e atmosphere, and give off carbonic acid; while plants take up
the carbonic acid, and restore to animals the oxygen, thus affording
an admirable example of the principle of compensation in nature.

14. But the decisive distinctions between animals and plants are
_sensation_ and _voluntary motion_, the power of acquiring a knowledge
of external objects through the senses, and the ability to move from
place to place at will. These are the characteristics which, in their
fullest development in man, show intellect and reasoning powers, and
thereby in a greater degree exhibit to us the wisdom and goodness of
the Creator.

-=-=-=-=-=-=-=-=-=-=-=-=

11. What is said of the individuality of organized and inorganized
bodies? What is closely associated with this? 12. Give a distinction
between animals and plants as regards growth. The food of animals and
plants. What is said in respect to size? 13. What important
distinction in the effects of respiration of animals and plants? 14.
What are the decisive distinctions between animals and plants?

-=-=-=-=-=-=-=-=-=-=-=-=

15. DISEASE, which consists in an unnatural condition of the bodily
organs, is in most cases under the control of fixed laws, which we are
capable of understanding and obeying. Nor do diseases come by chance;
they are penalties for violating physical laws. If we carelessly cut
or bruise our flesh, pain and soreness follow, to induce us to be more
careful in the future; or, if we take improper food into the stomach,
we are warned, perhaps immediately by a friendly pain, that we have
violated an organic law.

16. Sometimes, however, the penalty does not directly follow the sin,
and it requires great physiological knowledge to be able to trace the
effect to its true cause. If we possess good constitutions, we are
responsible for most of our sickness; and bad constitutions, or
hereditary diseases, are but the results of the same great law,--the
iniquities of the parents being visited on the children. In this view
of the subject, how important is the study of physiology and hygiene!
For how can we expect to obey laws which we do not understand?

-=-=-=-=-=-=-=-=-=-=-=-=

15. What is said of disease? 16. Why is the study of physiology and
hygiene important?

-=-=-=-=-=-=-=-=-=-=-=-=

CHAPTER II.

STRUCTURE OF MAN,

17. In the structure of the human body, there is a union of fluids and
solids. These are essentially the same, for the one is