rible agency of the parasitic fungi and of the infinitesimally
minute microbes, which work far greater havoc among plants and
animals, has been brought to light. The 'particulate' or 'germ' theory
of disease, as it is called, long since suggested, has obtained a firm
foundation, in so far as it has been proved to be true in respect of
sundry epidemic disorders. Moreover, it has theoretically justified
prophylactic measures, such as vaccination, which formerly rested on a
merely empirical basis; and it has been extended to other diseases
with excellent results. Further, just as the discovery of the cause of
scabies proved the absurdity of many of the old prescriptions for the
prevention and treatment of that disease; so the discovery of the
cause of splenic fever, and other such maladies, has given a new
direction to prophylactic and curative measures against the worst
scourges of humanity. Unless the fanaticism of philozoic sentiment
overpowers the voice of philanthropy, and the love of dogs and cats
supersedes that of one's neighbor, the progress of experimental
physiology and pathology will, indubitably, in course of time, place
medicine and hygiene upon a rational basis. Two centuries ago England
was devastated by the plague; cleanliness and common sense were enough
to free us from its ravages. One century since, small-pox was almost
as great a scourge; science, though working empirically, and almost in
the dark, has reduced that evil to relative insignificance. At the
present time, science, working in the light of clear knowledge, has
attacked splenic fever and has beaten it; it is attacking hydrophobia
with no mean promise of success; sooner or later it will deal, in the
same way, with diphtheria, typhoid and scarlet fever. To one who has
seen half a street swept clear of its children, or has lost his own by
these horrible pestilences, passing one's offspring through the fire
to Moloch seems humanity, compared with the proposal to deprive them
of half their chances of health and life because of the discomfort to
dogs and cats, rabbits and frogs, which may be involved in the search
for means of guarding them.

[Sidenote: Scientific exploration.]

An immense extension has been effected in our knowledge of the
distribution of plants and animals; and the elucidation of the causes
which have brought about that distribution has been greatly advanced.
The establishment of meteorological observations by all civilised
nat