to be won by these
means. On the contrary, the great benefit which a scientific education
bestows, whether is training or as knowledge, is dependent upon the
extent to which the mind of the student is brought into immediate contact
with facts--upon the degree to which he learns the habit of appealing
directly to Nature, and of acquiring through his senses concrete images
of those properties of things, which are, and always will be, but
approximatively expressed in human language. Our way of looking at
Nature, and of speaking about her, varies from year to year; but a fact
once seen, a relation of cause and effect, once demonstratively
apprehended, are possessions which neither change nor pass away, but, on
the contrary, form fixed centres, about which other truths aggregate by
natural affinity.

Therefore, the great business of the scientific teacher is, to imprint
the fundamental, irrefragable facts of his science, not only by words
upon the mind, but by sensible impressions upon the eye, and ear, and
touch of the student, in so complete a manner, that every term used, or
law enunciated, should afterwards call up vivid images of the particular
structural, or other, facts which furnished the demonstration of the law,
or the illustration of the term.

Now this important operation can only be achieved by constant
demonstration, which may take place to a certain imperfect extent during
a lecture, but which ought also to be carried on independently, and which
should be addressed to each individual student, the teacher endeavouring,
not so much to show a thing to the learner, as to make him see it for
himself.

I am well aware that there are great practical difficulties in the way of
effectual zoological demonstrations. The dissection of animals is not
altogether pleasant, and requires much time; nor is it easy to secure an
adequate supply of the needful specimens. The botanist has here a great
advantage; his specimens are easily obtained, are clean and wholesome,
and can be dissected in a private house as well as anywhere else; and
hence, I believe, the fact, that botany is so much more readily and
better taught than its sister science. But, be it difficult or be it
easy, if zoological science is to be properly studied, demonstration,
and, consequently, dissection, must be had. Without it, no man can have a
really sound knowledge of animal organisation.

A good deal may be done, however, without actual dissection on the