n of animal
matter.

CAROLINE.

Animal compounds contain, then, four fundamental principles; oxygen,
hydrogen, carbon, and nitrogen?

MRS. B.

Yes; and these form the immediate materials of animals, which are
_gelatine_, _albumen_, and _fibrine_.

EMILY.

Are those all? I am surprised that animals should be composed of fewer
kinds of materials than vegetables; for they appear much more
complicated in their organisation.

MRS. B.

Their organisation is certainly more perfect and intricate, and the
ingredients that occasionally enter into their composition are more
numerous. But notwithstanding the wonderful variety observable in the
texture of the animal organs, we find that the original compounds, from
which all the varieties of animal matter are derived, may be reduced to
the three heads just mentioned. Animal substances being the most
complicated of all natural compounds, are most easily susceptible of
decomposition, as the scale of attractions increases in proportion to
the number of constituent principles. Their analysis is, however, both
difficult and imperfect; for as they cannot be examined in their living
state, and are liable to alteration immediately after death, it is
probable that, when submitted to the investigation of a chemist, they
are always more or less altered in their combinations and properties,
from what they were, whilst they made part of the living animal.

EMILY.

The mere diminution of temperature, which they experience by the
privation of animal heat, must, I should suppose, be sufficient to
derange the order of attractions that existed during life.

MRS. B.

That is one of the causes, no doubt: but there are many other
circumstances which prevent us from studying the nature of living animal
substances. We must therefore, in a considerable degree, confine our
researches to the phenomena of these compounds in their inanimate state.

These three kinds of animal matter, gelatine, albumen, and fibrine, form
the basis of all the various parts of the animal system; either solid,
as the _skin_, _flesh_, _nerves_, _membranes_, _cartilages_, and
_bones_; or fluid, as _blood_, _chyle_, _milk_, _mucus_, the _gastric_
and _pancreatic juices_, _bile_, _perspiration_, _saliva_, _tears_, &c.

CAROLINE.

Is it not surprising that so great a variety of substances, and so
different in their nature, should yet all arise from so few materials,
and from the same original elements?

MRS. B.