestive organs._ 259. What is
necessary before food can nourish the body? 260. Describe how
mastication is performed. 261. Of what use is the saliva in the
process of mastication? 262. How is the food pressed into the
pharynx?

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263. When in the pharynx, the food and drink are prevented from
passing into the trachea by a simple valve-like arrangement, called
the _ep-i-glot'tis_. The ordinary position of this little organ is
perpendicular, so as not to obstruct the passage of air into the
lungs; but in the act of swallowing, it is brought directly over the
opening of the trachea, called the _glot'tis_. The food, being forced
backward, passes rapidly over the epiglottis into the oesophagus,
where the circular band of muscular fibres above, contracts and forces
the food to the next lower band. Each band relaxes and contracts
successively, and thus presses the alimentary ball downward and onward
to the stomach.[8]

[8] The process of deglutition may be comprehended by analyzing the
operation of swallowing food or saliva.

_Observation._ If air is inhaled when the food or drink is passing
over the glottis, some portions of it may be carried into the larynx
or trachea. This produces violent spasmodic coughing, and most
generally occurs when an attempt is made to speak while masticating
food; therefore, never talk when the mouth contains food.

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263. When the food is in the pharynx, how is it prevented from passing
into the trachea, or windpipe? Describe how it is passed into the
stomach? Give the observation. 264. Describe how the food in the
stomach is converted into chyme.

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264. When the food re