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 is 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, lastly, is the doctrine of the functions or
actions of animals. It regards animal bodies as machines impelled by
certain forces, and performing an amount of work which can be expressed
in terms of the ordinary forces of nature. The final object of physiology
is to deduce the facts of morphology, on the one hand, and those of
distribution on the other, from the laws of the molecular forces of
matter.

Such is the scope of zoology. But if I were to content myself with the
enunciation of these dry definitions, I should ill exemplify that method
of teaching this branch of physical science, which it is my chief
business to-night to recommend. Let us turn away then from abstract
definitions. Let us take some concrete living thing, some animal, the
commoner the better, and let us see how the application of common sense
and common logic to the o