We must not, however, confine attention to the higher multicellular
animals and plants. One of the most important factors in the environment
is the existence of bacteria; and it is of great importance that an
outline of bacteriology should be included in our course of Common-sense
Biology. This outline should be kept close to the common necessities of
everyday life. For the sake of making clear and real to the mind the
manner in which bacteria multiply and the extreme rapidity of the
process, a certain amount of microscopical work ought to be done, the
examples being few, but carefully chosen. This kind of work,
nevertheless, should be kept subordinate. The effects wrought by
bacteria in water, earth and air, in stored foodstuffs, and in the
tissues of the living body are the important subjects for study; and
naturally, connected with these, the conditions which permit the access
of bacteria or which, in the case of noxious bacteria, will best ensure
protection.
The rationale of toxins and anti-toxins, with the relations of these to
the blood-serum should also, in a general way, be known; and moreover
the student should be prepared to learn that many diseases, which are
at present very imperfectly understood--we may take, for instance, forms
of insanity--have their _vera causa_ in the action of toxins, and
require to be treated accordingly.
Perhaps, for those who cannot take more than the shorter courses of our
Common-sense Biology, it will be sufficient to consider only those forms
of inimical bacteria which we have to combat in our own islands. But the
writer would strongly urge that, at least among women of the leisured
classes, this instruction should be extended to cover the bacterial and
other minute parasitic forms of disease most prevalent in our colonies
and in our foreign possessions. The wives of officers, civil servants
and missionaries ought to know, in a clear, scientific way, the causes,
modes of attack, and methods of prevention of the principal tropical
diseases, so far as these have at present been made out.