orth observing.
Birds residing constantly in the atmosphere, surrounded by oxygen, and
respiring it in greater proportions than any other species of animals,
are endowed with a superior degree of muscular strength, whilst the
muscles of fish, on the contrary, are flaccid and oily; these animals
are comparatively feeble in their motions, and their temperature is
scarcely above that of the water in which they live. This is, in all
probability, owing to their imperfect respiration; the quantity of
hydrogen and carbon, that is in consequence accumulated in their bodies,
forms the oil which is so strongly characteristic of that species of
animals, and which relaxes and softens the small quantity of fibrine
which their muscles contain.

CAROLINE.

But, Mrs. B., there are some species of birds that frequent both
elements, as, for instance, ducks and other water fowl. Of what nature
is the flesh of these?

MRS. B.

Such birds, in general, make but little use of their wings; if they fly,
it is but feebly, and only to a short distance. Their flesh, too,
partakes of the oily nature, and even in taste sometimes resembles that
of fish. This is the case not only with the various kinds of water
fowls, but with all other amphibious animals, as the otter, the
crocodile, the lizard, &c.

CAROLINE.

And what is the reason that reptiles are so deficient in muscular
strength?

MRS. B.

It is because they usually live under ground, and seldom come into the
atmosphere. They have imperfect, and sometimes no discernible organs of
respiration; they partake therefore of the soft oily nature of fish;
indeed, many of them are amphibious, as frogs, toads, and snakes, and
very few of them find any difficulty in remaining a length of time under
water. Whilst, on the contrary, the insect tribe, that are so strong in
proportion to their size, and alert in their motions, partake of the
nature of birds, air being their peculiar element, and their organs of
respiration being comparatively larger than in other classes of animals.

I have now given you a short account of the principal animal functions.
However interesting the subject may appear to you, a fuller
investigation of it would, I fear, lead us too far from our object.

EMILY.

Yet I shall not quit it without much regret; for of all the branches of
chemistry, it is certainly the most curious and most interesting.

CAROLINE.

But, Mrs. B., I must remind you that you promised to giv