inference, that
if one drop of impure fluid contains countless atoms endowed with
vitality, the same amount of impure air may be equally tenanted with
its myriads of invisible inhabitants.

It is well known that different mixtures, which are at first pure and
apparently free from all insect life, will, in the course of their
fermentation and subsequent impurity, generate peculiar species of
animalcules. Thus all water and vegetable or animal matter, in a state
of stagnation and decay, gives birth to insect life; likewise all
substances of every denomination which are subjected to putrid
fermentation. Unclean sewers, filthy hovels, unswept streets, unwashed
clothes, are therefore breeders of animalcules, many of which are
perfectly visible without microscopic aid.

Now, if some are discernible by the naked eye, and others are detected
in such varying sizes that some can only just be distinguished by the
most powerful lens, is it not rational to conclude that the smallest
discernible to human intelligence is but the medium of a countless
race? that millions of others still exist, which are too minute for any
observation?

Observe the particular quarters of a city which suffers most severely
during the prevalence of an epidemic, In all dirty, narrow streets,
where the inhabitants are naturally of a low and uncleanly class, the
cases will be tenfold. Thus, filth is admitted to have at least the
power of attracting disease, and we know that it not only attracts, but
generates animalcules; therefore filth, insects and disease are ever to
be seen closely linked together.

Now, the common preventives against infection are such as are
peculiarly inimical to every kind of insect; camphor, chloride of lime,
tobacco-smoke, and powerful scents and smokes of any kind. The first
impulse on the appearance of an infectious disease is to purify
everything as much as possible, and by extra cleanliness and
fumigations to endeavor to arrest its progress. The great purifier of
Nature is a violent wind, which usually terminates an epidemic
immediately; this would naturally carry before it all insect life with
which the atmosphere might be impregnated, and the disease disappears
at the same moment. It will he well remembered that the plague of
locusts inflicted upon Pharaoh was relieved in the same manner: "And
the Lord turned a mighty strong west wind, which took away the locusts
and cast them into the Red Sea; there remained not on