The information which modern methods of research have given us with
regard to the floating matter in the air is of an importance which cannot
be overestimated.
That the air is full of organic particles capable of life and growth is
now a matter of absolute certainty. It has long been a matter of
speculation, but there is a great difference between a fact and a
speculation. An eminent historian has recently deprecated the distinction
which is conventionally drawn between science and knowledge, but,
nevertheless, such a distinction is useful, and will continue to be
drawn. A man's head may be filled with various things. His inclination
may lead him, for example, to study archaic myths in the various dialects
which first gave them birth; he may have a fancy for committing to memory
the writings of authors on astrology, or the speculations of ancient
philosophers, from Aristotle and Lucretius downward. Such a one may have
a just claim to be considered a man of learning, and far be it from me to
despise the branches of knowledge toward which his mind has a natural
bent. But in so far as his knowledge is a knowledge of fancies rather
than facts, it has no claim to be called science.
Fancies, however beautiful, cannot form a solid basis for action or
conduct, whereas a scientific fact does. It is all very well to suppose
that such and such things may be, but mere possibilities, or even
probabilities, do not breed a living faith. They often foster schism, and
give rise to disunited or opposed action on the part of those who think
that such and such things may not be.
When, however, a fancy or a speculation becomes a fact which is capable
of demonstration, its universal acceptance is only a matter of time, and
the man who neglects such facts in regulating his actions or conduct is
rightly regarded as insane all the world over.
The influence of micro-organisms on disease is emerging more and more,
day by day, from the regions of uncertainty, and what once were the
speculations of the few are now the accepted facts of the majority.
Miquel's experiments show very clearly that the number of microbes in the
air corresponds with tolerable closeness to the density of population.
From the Alpine solitudes of the Bernese Oberland to the crowded ward of
a Parisian hospital, we have a constantly ascending ratio of microbes in
the air, from zero to 28,000 per cubic meter. Their complete absence on
the Alps is mainly due to the absence of productive foci. Organic matter
capable of nourishing microbes is rare, and the dryness and cold prevent
any manifestation of vitality or increase. Whence come the large number
of microbes in the crowded places and in hospitals?
Every individual, even in health, is a productive focus for microbes;
they are found in the breath, and flourish luxuriantly in the mouth of
those especially who are negligent in the use of the tooth brush. When we
speak of "flourishing luxuriantly," what do we mean? Simply that these
microbes, under favorable circumstances, increase by simple division, and
that one becomes about 16,000,000 in twenty-four hours.
The breath, even of healthy persons, contains ammonia and organic matter
which we can smell. When the moisture of the breath is condensed and
collected, it will putrefy. Every drop of condensed moisture that forms
on the walls of a crowded room is potentially a productive focus for
microbes. Every deposit of dirt on persons, clothing, or furniture is
also a productive focus, and production is fostered in close apartments
by the warmth and moisture of the place. In hospitals productive foci are
more numerous than in ordinary dwellings.
If microbes are present in the breath of ordinary individuals, what can
we expect in the breath of those whose lungs are rotten with tubercular
disease? Then we have the collections of expectorated matter and of other
organic secretions, which all serve as productive foci. Every wound and
sore, when antiseptic precautions are not used, becomes a most active and
dangerous focus, and every patient suffering from an infective disease is
probably a focus for the production of infective particles. When we
consider, also, that hospital wards are occupied day and night, and
continuously for weeks, it is not to be wondered at that microbes are
abundant therein.
I want especially to dwell upon the fact that foci, and probably
productive foci, may exist outside the body. It is highly probable,
judging from the results of experiments, that every collection of
putrescible matter is potentially a productive focus of microbes. The
thought, of a pit or sewer filled with excremental matters mixed with
water, seething and bubbling in its dark warm atmosphere, and
communicating directly (with or without the intervention of that
treacherous machine called a trap) with a house, is enough to make one
shudder, and the long bills of mortality already chargeable to this
arrangement tell us that if we shudder we do not do so without cause. As
an instance of the way in which dangers may work in unsuspected ways, I
may mention the fact that Emmerich, in examining the soil beneath a ward
of a hospital at Amberg, discovered therein the peculiar bacillus which
causes pneumonia, and which had probably been the cause of an outbreak of
pneumonia that had occurred in that very ward.
The importance of "Dutch cleanliness" in our houses, and the abolition of
all collections of putrescible matter in and around our houses, is
abundantly evident.
It will not be without profit to examine some well-known facts, by the
aids of the additional light which has been thrown upon them by the study
of the microbes which are in the media around us.
There is no better known cause of a high death rate than overcrowding.
Overcrowding increases the death rate from infectious diseases,
especially such as whooping cough, measles, scarlet fever, diphtheria,
small-pox, and typhus. The infection of all these diseases is
communicable through the air, and where there is overcrowding, the chance
of being infected by infective particles, given off by the breath or
skin, is of course very great. Where there is overcrowding, the
collections of putrescible filth are multiplied, and with them probably
the productive foci of infective particles. Tubercular disease, common
sore throat, chicken-pox, and mumps, are also among the diseases which
are increased by overcrowding.
To come to details which are more specific, let us consider the case of
some diseases which are definitely caused by floating matter in the air.
First, let us take one which is apparently attributable to pollen.