ll be properly performed, no
acid will be produced to interrupt these functions, and the muscles and
bones will grow together in just proportions.

CAROLINE.

I have often heard the rickets attributed to bad nursing, but I never
could have guessed what connection there was between exercise and the
formation of the bones.

MRS. B.

Exercise is generally beneficial to all the animal functions. If man is
destined to labour for his subsistence, the bread which he earns is
scarcely more essential to his health and preservation than the
exertions by which he obtains it. Those whom the gifts of fortune have
placed above the necessity of bodily labour are compelled to take
exercise in some mode or other, and when they cannot convert it into an
amusement, they must submit to it as a task, or their health will soon
experience the effects of their indolence.

EMILY.

That will never be my case: for exercise, unless it becomes fatigue,
always gives me pleasure; and, so far from being a task, is to me a
source of daily enjoyment. I often think what a blessing it is, that
exercise, which is so conducive to health, should be so delightful;
whilst fatigue, which is rather hurtful, instead of pleasure, occasions
painful sensations. So that fatigue, no doubt, was intended to moderate
our bodily exertions, as satiety puts a limit to our appetites.

MRS. B.

Certainly. --But let us not deviate too far from our subject. --The
bones are connected together by ligaments, which consist of a white
thick flexible substance, adhering to their extremities, so far as to
secure the joints firmly, though without impeding their motion. And the
joints are moreover covered by a solid, smooth, elastic, white
substance, called _cartilage_, the use of which is to allow, by its
smoothness and elasticity, the bones to slide easily over one another,
so that the joints may perform their office without difficulty or
detriment.

Over the bones the _muscles_ are placed; they consist of bundles of
fibres which terminate in a kind of string, or ligament, by which they
are fastened to the bones. The muscles are the organs of motion; by
their power of dilatation and contraction they put into action the
bones, which act as levers, in all the motions of the body, and form the
solid support of its various parts. The muscles are of various degrees
of strength or consistence in different species of animals. The
mammiferous tribe, or those that suckle their you