stimulus. The contractile power of the
muscular coat, and the free passage of the intestinal contents from the
stomach downward, are greatly aided by the constant but gentle agitation
which the whole digestive apparatus receives during the act of
breathing, and from exercise of every description. By free and deep
inhalations of air into the lungs, the diaphragm is depressed and the
bowels are pushed down. But when the air is thrown out from the lungs,
the diaphragm rises into the chest, and the bowels follow, being pressed
upward by the contractile power of the abdominal muscles. During
exercise, breathing is deeper and more free, which gives additional
pressure to the bowels from above. The abdominal muscular contraction is
also, in turn, more vigorous and extensive, and thus the motion is
returned from below. Persons that take little or no exercise, or who
allow the chest and bowels to be confined by tight clothing, lose this
natural stimulus, and frequently become subjects of immense suffering
from habits of costiveness. These should be removed if possible, and
they generally can be by a proper course of discipline. This should have
reference to both diet and exercise. Such articles of food should be
used as tend to keep open the bowels. This should be combined with the
free exercise of the lungs and the abdominal muscles. In addition to
these, there should be a determination to secure a natural evacuation of
the bowels at least once a day. This is regarded by physiologists
generally as essential to health. Efforts should be continued until the
habit is established. Some definite period should be fixed upon for this
purpose. Soon after breakfast is, on many accounts, generally
preferable.

TIME FOR MEALS.--Before passing from the subject of digestion, I will
submit a few thoughts in relation to the times for eating. It has
already been observed that _three or four hours_ are generally necessary
for the digestion of a simple meal. Usually, perhaps, a greater length
of time is required. It is also an established doctrine, based upon the
results of careful examination and experiment, that _the stomach
requires an interval of rest_, after the process of digestion is
finished, to enable it to recover its tone before it can again enter
upon the vigorous performance of its function. As a general rule, then,
_five or six hours should elapse between meals_. If the mode of life is
indolent, a greater time is required; if acti