enient (and indeed necessary)
to associate the sciences which deal with vitality and all its phenomena
under the common head of "biology"; and the biologists have come
to repudiate any blood-relationship with their foster-brothers, the
mineralogists.

Certain broad laws have a general application throughout both the animal
and the vegetable worlds, but the ground common to these kingdoms of
nature is not of very wide extent, and the multiplicity of details is so
great, that the student of living beings finds himself obliged to devote
his attention exclusively either to the one or the other. If he elects
to study plants, under any aspect, we know at once what to call him. He
is a botanist, and his science is botany. But if the investigation of
animal life be his choice, the name generally applied to him will vary
according to the kind of animals he studies, or the particular phenomena
of animal life to which he confines his attention. If the study of
man is his object, he is called an anatomist, or a physiologist, or an
ethnologist; but if he dissects animals, or examines into the mode in
which their functions are performed, he is a comparative anatomist or
comparative physiologist. If he turns his attention to fossil animals,
he is a palaeontologist. If his mind is more particularly directed
to the specific description, discrimination, classification, and
distribution of animals, he is termed a zoologist.

For the purpose of the present discourse, however, I shall recognise
none of these titles save the last, which I shall employ as the
equivalent of botanist, and I shall use the term zoology as denoting
the whole doctrine of animal life, in contradistinction to botany, which
signifies the whole doctrine of vegetable life.

Employed in this sense, zoology, like botany, is divisible into
three great but subordinate sciences, morphology, physiology, and
distribution, each of which may, to a very great extent, be studied
independently of the other.

Zoological morphology is the doctrine of animal form or structure.
Anatomy is one of its branches; development is another; while
classification is the expression of the relations which different
animals bear to one another, in respect of their anatomy and their
development.

Zoological distribution is the study of animals in relation to the
terrestrial conditions which obtain now, or have obtained at any
previous epoch of the earth's history.

Zoological physiology, las