s grow only by additions to their surfaces.

9. "Organized bodies always present a combination of both solids and
fluids;--of solids, differing in character and properties, arranged
into organs, and these endowed with functional powers, and so
associated as to form of the whole a single system;--and of fluids,
contained in these organs, and holding such relation to the solids
that the existence, nature, and properties of both mutually and
necessarily depend on each other."

10. Another characteristic is, that organic substances have a _certain
order of parts_. For example, plants possess organs to gain
nourishment from the soil and atmosphere, and the power to give
strength and increase to all their parts. And animals need not only a
digesting and circulating apparatus, but organs for breathing, a
nervous system, &c.

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6. Define inorganic bodies. 7. What is said of the difference, in
general, between organic and inorganic bodies? 8. What of the growth
of organic and inorganic bodies? 9. What do organized bodies always
present? 10. Give another characteristic of organized substances.

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11. _Individuality_ is an important characteristic. For instance, a
large rock may be broken into a number of smaller pieces, and yet
every fragment will be rock; but if an organic substance be separated
into two or more divisions, neither of them can be considered an
individual. Closely associated with this is the power of _life_, or
_vitality_, which is the most distinguishing characteristic of organic
structure; since we find nothing similar to this in the inorganic
creation.

12. _The distinction between plants and animals_ is also of much
importance. _Animals grow proportionally in all directions_, while
plants grow upwards and downwards from a collet only. The _food_ of
animals is _organic_, while that of plants is _inorganic_; the latter
feeding entirely upon the elements of the soil and atmosphere, while
the former subsist upon the products of the animal and vegetable
kingdoms. The size of the vegetable is in most cases limited only by
the duration of existence, as a tree continues to put forth new
branches during each period of its life, while the animal, at a
certain time of life, attains the average size of its species.

13. One of the most important distinctions between animals and plants,
is _the different effects of respiration_. Animals consume the oxygen
of th