formation of any plant or animal tissue. The other three elements,
carbon, hydrogen, and oxygen, go to make up the carbohydrates; in fact,
it is from the names of these three elements that the term carbohydrate
is derived. The carbohydrates include the starches and sugars that are
used and eaten in so many forms, and these contain the three elements
mentioned, the hydrogen and oxygen contained in them being in the
proportion that produces water. Thus, as will readily be seen, by
separating the name into its parts--_carbo_ (carbon) and _hydrate_
(hydrogen and oxygen in the proportion of two parts of hydrogen and one
of oxygen, that is, in the form of water)--carbohydrate is simply carbon
united with water. While the facts just brought out have much to do with
food economy, they are of interest here chiefly because they help to
make clear the term carbohydrate, which, as will be admitted, is the
only correct name for the food substance it represents.

18. STARCH, one of the chief forms of carbohydrates, is found in only
the vegetable kingdom. It is present in large quantities in the grains
and in potatoes; in fact, nearly all vegetables contain large or small
amounts of it. It is stored in the plant in the form of granules that
lie within the plant cells.

Cooking applied to starch changes it into a form that is digestible.
Moist heat cooks the granules until they expand and burst and thus
thicken the mass. Dry heat changes starch first into a soluble form and
finally into what is called _dextrine_, this being the intermediate step
in the changing of starch into sugar.

19. SUGAR, another important form of carbohydrate, is mainly of
vegetable origin, except that which is found in milk and called
_lactose_. This, together with the fat found in milk, supplies the child