paper in contact with ink, noting the passage of the liquid into the
crayon or the paper. Show how absorption from the food canal differs from
this kind of absorption.

Show by a diagram similar to Fig. 77 the two routes by which the foods
pass from the alimentary canal into the blood stream.




CHAPTER XII - ENERGY SUPPLY OF THE BODY


If one stops taking food, it becomes difficult after a time for him to
move about and to keep warm. These results show that food has some
relation to the energy of the body, for motion and heat are forms of
energy. The relation of oxygen to the supply of energy has already been
discussed (Chapter VIII). We are now to inquire more fully into the energy
supply of the body, and to consider those conditions which make necessary
the introduction of both food and oxygen for this purpose.

*Kinds of Bodily Energy.*—The healthy body has at any time a considerable
amount of _potential_, or reserve, energy,—energy which it is not using at
the time, but which it is able to use as its needs require. When put to
use, this energy is converted into such forms of _kinetic_ energy(69) as
are indicated by the different kinds of bodily power. These are as
follows:

1. _Power of Motion._—The body can move itself from place to place and it
can give motion to things about it.