ntain an astringent called tannin, which
gives the peculiar bitter taste to the infusions when steeped too long. In
cocoa, the fat known as cocoa butter amounts to fifty per cent.

121. Tea. It has been estimated that one-half of the human race now
use tea, either habitually or occasionally. Its use is a prolific source
of indigestion, palpitation of the heart, persistent wakefulness, and of
other disorders. When used at all it should be only in moderation. Persons
who cannot use it without feeling its hurtful effects, should leave it
alone. It should not be taken on an empty stomach, nor sipped after every
mouthful of food.

122. Coffee. Coffee often disturbs the rhythm of the heart and causes
palpitation. Taken at night, coffee often causes wakefulness. This effect
is so well known that it is often employed to prevent sleep. Immoderate
use of strong coffee may produce other toxic effects, such as muscular
tremors, nervous anxiety, sick-headache, palpitation, and various
uncomfortable feelings in the cardiac region. Some persons cannot drink
even a small amount of tea or coffee without these unpleasant effects.
These favorite beverages are unsuitable for young people.

123. Cocoa. The beverage known as cocoa comes from the seeds of the
cocoa-tree, which are roasted like the coffee berries to develop the
aroma. Chocolate is manufactured cocoa,--sugar and flavors being added to
the prepared seeds. Chocolate is a convenient and palatable form of highly
nutritious food. For those with whom tea and coffee disagree, it may be an
agreeable beverage. The large quantity of fat which it contains, however,
often causes it to be somewhat indigestible.

124. Alcoholic Beverages. There is a class of liquids which are
certainly not properly food or drink, but being so commonly used as
beverages, they seem to require special notice in this chapter. In view
of the great variety of alcoholic beverages, the prevalence of their
use, and the very remarkable deleterious effects they produce upon the
bodily organism, they imperatively demand our most careful attention, both
from a physiological and an hygienic point of view.

125. Nature of Alcohol. The ceaseless action of minute forms of plant
life, in bringing about the decomposition of the elaborated products of
organized plant or animal structures, will be described in more detail
(secs. 394-398).

All such work of vegetable organisms, whether going on in the moulding
cheese, in th