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Class BIOLOGY

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WORKS BY T. MITCHELL PRUDDEN., M.D.

DIRECTOR OF THE PHYSIOLOGICAL AND PATHOLOGICAL LABORATORY

OF THE ALUMNI ASSOCIATION OF THE COLLEGE OF

PHYSICIANS AND SURGEONS, NEW YORK

A Manual of Practical Normal Histology. i6mo,
cloth $i 25

44 A handy book for students. Very practical and very intelligible." —
The American Specialist.

41 We are happy to find that a really valuable addition has been made to
literature. • • . The author is evidently a master of his craft, and
frlly understands the practical details. We are surprised at the amount
of information put in such small compass." — Boston Medical and Surgical
Journal,

The Story of the Bacteria. i6mo, cloth . 75 cents

44 It is written in clear, concise sentences, without any effort at display,
and can be read with profit and enjoyed by any intelligent reader as well
as by the most scientific physician." — Chicago Interocean.

Dust and Its Dangers. Uniform with " The Story of
the Bacteria." Illustrated .... 75 cents

41 It is in one sense an alarmist book, but it alarms in a proper direction,
and performs a service that cannot be overvalued. . . . The
book is to be warmly commended, and should attract general attention."
• — Boston Gazette.

Drinking-Water and Ice Supplies, and Their Rela-
tions to Health and Disease. i6mo, cloth, illustrated,

75 cents.

** Dr. Prudden's little book is crammed with information — practical
information — which to thousands of families would be worth, if duly
read and heeded, far more than money " — Hartford Times.

G. P. PUTNAM'S SONS, PUBLISHERS,

NEW YORK AND LONDON.

DUST AND ITS DANGERS

BY

T. MITCHELL PRUDDEN, M.D.
\ t

AUTHOR OF 11A MANUAL OK PRACTICAL NORMAL HISTOLOGY, THB

STORY OF THE BACTERIA," ETC.

G. P. PUTNAM'S SONS

NEW YORK LONDON

27 West Twenty-third Street 24 Bedford Street. Strand

Ube •fcmcfeerbocfeec press
1904

T7

BIOLOGY

UBRARY

G

COPYRIGHT 1890
BY

T. MITCHELL PRUDDEN, M.E*

Ubc Iknfcfcetbochcr press, flew

PREFACE.

little book has been written with the
J_ purpose of informing people, in simple
language, what the real danger is of acquiring
serious disease — especially consumption — by
means of dust-laden air, arid how this danger
may be avoided.

It is an unpleasant subject ; but it is one
which every one must know something about if
he would avoid such physical ills as are much
more serious drawbacks to comfortable living
than are the temporary mental disquietudes
which this book is designed to inflict upon its
readers.

T. M. P.

131233

CONTENTS

CHAPTER PAGE

I. — THE NATURE OF DUST IN GENERAL . . i

II. — THE LIVING ELEMENTS OF DUST ; WHAT THEY ARE

AND WHERE THEY COME FROM .... 7

III. — How THE LIVING ELEMENTS OF DUST ARE STUDIED . n
IV. — THE MICRO-ORGANISMS OF OUT-OF-DOORS DUST . 20
V. — THE MICRO-ORGANISMS OF IN-DOORS DUST . . 27
VI. — THE SAFEGUARDS OF THE BODY AGAINST INHALED

DUST . . . • . » . « . 36
VII. — THE REAL SIGNIFICANCE OF DUST IN ITS RELATION

TO DISEASE . . . _ . . •* . '.- « . 50
VIII. — CONSUMPTION AND THE WAYS IN WHICH IT is SPREAD

BY DUST . . . . . . . . .58

IX. — DUST-DANGERS OUT-OF-DOORS AND IN PRIVATE

HOUSES, WITH SUGGESTIONS FOR THEIR AVOIDANCE 74
X. — DUST-DANGERS IN PUBLIC BUILDINGS AND PUBLIC

CONVEYANCES . . _. . . . . . .80

XI. — SOME OBJECTIONS, PROTESTS, AND QUERIES AN-
SWERED 87

XII. — SUMMARY AND CONCLUSION 99

INDEX ........... 105

vii

ILLUSTRATIONS.

PAGE

PLATE I. — Different forms of micro-organisms. To face . . 8
FIG. i — A. — A single " colony" of rod-shaped bacteria (bacilli)
growing on a plate of nutrient gelatine. The actual
diameter of this colony was about one fourth of an inch.
B. — A cluster of the bacilli taken from the colony and
highly magnified . . . . . . . .13

FIG. 2. — The " plate method " of air analysis . . . .17

PLATE II. — Colonies of micro-organisms growing on dust

particles. To preced,: . ... . . . .21

PLATE III. — Showing results of " plate analyses" of the air of

different places in New York. To face . . ; .24
PLATE IV. — Effect of sweeping on the number of micro-organ-
isms in the air. To face ...... 32

FIG. 3. — Ciliated cells from the large air-tubes of the human

lungs, seen from the side ...... 39

FIG. 4. — Pigmentation of the lung from inhaled dust . . 44

FIG. 5. — Dust filters in the lung — deeply pigmented . . .47
FIG. 6. — Lymph filters (lymph-glands) at the root of the lung,

the seat of local and healed tuberculosis .... 69

DUST AND ITS DANGERS;

CHAPTER I.

THE NATURE OF DUST IN GENERAL.

IF this were not a practical age, and if the
title on the back of this little book did not
fairly promise a reasonably practical theme, it
might be thought incumbent on the writer,
in this age of nice analysis of very small things,
to be explicit at the outset as to what he does
or does not mean when he says dust. For af-
ter all, when we think of it, there are a good
many kinds of dust. There is, for example,
molecular dust, which swaying ever in space
catches and breaks the sunbeams, giving us
now the deep blue of full day and again the
gorgeous colors of the earlier and later hours.

DUST AND ITS DANGERS.

There are those masses of " water dust " which
we call clouds and fogs and steam. There is
the scriptural dust, bearing, according to ortho-
dox traditions, such a close relationship to the
origin and endings of mundane existence. Col-
loquially, there is a form of "dust" too which to
win many a mortal seems to forget both his
origin and his destiny, yielding at last that dust
which he has won to be himself resolved into
that to which he was foreordained.

But if we plant our standard on Webster's
first choice, and let dust be for us " Fine dry
particles of earth or other matter so attenuated
that it maybe raised and wafted by the wind,"
we shall not be apt to stray too far from the
practical, nor fall foul of either primordial or
ecclesiastical or pecuniary dust.

Simple, common, omnipresent every-day dust
then, — the bane of the tidy housekeeper, the
torment of the cleanly citizen who goes upon
the streets in ill-kept towns, wafted upon every
breeze without, stirred by every footfall within,
— this is the humble but significant subject to
which, not without reason, it is believed, these
pages are devoted.

DUST AND ITS DANGERS.

The dust particles of the air may be roughly
grouped in two classes — first, those larger bodies
which are readily visible in-doors or out-doors,
and second, the smaller particles which are usu-
ally only seen when strongly illuminated.

The coarser particles of dust, such as are
usually swept into our faces whenever we go
upon the streets in New York in dry and
windy weather, consist largely of small frag-
ments of sand, broken fibres of plants, pollen,
fine hairs, the pulverized excreta of various
domestic animals, ashes, fibres of clothing and
other fabrics, particles of lime or plaster or
soot, parts of seeds of plants, masses and clus-
ters of various kinds of micro-organisms, and
other partially ground up materials of kinds
too numerous to mention.

The finer dust particles, whose presence,
when in considerable quantities, we may be
aware of by the choking sensation which they
cause when breathed in, even though we do
not see them, are most plainly visible as the
so-called " motes in the sunbeam," when sunlight
streams into more or less darkened places.
These are very light and consist of fragments

4 DUST AND ITS DANGERS.

of fine vegetable or animal fibres, such as cot-
ton or woollen or other light material, and of
the greatest variety of micro-organisms, either
singly or in masses, such as bacteria and mould
spores. Furthermore, these micro-organisms
are very apt to be found clinging singly or
in clusters to the larger or smaller inorganic
particles of one kind or another which usually
make up the bulk of visible or invisible dust in
inhabited regions.

It is not necessary for our purposes here to
enter in detail into those conditions of soil and
climate and human occupation which favor the
presence of dust in the air. That dry air and
dry-ground surfaces and winds favor the distri-
bution of the fine particles which we call dust,
and that still air and moist ground tend to hold
it in check, are facts which every one's observa-
tion teaches.

It is well known that there are certain occu-
pations which confine persons to closed rooms
or places in which dust particles of one kind
or another are very abundant. Thus day after
day persons confined in air charged with coal-
dust or stone-dust or metallic-dust or cotton-

DUST AND ITS DANGERS. 5

or woollen-dust or tobacco-dust, etc., are apt to
become victims of more or less well marked
pulmonary affections, which are to be found
fully described in systematic treatises among
the so-called " diseases of occupation."

It is not with these exceptional places nor
with the special conditions which belong to
them that we are now concerned, but with the
conditions under which both well and sick peo-
ple of all classes are placed, especially in cities,
and more particularly when in-doors. Nor
shall we occupy ourselves here to any consid-
erable extent with the inorganic ingredients of
dust, but more especially with those living
components called micro-organisms, be they
either bacteria or moulds.

I purpose, in the first place, drawing upon
the results of various old and recent studies, to
indicate the sources of the living germs which
form such an important part of the dust of in-
habited regions, the ways in which they get
disseminated in the air, and their general de-
portment as they are driven hither and thither
by the winds, sway poised in the still air of quiet
places, or settle slowly to the ground.

DUST AND ITS DANGERS.

I purpose then to show the difference of
conditions which prevail, in-doors and out, and
the significance of these conditions in the
problems of ventilation and cleanliness. I
shall then give the results of a series of studies
of the atmospheric micro-organisms in various
places, and consider the relationship of these
aerial germs to some common forms of disease.
Finally, I shall suggest some of the measures
which must be adopted, both by the public au-
thorities and private persons, if both out-of-
doors and in-doors we are to have the privi-
lege of breathing clean and wholesome air. I
shall not, except incidentally, touch upon the
ordinary problems of ventilation or the numer-
ous ways in which by the accumulation of the
products of respiration and exhalation the air
of inhabited rooms may become an active
source of discomfort and ill-health, because the
means by which these evils may be avoided are
well known and are fully explained under the
heading of ventilation in text-books and treatises
on hygiene.

CHAPTER II.

THE LIVING ELEMENTS OF DUST J WHAT THEY
ARE AND WHERE THEY COME FROM.

ALL those forms of minute vegetable life
which swarm in myriads almost every-
where upon the earth's surface are called in
general micro-organisms or germs. Among
these there are three prominent forms which
are called bacteria, yeasts, and moulds (see
Plate I.). Among these the bacteria are by
far the most important. These tiny organisms
are for the most part so very small that many
thousands or millions of them clustered closely
together would not make a mass larger than
the head of a pin. Some of them are round
or ovoidal, some rod-like, some spiral (see
Plate I. Fig. 3). Most of them are harmless
to man, and serve a very important purpose
in the economy of nature in tearing asunder

7

8 DUST AND ITS DANGERS.

dead and worn-out organic material and setting
it free in suitable condition for the building up
of new forms of life. A few species of bacteria,
however, are capable of causing some of the
most wide-spread and most dreaded of human
diseases.

The writer has in another book T described
in simple and untechnical manner the various
forms of bacteria and their relationship to man,
and to this he must refer the reader for fur-
ther details as to their nature and life history.

The moist surfaces of decaying vegetables
and plants and the bodies of animals, all solid
excreta of the bodies of men and animals,
human sputum, stagnant water, the surface of
the soil in inhabited regions, etc., afford fertile
fields of growth for myriads of micro-organisms
of one kind or another.

But we should always remember that bacte-
ria do not become detached from the surfaces
or materials on which they grow or are lodged
while these are in the moist condition. Even
the air sweeping in strong currents through
sewers whose watery contents and moist walls

1 " The Story of the Bacteria."

DUST AND ITS 'DANGERS.

may be swarming with bacteria does not be-,
come charged with these. The bacteria, singly
or in masses, free, or attached to other par-
ticles of one kind or another, must first be
dried and then the clusters more or less pul-
verized or ground up, before they are swept
away and suspended as a part of the dust in
the air.

There are indeed certain moulds — the green
mould, for example, which is so common on
various moist articles of food — which form
very light and not easily moistened spores (see
Plate I. Fig. i), these may be readily brushed
or blown off and mingle with the dust under
almost all conditions.

All sorts of bacteria-laden material then,
when dry and ground up as it so readily is
by the varied movements of men and animals
out-doors and in-doors, may become a part
of the floating dust. These dry minute germs,
some of which are alive and some dead, com-
port themselves in the air just as lifeless dust
particles of any other kind do. They are
wholly inert, and are driven hither and thither
by air currents, now in clouds or masses of al-

10 DUST AND ITS DANGERS.

most stifling density, and again in very small
numbers, collecting in whirls and eddies, and
finally, always sooner or later, settling down to
the lowest available resting-place, as soon as
the buoyancy of air currents gives way to the
ever acting attraction of gravitation. Since
the bacteria of dust are very apt to be in little
groups or clusters or to cling to other dust par-
ticles, most of them readily settle, so that a
very considerable part, in fact, of the finer
dust — the " motes in the sunbeam " — is not
made up of bacteria or germs but of other
forms of lifeless matter.

CHAPTER III.

HOW THE LIVING ELEMENTS OF DUST ARE
STUDIED.

HOW do we find out how many living
germs there are and of what kinds in
a given volume of air ? It will suffice for our
purposes here to say that the bacteria are so
extremely small that the search for them as
they occur in nature is ordinarily of little avail
by the simple use of the microscope.

We have recourse in such studies to what is
called the " culture method." ' By this method,
instead of bringing a portion of fluid or of the
air in which we wish to seek for bacteria di-
rectly under the microscope, we mix a small
portion of the fluid or air with some material
which serves as food for the germs, and on or
in which they will readily grow.

1 See " The Story of the Bacteria."
II

12 DUST AND ITS DANGERS.

This food medium usually contains some
form of gelatine. The gelatinized material is
usually melted when the planting is being done,
and when it cools the bacteria are held firmly
in the position in which they lodged when they
were put in.

The bacteria placed under these conditions
multiply with such great rapidity that usually
in a short time the progeny of a single living
germ will have accumulated to such a degree
right in the spot where the germ lodged
that the mass of them, which we call a " col-
ony " will be readily visible to the naked eye,
or under a low power of the microscope (see
Fig. i). Now since we can readily see the
mass of bacteria which has grown where only
a single germ had lodged we have only to
count the colonies to know how many living
bacteria were present in the volume of air
or fluid which we have tested.

We can now, futhermore, subject the little
colonies which form our bacterial crop to a va-
riety of examinations and tests, and make out
what kinds there are, and further learn their
effects upon man or animals.

DUST AND ITS DANGERS.

Now a good many plans have been devised

for finding out how many living germs are

present in a given volume of dusty air. We

A

FIG. I.

Fig. i. A — A single "colony" of rod-shaped bacteria (Bacilli)
growing on a plate of nutrient gelatine. The actual diameter of this
colony was about one-fourth of an inch. B — A cluster of the bacilli
taken from the colony and highly magnified.

may force a given volume of the air through a
tube which has been plugged with cotton-bat-
ting previously heated so hot as to kill any

14 DUST AND ITS DANGERS.

germs which by chance have been upon it.
The cotton if properly packed in the tube will
catch and hold entangled in its meshes all the
dust particles no matter how small, and with
these all the bacteria which were in the air
which we force through the tube. If now we
carefully pull out the cotton plug with a pair
of perfectly clean forceps, and thoroughly rinse
it off in a small clean flat dish containing our
bacterial food — which we call " the culture me-
dium,"— the germs will be distributed through
the medium, and we cover the dish and set it
aside in a warm place and let it stand until
each living germ has grown and multiplied till
it forms a visible colony. Now we count the col-
onies, and the number represents the number of
living germs which were present in the whole
volume of air which we forced through the cot-
ton plug. There are of course many details
and precautions against error which must be
observed, but this brief description will suffice
for our purposes here.

It has been found in practice, however, that
it is better to use fine sand than cotton in the
tubes to catch the germs, since this is more

DUST AND ITS DANGERS. 1 5

easily handled and is equally efficient as a
filter. We plant the sand together with the
dust which it has caught in the melted culture-
medium, allow it to cool and then stand for a
few days, and when the colonies are grown they
are easily distinguished from the sand particles
by their shape, color, etc., and can be readily
counted. Or, we may use granulated sugar
for a filter, which finally dissolves in the culture-
medium, leaving the bacteria to grow in due
time. This may be called the " filtration
method " of air analysis.

As it requires an accurate and somewhat
complex and cumbersome apparatus to force
or draw the air through either the cotton or
sand filter, another and simpler method is
often resorted to, which, though in some re-
spects less accurate, still gives very useful
results when we wish simply to compare the
germ ingredients of the air in one place with
those in another under similar general condi-
tions.

This simpler method consists in pouring into
a series of perfectly clean shallow glass dishes
a thin layer of the warm gelatinous culture-

1 6 DUST AND ITS DANGERS.

medium and allowing it to solidify by cooling.
This gives a smooth, moist, somewhat adhesive
surface of equal size in each of the dishes,
which are immediately protected from any
chance contamination by closely-fitting glass
covers.

This mode of air analysis depends upon the
fact which we have mentioned above, and
which everybody is familiar with, namely, that
all dust particles, light or heavy, in quiet places,
slowly but surely settle towards the ground.
If now we set one of our covered dishes in a
still place and take off the cover, the dust
particles, the inorganic as well as the living,
will settle on to this moist nutrient surface.
With the inorganic components of the dust, the
multifarious shreds and patches of one thing
or another, this is the end of the matter. But
as the living dust particles touch the surface,
like Antaeus, they find their abeyant vigor
quickly renewed, and forthwith commence to
multiply and inherit their little new-found
earth. Now, suppose we leave our dishes un-
covered and exposed to the falling dust for,
say five minutes ; suppose further that the sur-

DUST AND ITS DANGERS.

face of the culture-medium is three square
inches in size, it will be readily seen that by
the exposure of dishes of the same size for the

FIG. 2. — THE "PLATE METHOD" OF AIR ANALYSIS.
The cut shows the appearance of the flat, shallow dish, the bottom
of which was covered with nutrient gelatin, and when this had cooled
and solidified, was uncovered and exposed to the air in a moderately
clean place for five minutes. It was then allowed to stand in a warm
place for four days. Immediately after the exposure of the gelatin
to the air nothing whatsoever was visible on its surface. But within
a few hours tiny spots appeared which grew larger, some more rapidly
than others. These " colonies," at the end of four days, when the draw-
ing was made, vary considerably in size and appearance, because they
are mostly made up of different species of germs. Each colony con-
sists of thousands of germs (see Fig. I, A), which have grown on the
spot where the lone ancestor fell from the air and stuck fast during
the five minutes exposure of the gelatin.

same time to the air of different places, we
can, by comparing the number of bacterial

1 8 DUST AND ITS DANGERS.

colonies which develop on the surfaces, get at
least an approximate idea of the relative num-
ber of suspended bacteria slowly settling in the
air of the different places (see Fig. 2).

We cannot, of course, by this method say
how many germs were present in a given vol-
ume of air, as we can by the more elaborate
and accurate method given above, and there
are many minor sources of error. For exam-
ple, the mould spores are so very light and
buoyant that they fall but slowly, so that we
may altogether miss many of them, and the
same may be true of some of the lighter bac-
teria. Moreover, even very slight upward air
currents may interfere with the settling of the
germs, and in windy places this method is of
little use. But on the whole, if similar condi-
tions are maintained in the different analyses,
comparative results may be obtained in this
way which are of much value, as we shall pres-
ently see.

This, which we will call the "plate-method,"
enables us to get a general notion of the bac-
terial contents of the air in various places under
conditions which would render the use of the

DUST AND ITS DANGERS.

more accurate and cumbersome apparatus dif-
ficult or impracticable. We can go about with
our innocent-looking little case of glass boxes,
partly filled with nutrient gelatin, as does the
amateur photographer with his detective cam-
era ; though instead of " pulling the string,
touching the button, and leaving the rest to
the manufacturer," we raise the cover, take the
time, and let Nature do the rest.

We are now ready to look at the results of
a series of so-called biological analyses of the
air of various places. We mean by biological
analysis of air, in distinction from the chemical,
an analysis which has for its object the deter-
mination of the number or character, or both,
of the living germs, or micro-organisms which
may be suspended in it.

CHAPTER IV.

THE MICRO-ORGANISMS OF OUT-OF-DOORS DUST.

WE must be on our guard in looking at
the results of such analyses as those
now to be described against hasty inferences
as to their significance. It would be a grave
mistake to suppose that living germs in the
air are necessarily harmful to human beings,
and to infer that air found to habitually con-
tain few bacteria is necessarily more salubrious
than that which contains more. For the pres-
ent, then, let us look upon the results of these
analyses simply from the biological standpoint,
and, if possible, place ourselves in the attitude
of botanists studying the flora of the atmos-
phere, not of physiologists concerned with the
relationship of these tiny plants to man. This
we shall come to by and by when we have ac-
cumulated enough facts to justify such infer-
ences as may urge themselves upon us.

20

EXPLANATION OF PLATE II.

This cut shows the appearances which are presented, after the
germs have grown, by particles of sand and shreds of vegetable fibre
to which single germs were clinging when they settled on to the un-
covered gelatin plate. In this case the drawing was made five days
after the exposure of the plate to the air of a dusty street. The largest
of these colonies were barely visible to the naked eye.

I. — Shows a particle of sand completely surrounded by the colony
or mass of bacteria which has grown from a single germ which was
clinging to the minute sand particle as it settled with the dust.

2. — Shows a tiny shred of wood to which five different germs were
attached as it settled on to the exposed plate. We should probably
have searched in vain, even with a powerful microscope, for the single
germs clinging to it at the time this wooden dust particle planted itself
on the surface of the gelatin. But now the larger colonies are visible
even to the naked eye. We know that they grew from different
species of germs because under a moderate magnifying power they
present such markedly different appearances.

3. — Shows a minute sliver to which four different forms of germs
were clinging as it fell.

DUST AND ITS DANGERS. 21

From the enormous number of bacteria and
moulds, which are present everywhere in in-
habited regions where the conditions are suit-
able for their growth, it might be imagined
that in dry weather the number of atmospheric
germs in the dust out-of-doors would be very
great. But this is not usually the case, even
in large and populous towns. Here and there
along the streets, where these are filthy and
almost never properly cleaned, as in New
York, or where the wind whirls around the
corners of buildings, forming air eddies, the
micro-organisms are often present in very large
numbers, so that one in passing about the town
is apt here and there to encounter veritable
germ-showers. But on the whole, almost
everywhere out-of-doors, except in dangerously
filthy cities, the large volumes of air, which are
more or less constantly passing, so largely di-
lute the local germ-dusty air that the actual
number of micro-organisms in a given volume,
say a cubic foot, is on the average very small,
and usually insignificant. When the ground
is wet and air currents moderate, the number
of germs is still further diminished.

22 DUST AND ITS DANGERS.

It is very difficult to fix upon any definite
number of living micro-organisms in the out-
of-doors air which can be regarded as the usual
or normal number, because the number varies
so extremely under different conditions. Thus
on high mountains or deserts and on the sea
the unconfined air is practically free from
micro-organisms. In the winter months, when
snow is on the ground, during rain storms, and
when the air is still, the number may be very
small. On the other hand, a high wind blowing
across a region rich in dry and pulverized
germ-laden material, will for a time disseminate
large numbers of micro-organisms ; but at the
same time it tends, by the dilution which it
affords, and by carrying them off to other re-
gions, to speedily reduce the numbers in any
given place. A rainfall, to a certain extent,
tends to free the air of its germs by washing
them down, while during a snowstorm many
are caught in the snow crystals as they form.

In wet weather mould-spores tend to pre-
dominate, partly because they then grow readily
and partly because they are very light, and not as
easily wetted and held down as are the bacteria.

DUST AND ITS DANGERS. 2$

The analysis of out-of-doors air shows, as
might be expected, a great deal of variation
in the number of living germs present in a
given volume. Ten litres, which is about 600
cubic inches (that is a volume equal to a cube
of about 8 inches square), is the volume of
air usually taken as a sample for purposes of
analysis.

Carnelly found in still out-of-doors air, in
the town of Dundee, in Scotland, as the result
of 14 analyses, an average of less than 10
bacteria in 10 litres of air, while in another
place there were over 1 70 in the same volume.

Tucker found the air in Boston, from a
secluded place, but in the immediate vicinity
of its traffic, during the mild but rather windy
weather in November, December, and January,
with no snow on the ground, to contain on the
average of 56 analyses, less than 20 bacteria to
10 litres. In an open court at the Hygienic
Institute in Berlin, Petri found, as a rule,
equally small numbers.

The average of 1 3 analyses, made in March
and April, 1 890, of the air from the yard of the
College of Physicians and Surgeons, in New

24 DUST AND ITS DANGERS.

York, at a place as far from the streets as pos-
sible, and about 25 feet from the ground, showed
the number of bacteria in 10 litres to be 56 and
of moulds 4.

Analyses, during the same period, of the air
of the streets in New York, from various parts
of the town,1 showed the average number of
bacteria in 10 litres to be 376, and of moulds
6. These analyses of street air were made
under ordinary conditions, at such times of the
day 'as the air appeared to be at its best.

If an analysis is made of the air in the dust
clouds which sweep along the ill-kept streets
of a city like New York or which blows from
the street sweepers as they pass along the
unwatered thoroughfares into the houses or
over the unwary passer-by, the numbers of
germs to the litre is startling.

Let us look at a graphic record of the rela-
tive number of bacteria in various places, made
by the plate method already described.

Plate III. shows the result of a series of
comparative analyses made in this way in var-

1 This was at a time when the so-called politicians were juggling
with the Street Cleaning Department while the streets were largely
left to take care of themselves.

PLATE III. — SHOWING RESULTS OF " PLATE ANALYSES " OF THE AIR
OF DIFFERENT PLACES IN NEW YORK.

(See explanation in the text.)

DUST AND ITS DANGERS. 2$

ious places in New York on a clear, dry, mod-
erately breezy day, in April, 1890. Each one
of the spots represents a colony of bacteria,
which has grown from the single germ which
settled on to the moist surface during the five
minutes exposure to the air.

1. Ball Ground, Central Park. — A mod-
erate westerly wind bringing dust over from
the Eighth Avenue and its cross streets.

2. Union Square. — At the edge of the
fountain basin.

3. The library of a private house not far
from 34th Street and Broadway.

4. A large retail dry-goods store on one of
the uptown cross streets near Broadway, during
a busy hour of the day, when there was much
stir and bustle.

5. Railing of the small park at Broadway
and 35th Street.

6. A cross street through which the carts of
the Street-Cleaning Department were passing
collecting the dry heaps of street dirt.

If we translate into numbers the appearances
of the cultures shown in Plate III., we find that
during five minutes the number of living germs

26 DUST AND ITS DANGERS.

which settled from the floating dust on to the
bottom of a round dish about 3f inches in
diameter in different places in New York was
as follows :

1. Central Park. — Dust blowing from an
adjacent street, 499.

2. Union Square, 214.

3. Private house, 34.

4. Large retail dry goods store, 1 99.

5. Broadway and 35th Street, 941.

6. Street in the process of being cleaned, by
the Street-Cleaning Department, 5,810.

A sufficient explanation of the number of
germs in the air at the lower part of Central
Park is found in the westerly wind and the ex-
tremely filthy condition of the streets on the
windward side. The result of the analysis
shown in fig. 6, needs no lengthy comment.
That as many living germs as of colonies
which are here seen growing should be float-
ing in the air and liable to be breathed in by
any unfortunate passer-by within five minutes,
is evidence enough of the filthiness of the
present practices of so-called street-cleaning in
New York, As to its danger, more by and by.

CHAPTER V.

THE MICRO-ORGANISMS OF IN-DOORS DUST.

WHEN we consider the comportment of
dust particles in closed rooms, we see
at once that the great renovating and cleansing
agency which is so efficient out-of-doors is, ex-
cept on special occasions, absent, namely, the
winds and strong air currents and the more or
less frequent and prolonged wettings. Once
in a closed room dust is very apt, as every
housekeeper knows, to stay there, unless
special means are resorted to to get rid of it.
But although the dust remains in the room,
those heavier parts of it which contain most of
the bacteria gradually sink to the lowest
available levels, floors, shelves, furniture, etc.,
so that it has been found that the still air of a
room may almost completely free itself from
micro-organisms, except some of the lighter

27

28 DUST AND ITS DANGERS.

mould spores, within one or two hours. Of
course violent currents of air, walking about,
etc., interfere with the very complete subsi-
dence of the bacteria-laden dust particles.

Now it might be supposed that the frequent
renewal of the air of a room by such a system
of ventilation as would be effective in keeping
its gaseous ingredients pure would also suffice
to rapidly carry off dust particles, and bacteria
as well. But a long series of most carefully
conducted experiments by Stein has shown
that this is not the case. Even when the in-
troduction of fresh air is pushed to the com-
plete renewal of the air three times an hour,
the number of suspended micro-organisms
floating in the air is scarcely more diminished
than they would be by settling in still air.
Stein found that only when the ventilation
was carried to the degree of inducing marked
and disagreeable draughts in the room was
there a rapid diminution in the number of
micro-organisms which had been diffused arti-
ficially through the air for the purposes of the
test. Of course opening of the windows and
allowing large bodies of air to blow through

^ \ *» " " T ^V
S ^ jr T« A

I rrY )

XOf Dl

DUST AND ITS DANGERS. 29

the room, quickly resulted in sweeping away a
large proportion of the suspended micro-or-
ganisms. But this observer also found that
even very strong air currents were not able,
when sweeping over woollen and other fabrics,
carpets, hangings, etc., which had been be-
strewn with bacteria-laden dust, to free the
germs to any considerable extent from these.
The strong air currents carried off the sus-
pended particles, but those which had settled
on to the fabrics and floors were but little
affected. The practical bearings of this ob-
servation we shall see by and by.

When we consider the constant tendency of
dust particles to settle as soon as they find
themselves in quiet places out of strong air
currents, and the fact that even ordinarily
efficient systems of ventilation do not carry off
any considerable proportion of the dust par-
ticles from closed still rooms, we are led to the
rather startling conclusion that the ordinary
living-rooms, even though they be well ven-
tilated, are actually dust and bacteria reposi-
tories, and that when by a system of forced
ventilation we cause large volumes of dust-

30 DUST AND ITS DANGERS.

laden air from out-of-doors to pass through
them we are actually, so far as micro-organisms
are concerned, cleansing the air and sending it
out much freer from germs than when it en-
tered, these having slowly settled as the air
made its way from the entrance to the exit of
the ventilating openings. The same of course
applies, though in a less striking way, to the
so-called natural mode of ventilation — that is
a ventilation system which has for its exit a
warm air-shaft or chimney, and " trusts to
luck " for channels of air entrance through
loose joints in windows, doors, and walls.

Now, although in rooms through which for
purposes of ventilation large volumes of dusty
out-of-doors air are pumped, day and night,
there will be in the aggregate a considerable
accumulation of more or less bacteria-laden
dust, it is, after all, the ground-up dirt which
we bring in from the streets upon our shoes
and garments, and the accumulations of waste
material, which in dwelling-houses and places
of assembly are so abundant, which furnish the
larger proportion of the bacterial ingredients

of in-doors air. The marked difference be-
3

DUST AND ITS DANGERS. 31

tween the atmospheric dust in closed rooms
and that out-of-doors is that in the former
there is no spontaneous mode of purification
of the air except that of settling, and that the
settled more or less bacteria-laden dust is
liable to frequent stirring-up by the ordinary
movements of people, while out-of-doors the
bacteria-laden air is constantly being swept off
by the wind.

The effect of stirring about in rooms in
which micro-organisms are present is shown by
the analyses of Tucker in the wards of the
Boston City Hospital. He found that about
midnight after the wards had been quiet for a few
hours, the number of living bacteria in 10 litres
of air ranged from o to 13, while the number of
mould spores ranged from o to 4. The air had
practically freed itself from germs, by settling
to floors and beds. He found that in a long
series of hourly determinations in various wards
at all hours of the day, the average number of
bacteria in 10 litres of air was about 26 and of
moulds about 12, the number of bacteria rang-
ing from i to 477; of moulds from o to 227.
The germs were more abundant in the air in

32 DUST AND ITS DANGERS.

the forenoon when the beds were being made
and the wards cleaned and put in order. He
found that sweeping nearly doubled the number
of germs in the air already disturbed by the
routine work in the wards in the morning, and
considering the number of germs in the 10
litres of air in the early morning before the
wards were astir as the minimum — i — the
general cleaning routine work and sweepi-ng
were capable of increasing the number, on the
average, seventy times.

The difference in the number of living germs
floating in the air of a room before and after
sweeping, is graphically shown in Plate IV.
The room in which these analyses were made,
was a most carefully kept hospital ward in New
York, in which were about 25 persons. Be-
fore the sweeping, when quiet had prevailed
for about an hour, the number of living germs
which settled on to the dish, 3^ inches in di-
ameter, was 12 (see Plate IV., Fig. i). Im-
mediately after sweeping, the number which
settled on to a similar surface, was 226 (see
Plate IV., Fig. 2). Very much larger differ-
ences are often found in the number of germs

DUST AND ITS DANGERS. 33

in the air before and after sweeping, if the
rooms are not frequently carefully and properly
swept and dusted. Thus in a carpeted living-
room in a tenement on loth Avenue, 75 bacteria
and i mould settled on to the surface of the
exposed plate in five minutes before sweeping.
When the room was still, immediately after
sweeping, a similar experiment showed over
2,700 bacteria and 6 moulds.

Carnelly found in hospital wards in Dundee
in the afternoons from 10 to 20 bacteria in 10
litres of air. Neumann found after sweeping
from 80 to 140 bacteria, and later in the day
from 4 to 10 in 10 litres. On the other hand,
Carnelly found in houses which are denomin-
ated clean, 180 bacteria in 10 litres of air,
while in very dirty houses there were over
900. In dirty school-rooms, with the so-called
natural ventilation, he found in the same vol-
ume of air nearly, 2,000 living bacteria, while
in mechanically ventilated schools there were
from 30 to 300.

The writer has found as the result of 23
analyses of the air of various laboratories,
lecture-rooms, and hall-ways, at the College of
\

34 DUST AND ITS DANGERS.

Physicians and Surgeons in New York, under
the ordinary conditions of occupation by con-
siderable numbers of students during March and
April, 1890, that the average number of bacteria
in 10 litres was 11 and of moulds 14.

The average number of germs in various
hospitals and dispensaries in New York during
the same period in 10 litres of air, (19 analyses)
was bacteria 127, moulds 25.

We thus see that the number of living germs
in a given volume of in-doors air varies greatly
in different places and under different con-
ditions. We see that the temporary freeing of
the in-doors air from germs can be accomplished
by simply closing the rooms and keeping the
contained air still when within one or two
hours nearly all dust and most of the bacteria
will have settled to the lowest resting-place.
Whether the air shall be permanently rid of its
living or inert dust particles or not, will of
course depend upon the measures which are
resorted to in the familiar performances of
sweeping and dusting, of which more by and by.

A good many of these facts which have been
just set down in regard to dust, are embodied

DUST AND ITS DANGERS. 35

in the lore of the intelligent house-keeper,
scientific studies having simply given precision
to common beliefs and revealed certain quali-
ties in dust, which may possibly render it of
greater significence than an annoying and an
omnipresent form of dirt.

CHAPTER VI.

THE SAFEGUARDS OF THE BODY AGAINST IN-
HALED DUST.

HAVING now gathered together a con-
siderable number of facts about the
distribution in the air of dust particles and
among them of living germs, we are ready to
consider their significance — if they have any —
to human beings, who must live in and breathe
this more or less dust-laden air.

The average amount of air which a healthy
grown person takes in at each breath has been
estimated to be about one half a litre (about
30 cubic inches). We have seen from our
various analyses of the air of different places in
and about New York, under ordinarily favor-
able conditions, that the number of living
germs in 10 litres of air varies from 1 1 to 376.
So that basing our estimate upon these studies

36

DUST AND ITS DANGERS. 37

of the air in this city, with every twenty
breaths one may take into his body, depending
upon where he is all the way from u to 376
living micro-organisms, together with a variable
amount of inorganic dust.

The number of living germs which the New
York citizen is liable to be forced to take into
his body, when the streets are dry and the
wind blowing, or when the dry filth is being
stirred up by the diabolically careless proceed-
ures of the present street-cleaning fiends, it
would be a thankless task to tell.

Now it has been learned, not only from com-
mon experience but from long series of careful
experiments, that the solid particles which we
breathe in with the air either through the nose
or mouth do not come out with the expired air,
but are retained on the moist surface upon
which the air impinges going in and coming
out. These foreign particles floating in the
inspired air are caught largely in the nose or
mouth or upper throat, while a certain number
pass down into the air-tubes and lungs. A
large part of this foreign material may be dis-
charged from the nose where it is caught in the

^ \ & K A /? y

it?

UNIVERSITY

38 DUST AND ITS DANGERS.

mucous which that organ secretes when irri-
tated.

A very considerable proportion of the in-
breathed foreign material gets into the mouth
and may be spat out or swallowed.

The floating material which is carried past
the well-guarded portals of the lungs and
enters the windpipe and bronchial tubes and
lodges on their moist walls finds here a most
efBcient arrangement for its expulsion. Here
is placed, completely lining the tubes, an army
of thoroughfare-cleansers composed of individ-
uals who are not in politics, who have no vote,
and who present to us the unwonted, and at
first puzzling, spectacle of street-cleaners whose
business seems to be to clean the streets.
Completely lining the larger air-tubes like
a mosiac, are myriads of tiny cells shaped
something like a narrow short club and set
upon end side by side. Projecting from the
free ends of each one of these cells is a number
of very minute hairs, so that the whole cell
looks something like a short club with a beard
growing from one end (see Fig. 3). The
whole inner surface of these air-tubes, then, is

DUST AND ITS DANGERS.

39

lin^d with these delicate hairs which are called
cilia.

Now, these myriads of cilia, year in and year
out, day and night, while life lasts, are con-
stantly swinging their free ends back and forth,
bending as they recover, and then with a quick

L

FIG. 3. — CILIATED CELLS FROM THE LARGE AIR-TUBES OF THE
HUMAN LUNGS, SEEN FROM THE SIDE. HIGHLY MAGNIFIED.

snap forward so that any small object which
lodges on the walls of the larger air-tubes—
since all the cilia act in rhythm — is swept up-
wards toward the mouth, away from the peril-
ously delicate and sensitive lungs.

The movement of these cilia is less vigorous
when the body is quiet, as in sleep, increasing
m rap«<sh-Uj ond -fa-rce when Ifre ia^y )$ *cf i^e ••

.

40 DUST AND ITS DANGERS.

in rapidity and force when the body is active.
Almost every one has noticed that shortly after
rising more or less mucus or " phlegm " is apt
to come up into the throat. This is because the
increasing vigor of the ciliary movement, as
one's general activity increases, sweeps up the
accumulation which the comparative quiescence
of the night has allowed to form.

It is a curious thing that these humble but
energetic little members of the cell communi-
ties which make up the body are apparently the
last elements to die when what we sometimes
call the vital forces no longer act. The breath
ceases, the heart flutters and is still, the blood
ebbs and flows a little here and there, the last
definite nerve impulses express themselves as
now one now another muscle quivers or feebly
and fitfully contracts, but still these wonderful
little cilia keep swinging on sometimes for
hours after all trace of what we have called
life has disappeared, and when these too at
last are still, and not till then, is life in the
body totally extinct.

There is another very curious arrangement
in the air passages for the disposition of small

DUST AND ITS DANGERS. 41

foreign bodies which are breathed into the
lungs. There are certain cells in the body
which seem to have nothing in particular to do
on ordinary occasions but to float about on the
blood tides or wander through the various
channels and crevices of the tissues watching
other cells work. Sometimes they come out
and air themselves in the bronchial tubes or in
the tiny air-chambers which make up the body
of the lungs. But the moment these cells
come upon a foreign particle from without or
upon a fragment of worn-out tissue anywhere
in the body they pounce upon it, wrap them-
selves around it, and either digest or destroy
it or carry it off to some safe place of deposit,
either inside the tissues or without. Now these
humble scavenger cells are usually quite abun-
dant in the air passages, where they often take
up dust particles of one kind or another, and
victims to their zeal are not infrequently swept
with their booty by the ciliated cells up and
away into the mouth. A good deal of lore has
accumulated about these little wandering scav-
engers of the body and they seem to be of great
importance in many ways. But, in spite of

42 DUST AND ITS DANGERS.

their usefulness and the various beneficent
things which they do, scientific men have seen
fit to make them bear the added burden of the
name of phagocytes.

But to return to our dust particles. In spite
of all the safeguards with which our lungs are
furnished against the entrance of foreign
bodies, into their deep and delicate recesses
and through them into the blood, a considerable
number of dust particles of one kind or another
do get in and permanently lodge upon those
walls of the delicate breathing chambers in the
lungs, which are beyond the protecting agency
of the ciliated cells. Now right in the walls
of these tiny air-chambers of the lungs, where
the blood is separated from the inbreathed air
only by a film, one of the most important and
subtle of the vital process goes on, upon which
the continued purity and virtue of the blood
depends. Here the blood gives up the car-
bonic acid and water which it has gathered in
its journey around the system, and takes in its
fresh supplies of oxygen.

Although persons who habitually work in
very much dust-laden air are liable to pul-

DUST AND ITS DANGERS. 43

monary disease caused by the lodgment in
their lungs of foreign particles of one kind or
another, and furthermore, although even com-
paratively small amounts of foreign particles in
the lung tissue cannot fail to be undesirable
additions to those organs, still it is a fact that
the lungs do establish for themselves a consid-
erable degree of what we call tolerance of for-
eign particles lodged in their tissues. That is
to say, there may be a good deal of accumula-
tion of foreign material in the lungs without
any appreciable interference with the health,
because the body here, as in many other ways,
has the power of adapting itself to unusual and
even harmful conditions.

In fact, the lungs of nearly all adults who live
under what we call civilized conditions, that is,
in houses with considerable smoke and dust in
the air, in cities which have street-cleaning done
for political purposes only, or in manufacturing
regions where there is much smoke, instead of
being of a delicate spotless pink color are dotted
all over with spots and streaks and patches of
inhaled dust-particles which the body has not
been able to get rid of but has stowed away

44 DUST AND ITS DANGERS.

permanently in the tissues in such situations as
will least interfere with the action of the lungs
(see Fig. 4). Here it remains as long as life
lasts.

FIG. 4. — PIGMENTATION OF THE LUNG FROM INHALED DUST.

A small portion of the surface of an adult human lung which has
become pigmented by the inhalation of dust. This drawing was
made not from the lung of a coal miner or one who had lived in
especially smoky or dusty places, but from that of an individual ex-
posed to the ordinary conditions of in-door city life.

But we have not yet finished with the safe-
guards which the body has placed for itself
against inhaled dust. For, however success-

DUST AND ITS DANGERS. 45

fully the lungs may stow it away in consider-
able quantities, there is a very curious provision
against its further entrance to and distribution
in the body. This is the way that is provided
against. As the blood circulates through the
lungs as well as in every other part of the body,
a small amount of its fluid part, conveying an
abundance of nutriment, oozes out through the
walls of the vessels into all the minute clefts and
crannies of the tissues where the cells lie and
bathes and nourishes them. Now, having done
this, the nutritive fluid — which we call lymph —
is gradually collected into a series of irregular
narrow vessels which open into large and still
larger trunks until finally it is poured back into
the blood, of which it again becomes a part.

If this lymph which has searched out every
remotest corner of the body to which it was
distributed should have become contaminated
or polluted by any harmful or foreign material
which it had come across in the tissues, it would
carry it straight back and pour it into the blood,
where it might cause dire results, since the
blood is an extremely important and delicate
juice. But fortunately the lungs, as well as

46 DUST AND ITS DANGERS.

several other important organs of the body, are
provided with a series of very efficient filters,
through which the lymph has to pass in its
transit toward the blood current with which
it is to mingle. Now several of these living
filters, which we call " lymph-glands," little
reddish-white bodies, are grouped deep in the
chest at the root of the lungs, and are so
very effective that, although the lungs may
be crowded with inhaled dust particles stored
away permanently in out-of-the-way places, and
the lymph filters may finally become themselves
as black as your hat from its accumulation
(see Fig. 5) the dust rarely gets through them
and into the blood or other parts of the body.

Thus far, in considering the safe-guards of
the body against inhaled dust, we have been
thinking only of those lifeless particles of one
kind or another which make up the inorganic
part of dust. How is it with bacteria, — with
those dust particles which are quite inert when
dry in the dust, but which, when the moisture
and warmth and food they need are furnished,
may grow and multiply with great rapidity.

DUST AND ITS DANGERS.

47

In answer to this, it should be said that not
only does the body afford the same safe-guards
against these living germs as against other
dust particles, as just described, but most of
the different kinds of germs which are floating

FIG. 5. — DUST FILTERS IN THE LUNG DEEPLY PIGMENTED.

A drawing of one lobe of a human lung, showing the lymph filters
(lymph-glands) at one side, which have caught so much inhaled dust
in their meshes— thus keeping it out of the blood — as to have become
almost totally black. These glands are naturally of a light-pink color.

in the air do not grow in the human body in
any appreciable degree ; the soil is not good
for them. Some do not find in the nose, or
the mouth, or the lungs, the proper food or
conditions which they need, others are actually
killed off sooner or later, either owing to some

48 DUST AND ITS DANGERS.

quality in the body juices which is quite in-
imical to their life, or by those vigilant phago*
cytes which we have noticed above — or per-
haps in other ways which we do not yet know
any thing about. The germs which are swal-
lowed after being caught in the nose or mouth
from the inspired air, or swept up from the air-
tubes by the ciliated cells, are, for the most
part, soon deprived of life by the digestive
fluids.

There is one species of bacteria which we
are to learn more about presently (the tubercle
bacilli) which, when they lodge in the tissues,
sometimes stimulate the cells near them which
multiply and build up a dense enclosing wall
about the intruding germs, so that these be-
come imprisoned in a little bag or sac in the
body, and can neither get away, nor spread, nor
do further damage. They are sometimes so
cut off from nutriment, that they die, or at
best sustain for some time, a poor and meagre
existence. (See Fig. 6, p. 69.)

There are individual conditions of the body
in which it affords a most obstinate resistance
to the incursions — that is, the growth of bac-

DUST AND ITS DANGERS. 49

teria within it. There are other conditions in
which it seems fairly predisposed to their
growth and ravages. What the nature of the
conditions is, which in one individual or at one
time confers immunity to harmful bacterial
growth, and at another renders it predisposed
to their ravages, we do not know. But very
zealous workers are busy with the problem, and
we may hope in due time to get light and con-
fidence in this obscure field, where we can now
but feebly grope.

CHAPTER VII.

THE REAL SIGNIFICANCE OF DUST IN ITS RELA-
TION TO DISEASE.

BUT why then, it may be asked, all these
sinister allusions to the danger of dust,
if, as we have seen in the last chapter, most of
it is caught before it gets into the lungs, and
that which does get in is disposed of in such
clever ways ? This question brings us at last
face to face with the gist of the whole matter.
The body does rid itself of a great deal of the
inhaled inorganic dust which lodges in the nose
and mouth and air-tubes of the lungs. It does
do the best it can to dispose of that which is
permanently stowed -away in the lung tissues
themselves. It does without more ado kill out-
right or otherwise make way with most of the
living germs. But when all this is accomplished
there still remain certain important ways in

50

DUST AND ITS DANGERS. 5 1

which dust particles of one kind or another
may do serious harm to human beings.

We shall do well in considering these
harmful effects of dust to separate in our
thought its inorganic from its germ ingredi-
ents.

The inorganic elements of dust when present
in large quantities in the inhaled air may, as
we have seen above, cause well-defined disease
of the lungs by the persistent irritation which
they induce. But as it is only under excep-
tional conditions, as among coal-miners and
grinders and other workers in confined places
where these solid particles are set free in great
numbers that this occurs, we need not con-
sider them here. Very moderate amounts
of dust particles in sensitive persons cause
such a degree of irritation of the respiratory
organs as either to deprive them of robust
health or predispose them to the aquirement
of various diseases which with unirritated
lungs they would readily resist.

There is no doubt that a great deal of
misery, if not positive disease, is caused by the
inhalation of dust in the persistent coughs and

52 DUST AND ITS DANGERS.

more persistent protean catarrhs with which
so many persons otherwise healthy are bur-
dened.

Then again dust may produce much distress
when not inhaled, by irritating the eyes to such
a degree as to cause great discomfort, if not
positive disease.

The pernicious and noxious elevated rail-
roads have brought some parts of New York
into a condition very much akin to certain
coal mines, with the large amounts of dust and
fine cinders which they shower down upon the
streets and into the adjacent houses and into
the eyes and lungs of the pitiable citizens
of this metropolis.

As to the bacteria about which our main in-
terest centres, there are unfortunately a few
species which, when they once find lodgement
in one place or another in the organs of
respiration, may grow and multiply, and suc-
cessfully resisting all the protective agencies of
the body, set up distinct, persistent and even
fatal disease. Those forms of bacteria which
can or in these regions commonly do this, are
insignificant in number in comparison with the

DUST AND ITS DANGERS. 53

harmless species with which dust is usually
swarming. But few as they are they have an
extreme significance. If it were not for these
few species of disease-producing bacteria most
people could perhaps afford to be as indifferent
as they are to dust and its dangers.

We have seen that the large numbers of
common bacteria which are omnipresent in the
air are growing all about us and get into the
dust in many ways which we not only cannot
control but do not very much care to control,
since in moderate numbers they are essentially
harmless, or at least do only such damage as
other inorganic dust particles may do. But
with the bacteria which cause disease the case
is entirely different. They do not flourish
apart from the bodies of men and animals.
They may remain alive for a good while out-
side of the body, and some of them may grow
a little under some few special conditions.
Some of them are frequently present in the
healthy human body.

But after all when we seek for the active
breeding-places and sources of distribution of
the bacteria which frequently cause disease in

54 DUST AND ITS DANGERS.

man in this region, we find that they are the
bodies of persons, and occasionally animals,
suffering from the diseases which the bacteria
cause. It is the presence of these bacteria in
large numbers given off from the body, which
makes these diseases what we. call contagious
or infectious.

If we could completely isolate all those per-
sons or animals who are at the present moment
harboring the few known species of bacteria
which produce disease in man, such diseases
could be completely stricken from the list of
human ills, unless they were lighted up afresh
by some of the discharged material which on
walls, or garments, or in the soil, or in the
aerial dust, still retained vitality. At any rate,
if we could be certain that the discharged
material from such sick people were immedi-
ately destroyed we should be able to limit
within narrow bounds those diseases which to-
day carry off, prematurely, the larger part of
those who do not die of injuries or of old age.
They are thus, at least ideally, preventible
diseases.

But this matter of preventing the spread of

DUST AND ITS DANGERS. 55

bacterial disease by means of dust is of such
extreme importance that we must be very cer-
tain that we are dealing with facts and not with
conjectures, when we consider the relationship
one to the other. Let us then get the facts
together first.

There is a large number of diseases which
physicians call infectioits ; these all have cer-
tain ways of manifesting themselves, certain
family traits which would justify this grouping
of them together even without a knowledge of
the particular agent which causes them. The
more important of these infectious diseases
are : consumption or tuberculosis, diphtheria,
small-pox, yellow-fever, Asiatic cholera, ty-
phoid-fever, scarlatina, measles, pneumonia,
erysipelas, and blood-poisoning. There are
others of less frequent occurrence in this re-
gion, which we need not mention here.

Now within the past few years we have found
out positively and without question that the
particular and exclusive agent which causes
some of these diseases is one or other form of
bacteria. Each disease has its special form of
bacteria, without which it can by no possibility

56 DUST AND ITS DANGERS.

exist. The particular species causing some of
these diseases have been isolated and studied
and experimented upon in so many ways and
by so many workers that we feel perfectly cer-
tain about them. Among such diseases are :
consumption, typhoid-fever, Asiatic cholera,
erysipelas, some forms of blood-poisoning, and
diphtheria.

Concerning the kinds of germs which cause
many other of the infectious diseases we are
yet in doubt. We have an increasing convic-
tion that they are also caused by some form of
micro-organism or germ, but what it may be
and how it acts is not fully determined.

Among those infectious diseases the exact
causes of which have not yet been made out
may be mentioned small-pox, yellow-fever,
measles, and scarlatina.

Now to make a long story short, and to give
precision to our theme, I purpose to limit this
consideration of the relationship of dust to
disease largely to that one bacterial malady
which is most important and which we know
most about and which we can do most to pre-
vent, namely, consumption or tuberculosis.

DUST AND ITS DANGERS. 57

Many of the conclusions to which we shall
be forced, and many of the practical hints as
to personal action which we shall gain, apply
equally to some of the other bacterial diseases.
But these other diseases are apt to make peo-
ple early and more or less seriously ill, and so
they come under the charge of the physician,
who should on the spot suggest measures to
prevent their spread. On the other hand, per-
sons affected with consumption very frequently
go about for weeks and months among their
fellows, always liable, through ignorance or
carelessness, to transmit the disease-producing
germs to others, as well as constantly repoi-
son themselves, and thus greatly diminish the
chances of recovery which they might other-
wise anticipate.

It is most important then that everybody
should have some definite knowledge about
the cause and mode of spread of consumption,
since it spares no age and no class and is the
most widespread and fatal of all the diseases
known to man, and is in large degree, could
we but secure thorough cleanliness in the air
we breathe and the food we eat, a distinctly
preventible disease.

CHAPTER VIII.

CONSUMPTION AND THE WAYS IN WHICH IT IS
SPREAD BY DUST.

THE germ which causes consumption or
tuberculosis is a minute slender rod-like
body about one ten-thousandth of an inch in
length, and is called the Bacillus tuberculosis.
It does not grow in nature outside of the bodies
of men and a few species of warm-blooded
animals. It may, however, remain alive for
a long time when dry as in the soil or air.

In the bodies of some animals and in the
bodies of many men it does not ordinarily
flourish or even grow at all, for reasons which
we do not understand. The proper tempera-
ture may be present and moisture and nutritive
material in abundance, but for some unknown
reason it will not grow. There are other in-
dividuals and other animals which seem to

DUST AND ITS DANGERS. 59

furnish the unknown conditions, and in them
the bacillus grows more or less rapidly ; such
persons or animals are said to be predisposed
to the disease — consumption.

A great deal of misery and wearing appre-
hension have been caused in the years which are
past by the widespread notion that consump-
tion may be inherited. Modern researches
show that this notion is not well-founded. It
is true that there is a subtle make-up of the
body cells in certain persons, some entirely
mysterious nutritive condition, which renders
their bodies especially favorable for the growth
of the tubercle bacillus, and that this indefinite
and ill-understood peculiarity may be inherited.
But that is all. If the tubercle bacillus can
be kept away from them, even predisposed
persons cannot get consumption, for this dis-
ease without the bacillus cannot exist, and the
bacillus does not as far as we know pass from
the mother to the unborn child. But this so-
called predisposition is not always inherited ;
it may be and often is acquired, sometimes in
ways which we know about, sometimes in ways
which we do not fully understand.

DUST AND ITS DANGERS.

When the tubercle bacilli get into the bodies
of predisposed individuals and begin to grow
they stimulate the tissues about them so that
little new-formed masses of cells appear about
and among the growing germs. These cell
masses are called tubercles. Sometimes larger
masses of new cells are developed, which re-
place considerable portions of the tissues and
organs in which the bacilli have lodged. After
a time, especially in the lungs, the new-formed
tissue, containing sometimes enormous num-
bers of the living tubercle bacilli, gradually
disintegrates or breaks down, and this broken-
down germ-laden material may then be dis-
charged with the mucus from the bronchial
tubes day after day in considerable quantities
for months or even years, in the expectoration,
new bacilli forming as fast as the old are dis-
charged and sometimes even much faster.

Tuberculosis may have its seat in other parts
of the body than the lungs, but with the lung
affection alone we are now concerned.

This then is the great primary fact which is
of extremest significance to us in our present
study ; namely, that every person suffering

DUST AND ITS DANGERS. 6 1

from consumption of the lungs may be expector-
ating every day myriads of living and virulent
tubercle bacilli, and that the life and virulence
of these bacilli are not destroyed by prolonged
drying.

Now leaving this fact for a moment, let us
see how common a disease consumption or
tuberculosis is after all.

From one seventh to one fourth of all the
people who die are carried off, most of them
prematurely, by this disease. In Europe about
one million persons die each year from con-
sumption, that is about 3,000 every day. In the
United States in the year 1880, that is, the
year of the last census, over 91,000 persons
fell victims to this disease, and the average age
at death of these persons was thirty-seven.
Let him who has watched the progress of this
insidious disease in but a single case, imagine
if he can the misery and pain which these fig-
ures represent.

The disease is considerably less frequent in
some regions and countries than in others, but
everywhere where men live together in large
numbers, or live under bad sanitary conditions

62 DUST AND ITS DANGERS.

in-doors, this disease claims its numerous vic-
tims when once it gains a foothold.

Our attention is not ordinarily called to the
large numbers of persons who sicken and die
from consumption, because we have become so
accustomed to it that it is taken as a matter of
course, — one of the inevitable ills of life. When
yellow-fever or small-pox or Asiatic cholera
threaten to spread among us, we are on our
guard at once, and from the medical profession
and the press come such warnings that no
pains are spared in public or in private to stay
their progress. And yet the number of victims
of these occasional and dramatic epidemics is
quite insignificant as compared with those of
our omnipresent consumption.

We dread outbreaks of small-pox and care-
fully guard ourselves against its spread, but in
the State of Michigan, which is typical of
many others, in 1886-87 there were from forty
to fifty times as many deaths from consump-
tion as from small-pox. In the State of New
York in 1887 there were reported 96,453
deaths, and 11,609 of these were from con-
sumption.

DUST AND ITS DANGERS. 63

i

A glance over the mortality in various cities
in different parts of the world, as it comes to
us in the very latest reports, shows everywhere
the same story. We find in Dr. Tracy's report
to the Health Department of New York City
for the week ending March 22, 1890, that in
New York City, out of 772 deaths from all
causes, 121 were from consumption. In Chi-
cago, out of 2,072 deaths, 178 were from con-
sumption. In London, out of 1,889 deaths,
206 were from consumption. In St. Peters-
burg, out of 617 deaths, 128 were from con-
sumption. In Paris, out of 1,214 deaths, 248
were from consumption. In Vienna, out of 470
deaths, 116 were from consumption. In Berlin,
out of 650 deaths, 96 were from consumption.

These are the bald relentless records of the
deaths. But who shall adequately picture, or
even remotely conceive, the shattered ambi-
tions, the long weary hours of distress and
suffering and struggle, the slow weeks and
months, lighted fitfully now and then by gleams
of fictitious hope, which lead to the last long
release. And what shall be said of the deso-
lated homes and scattered families, and pov-

64 DUST AND ITS DANGERS.

erty and want and crime which among the
poor are wont to cluster about and to follow
such premature and lingering death ? Probably
the actual suffering and distress caused by all
other diseases put together is far less than
that which in one way or another is associated
with consumption.

Now where do all these people get this most
widespread disease ? How do they become
infected ? Where do the living bacilli of this
particular species come from which get into
their bodies ? They do not grow at the tem-
perature of the air out-of-doors. There are no
lurking-places for them in nature apart from
those men or animals who have the disease.
Plant them artificially with other common bac-
teria in tubes in the laboratory and they die ;
they succumb in the struggle for existence
with the harmless species of the earth and
water and air.

In a certain number of cases they no doubt
are taken in with the food, and inasmuch as
tuberculosis of cattle is a very common disease
all about us, there is every reason for believing
that the infection often enough occurs through

DUST AND ITS DANGERS. 65

the use of uncooked meat or milk. That the
consumptive mother may infect the nursing
child with its food has been abundantly proven.
There are cases in which the tubercle bacilli
get into the blood and are distributed to all
parts of the body, setting up such innumerable
foci of disease that the individual soon suc-
cumbs to the violence of the poison.

But after all, the prevailing seat of consump-
tion being in the lungs, the most natural
supposition is that the larger proportion of
consumptive people become infected through
the inhaled air.

Now, as has been absolutely proven over
and over again, in almost all populous regions,
both out-of-doors and in-doors, tubercular per-
sons may be discharging thousands of living
tubercle bacilli every time they spit out mate-
rial from their lungs upon the streets, or upon
the floors, or wherever it can dry and mingle
with the dust. If the tubercle bacillus is not
easily killed by drying, as has been fully proven,
have we not a sufficient explanation of the way
in which the infection of tuberculosis becomes
so widely and perpetually spread ?

66 DUST AND ITS DANGERS.

If this be true, — that tuberculosis is spread
by the breathing in of tubercle bacilli in the
dust of the air, then, it may be said, we ought
to be able to find these particular germs in
the dust of rooms inhabited by consumptives.
This is by no means an easy task, because our
means of identifying this germ are rather com-
plex, and require for their execution much time
and skill. But notwithstanding this, Cornet,
in Berlin, has over and over again, in the dust
high up on the walls of consumptive wards of
hospitals, in the dust of private houses, and
hotel rooms occupied by consumptive patients,
found living virulent tubercle bacilli. But he
found these only in cases in which the dis-
charged sputum was not carefully and at once
destroyed, but was permitted to lodge upon
floors or clothing or articles of furniture, where
it dried and finally became pulverized and car-
ried as dust to such parts of the room as are
not ordinarily cleaned.

Again, some one will say : " If it be true that
consumption is apt to be acquired by breathing
in of the bacilli with the dust, then we ought
to find in the lungs of persons who have died

RSITTJ

-~ DUST AND ITS DANGERS. 67

from other diseases not infrequently the com-
mencements of tuberculosis." Now this is in
fact just what we do find. It is very common,
indeed, to find in those little filters at the root
of the lung, — the lymph-glands which we have
spoken of in another chapter, — both in adults
and in children small areas of tubercular dis-
ease, and nothing else in the whole body indi-
cating the presence of the germ. The disease
here has not been extensive enough to cause
any ill effects or give any symptoms. It may
be in an early stage or it may have existed for
a long time, or it may have altogether healed,
leaving only its unmistakable traces behind
(see Fig. 6).

But more than this, even, we have learned
about the early stages of this disease. Dr. H.
P. Loomis has in several cases of accidental
death in apparently healthy persons examined
these lymph filters (lymph-glands), and found
them in appearance perfectly healthy, and yet
on applying one of the most delicate and effec-
tive tests, has found that after all they did, in
a considerable proportion of the cases exam-
ined, contain living tubercle bacilli. These

68 DUST AND ITS DANGERS.

were present, but had not yet set up even a
local disease.

It has been shown, by a careful series of re-
cent observations, that when due care and
intelligent cleanliness are provided for, the at-
tendants upon consumptives in hospitals and
in private houses, are not subject, in any
marked degree to the acquirement of the dis-
ease. But, on the other hand, it has been
equally fully proven that when proper cleanli-
ness is not exercised, and the expectoration of
the patients not intelligently cared for, the
attendants in hospitals for consumptives have
in very large proportion fallen victims to the
disease.

More proof than is in our hands is hardly
needed that in a very large proportion of cases
in inhabited regions the infection or germ of
tuberculosis is conveyed from sick to well per-
sons by means of the material discharged from
the lungs, which is allowed, from carelessness
or ignorance, to dry and finally mingle with the
floating dust.

While thus tuberculous persons may be a
constant source of danger to their healthy fel-

DUST AND ITS DANGERS.

lows, it is by no means true that they always
are or ever need to be. The breath itself, the

FIG. 6. — LYMPH FILTERS (LYMPH-GLANDS) AT THE ROOT OF THE
LUNG, THE SEAT OF LOCAL AND HEALED TUBERCULOSIS.

Two of the lymph filters at the root of the lung which have
become blackened from inhaled dust. But in addition to this, one
of them — the larger — shows two white spots which are caused by
the lodgment here of the tubercle bacilli. These germs, caught in
the meshes of the filter and thus kept out of the blood, have grown
here for a time. But owing to their growth or their presence, the tissues
about them have been so stimulated or irritated, that a dense organ-
ized wall has been formed around the germs, completely shutting them
off from the rest of the body. This is the way in which, the cure of
consumption is sometimes effected. Nowhere else in the body of this
person, who died from an acute disease, were there any evidences
whatsoever of tuberculosis-

70 DUST AND ITS DANGERS.

exhaled air of consumptives, no matter how
seriously ill, is not dangerous ; it carries no
germs. It is only the solid discharged mate-
rial of the sputum which carries the danger.
And this sputum, moist and usually adherent
as it is when fresh, is only dangerous, so far as
contamination of the air is concerned, when it
is permitted to dry.

Here we seem to be at the root of the evil.
The reason why consumption is so widespread
and the most important element in this appall-
ing mortality is simply that consumptive per-
sons, either from ignorance or carelessness, are
distributing the poison not only everywhere
they go, but everywhere the dust goes which
has been formed in part by the undestroyed
germ-laden material expelled from their lungs.
This is what has been mistaken for so many
years as evidence of the hereditary transmis-
sion of consumption, as proof that consumption
" runs in families." The house-mates have
unwittingly poisoned one another, usually, no
doubt, through the dust. We are but just be-
ginning to recognize this. We have, indeed,
known what caused consumption but a very

DUST AND ITS DANGERS.

few years, and even many intelligent physi-
cians are not yet sufficiently impressed with
the inexpressible importance of scrupulous
cleanliness in tuberculosis to urge it as they
should.

The way, then, to most efficiently stop the
prevalence of this distinctly preventable dis-
ease is evidently to see that the sputum of
consumptives is properly disposed of. When
this is practicable it should be received in
small paper cups,1 made for this purpose, and
as soon as possible burned. The reception of
the sputum upon fabrics of any sort is always
to be deprecated.

The reason why the use of cloths or hand-
kerchiefs for the reception of the expectoration
in consumption should be as much as possible
avoided is that on these the material very
readily dries, and, becoming detached with or
without the minute particles of fabric, readily
floats off in an inhalable condition into the air.
For the same reason, great care should be
exercised by consumptives to avoid the soiling
by sputum of woollen garments from which

1 These are now in the market and sold cheap by druggists.

72 DUST AND ITS DANGERS.

very fine fibre particles are always very
readily detached, and would carry with them
dried particles of germ-laden material, should
such have been allowed to fall upom them.

But if cloths must be used, as will often be
the case, either to receive the expectoration or
for wiping the mouth, they should be such as
can be as speedily as possible burned with
their contents. When handkerchiefs are used
they should be as early as possible boiled for a
full hour in a receptacle by themselves before
they are washed in the ordinary way. Cheap
paper cuspidores are now made which should
be placed in all apartments frequented by con-
sumptives, and frequently changed and with
their contents burned.

The greatest drawback in the suggestion of
such rules of procedure as would be efficient in
preventing the spread of tuberculosis is the
certainty that they will not, in a great many
cases, be followed. Persons who are cleanly
enough in private houses will spit upon the
street, or in public conveyances, or on the
floor of theatres and other places of assembly,
and until the knowledge that the sputum of

DUST AND ITS DANGERS. 73

consumptive persons may be dangerous shall
have become widespread, our efforts in the di-
rection of the prevention of this disease will
continue to be counteracted by the misdeeds
of the ignorant and careless.

Consumption is at best, if it has any best, a
most distressing and deplorable malady. But
when we have learned, as we have within the
last decade, that the chances of recovery are
often very good indeed ; that it is not hopeless,
as was formerly believed ; that it is not in-
herited ; when we appreciate that with due
care the stricken one need not in the least be
a source of danger to others, even to his house-
mates ; when we fully realize that the appalling
prevalence and mortality of the past has been
due to ignorance of the nature of the disease
and the mode of its transmission, we should be
able to appreciate how much we owe of com-
fort and of hope to the investigations in
scientific medicine, which have given us all
this, if they have not yet brought to us such
means as will directly cure the disease in
individuals when once firmly established.

CHAPTER IX.

DUST-DANGERS OUT-OF-DOORS AND IN PRIVATE

HOUSES, WITH SUGGESTIONS FOR

THEIR AVOIDANCE.

WITH all these facts about the most
common way in which consumption is
transmitted from one to another before us, we
are ready to consider what the places are in
which healthy persons are most likely to be
forced to breathe air which contains this or
other infected dust, and what should be done
to avoid it.

It should always be held in mind, in con-
sideririg the facts and suggestions which this
chapter contains, that the safeguards of the
body against inhaled germs, which we have
already looked at in another chapter, are
constantly in action, and in large degree, in
many persons, actually and wholly protect

74

DUST AND ITS DANGERS. 75

against danger, even in very dirty and very
infectious places. Many disease-producing bac-
teria soon die, in greater or less numbers, soon
after they are expelled from the bodies of sick
persons ; many are swept away by the winds
into uninhabited regions ; many fail to come
in contact under favorable conditions with
susceptible human beings. But these natural
safeguards cannot be implicitly relied upon
for safety by any one at all times, nor can
any one with impunity overtask their capaci-
ties by unnecessary and constant exposure of
his person to infectious dust.

It is certain that in the out-of-doors air in the
country, and also in cities whose streets are
kept decently clean, there is little danger of
harm from the inhalation of germs of con-
sumption or of any other disease, because the
constant purifying agency of wind and air
currents will either soon sweep away the dust
or so largely dilute it that it will be practically
free from disease germs, the sources of which
are so comparatively limited. If, however, the
streets of cities be or are allowed to remain
filthy, so that abundant and pretty constant

DUST AND ITS DANGERS.

dust-clouds are encountered by those passing
through them ; if the streets are not properly
sprinkled before sweeping, either by machine
or hand ; if ignorant or careless street-cleaners
are allowed to scatter clouds of dust about
them as they sweep or shovel or transport the
pulverized filth, the chances of inhalation of
dangerous dust particles are proportionally
increased. But, on the whole, the risk of
infection out-of-doors from dust, even in
crowded towns, unless they are notably filthy,
is not actually very great.

Indoors, however, the conditions are en-
tirely different. Let us first consider private
houses and living rooms. Here, as we have
already seen, the sources of micro-organisms
are various, but we need consider here only
those which cause consumption. These may
be brought in on feet and garments from the
streets or other places, or be blown in through
open windows or drawn in by other modes
of ventilation. If there be no consumptive
persons in the house or rooms, these chance
sources of infection are all that need be re-
garded. If there be consumptives in the

DUST AND ITS DANGERS. 77

rooms, no further danger need be feared if
the material which they expectorate be scru-
pulously attended to in the manner already
indicated. If, on the other hand, consump-
tives are permitted to discharge the material
raised from the lungs on floors or elsewhere
where it may dry, this will be a source of dan-
ger far exceeding all others. In houses where
healthy persons are, then, or in houses where
consumptives are who are intelligently clean
in their habits, the chances of inhaling the
tubercle bacilli are slight. But it should al-
ways be remembered that these chances,
whether small or great, are directly dependent
upon the means which are used to get rid
of the dust. If this be permitted to accumu-
late so that it is liable to be stirred up over
and over again by the movements of persons
in the room, by so much will the risks be
increased of inhaling the harmless germs of
dust and with them sooner or later, the dan-
gerous ones, should such by chance be present.
It is perfectly obvious that unless the win-
dows be widely open or liberal air currents in
some way established, the too common method

78 DUST AND ITS DANGERS.

of so-called " dusting" — that is, the stirring up
of the dust which has settled on the smooth
places in a room so as to allow it to settle
again on to the rough surfaces or inconspicu-
ous places where it does not show — is worse
than useless, since the dust and germs are not
in this way got rid of, but only redistributed
and put for a time in a situation suitable for
inhalation.

Carpets and heavy hangings and upholstery
with rough goods all insure the more or less
persistent retention of dust particles in rooms
and with these the harmful germs, if such are
present.

Hard floors, with rugs which may be cleaned
out-of-doors, as few and as light hangings
as are practicable, furniture upholstered as far
as may be with smooth-surfaced fabrics, the
use of moist dusting-cloths, and the wide open-
ing of windows and doors when cleaning is
going on, — these are the general suggestions,
which, if followed, will confer in a large degree,
even in populous towns, a sense of security
against the dangers of dust in private houses
in which healthy persons live.

We need here only call attention in the

DUST AND ITS DANGERS.

briefest way to many devices in the lore of
the enlightened housekeeper for cleaning of
carpeted floors without raising clouds of dust
which seem more objectionable the more we
know about them. Such practices as the sprink-
ling of carpets with coarse salt, or salt and bran,
or moist tea-leaves, or other substances which
keep down the dust : the use of some of the
more perfect forms of carpet-sweepers, etc.,
may be brought to bear in solving the prob-
lem of clean living places in towns.

The writer can perhaps imagine the fine
scorn with which his meek suggestions in this
direction may be met by the experienced
housekeeper, and indeed makes no virtue of
insisting upon method so long as the removal,
and not the simple redistribution of the dust,
be the end accomplished.

In houses and larger buildings which are
supplied with a system of forced ventilation, or
wherever the ventilation-draught is strong
enough, a great deal may be accomplished in
the way of keeping the dust out of the buildings
by the use of cheese-cloth or thin cotton batting
screens placed across the air currents near the
entrance of the ventilation-shafts.

CHAPTER X.

DUST-DANGERS IN PUBLIC BUILDINGS AND PUBLIC
CONVEYANCES.

WE come now to another class of places
in which dust is a matter for very seri-
ous consideration. I mean theatres, churches,
schools, and court-rooms and other places of
assembly in-doors where large numbers of per-
sons are frequently crowded together. Here
the individual in the matter of the cleanliness
of the air he breathes is largely at the mercy
of his fellows, and especially of the persons
too often ignorant and careless to whom is
intrusted the more or less frequent sweeping,
dusting, or other cleaning of the rooms.

So prevalent is consumption, and so insidi-
ous in its onset that there are very few large
assemblages in which some victims of the dis-
ease are not present. Such persons, if not

80

DUST AND ITS DANGERS. 8 1

informed of the danger of the practice, will be
apt to convey some of the material discharged
from the lungs to situations in which without
care and vigilance on the part of those who
afterwards clean the rooms, it may form a part
of inhalable dust.

Many of the theatres are probably the most
likely places of any which we know frequented
by healthy persons in large cities for the inha-
lation of disease germs of one kind or another,
especially the germ of tuberculosis. The ven-
tilation is usually wholly inadequate even for
the purpose of carrying off the vitiated air of
respiration or exhalation, and is of almost no
use in freeing the air of dust. Close walled
they are apt to be, so that large volumes of
out-door air rarely or never sweep through
them, carpeted and the chairs upholstered in
plush, visited by large numbers of all kinds of
people who, in the long sittings, pretty gener-
ally thoroughly cleanse their shoes on the
carpets, if they do not add to this their sali-
vary contributions. The floating particles ac-
cumulate in theatres in enormous quantities,
in such quantities, indeed, that the tell-tale elec-

82 DUST AND ITS DANGERS.

trie light beams show a blue or gray cloud on
most occasions where they pierce the dust-la-
den air. Now, it is a fact that in most theatres
at least there is no efficient means made use
of to get this accumulating dust out of the
auditorium. The coarser dirt is swept up
more or less frequently in all of them, and
carried off, but the finer dust is usually simply
stirred up again in a perfunctory and wholly
useless way from the seats to settle back again
into the plush or the carpets, to be stirred up
anew by the incoming and outgoing audience.
The fact is, the upholstering of the chairs of
public assembly-rooms ought never to be done
with plush or other rough fabric which catches
and holds the dust. The floors should not be
carpeted, as there are plenty of other whole-
some substitutes, and both the ventilation and
the daily cleansing ought to be done under
some intelligent direction, so that these places
need not continue to be, as so many of them
now are, veritable death-traps and distributing
centres of bacterial disease. While there are,
of course, exceptions to the condition of affairs
which has here been described, the exceptions

DUST AND ITS DANGERS. 83

are not by any means always or usually the
more fashionable or popular theatres.

This matter of enforcing reasonable cleanli-
ness in theatres and other places of assembly
rests, as all other matters of sanitary reform
ultimately do, with the people themselves. So
long as the patrons of filthy theatres, either
fashionable or not, permit themselves to remain
the victims of ignorance or carelessness or cu-
pidity the managers of theatres will doubtless
continue to do just what they have been doing
and are doing, no matter what in their prac-
tices is shown to be dangerous.

Whoever has had occasion to visit the court-
rooms in the city of New York — and similar
conditions are widely prevalent in court-rooms
as well as legislative halls elsewhere in this
land — cannot fail to have been impressed with
the general filthiness and dustiness and stuffi-
ness which is so pronounced. With the evils
which vitiated air causes all are more or less
familiar, but to these evils even the large intel-
ligence of the members of the legal profession
usually supinely submits. That poisoned dust
should be added to the burden simply because

84 DUST AND ITS DANGERS.

there is no general protest against the careless-
ness or ignorance which is displayed in the
so-called cleaning of these places, seems almost
incredible when the importance of the matter
is once realized. In the same deplorable con-
dition are many of the public school-rooms in
both large and small towns. Ventilation is
slowly becoming recognized as important, but
the removal of dust, which in crowded places
is very liable to be infectious, is not systemati-
cally attended to.

Public conveyances into which, especially in
this country, people are huddled indiscrimi-
nately, are very rarely properly cleaned and
dusted. Of course, in these it is not the ordi-
nary inorganic dust, the fine coal or iron or
sand particles which are most to be dreaded,
but the materials which come from uncleanly
travellers who are the victims of bacterial dis-
ease. The dangers will be removed only when
the travellers themselves realize that the dis-
gusting and very prevalent habit of spitting
upon the floor of public conveyances is not
only filthy but may be positively dangerous,
and the managers of the transportation com-

DUST AND ITS DANGERS. 85

panics see to it that their conveyances are
actually frequently cleaned.

A railway-car which comes in from its hun-
dred-mile trip is, when vacated by its occupants,
usually an extremely filthy place ; dangerous
even, if by chance it has borne an uncleanly
passenger afflicted with bacterial disease. And
yet, as every observant person who travels
much has often seen, these cars may be started
out on the return with their full loads of fresh
victims, after no other cleaning than a few
random broom-sweeps and a few flips of the
feather-duster over the window-seats and plush-
covered chairs — the windows usually tightly
closed meanwhile, and the doors, possibly, but
by no means always, opened.

But here again, if the travelling public will
not protest against the filthiness of many pub-
lic conveyances, and insist upon a more intel-
ligent and careful system of cleaning, matters
will probably remain as they are. Where com-
petition exists between the transporting com-
panies, persistent public protest will in the end
be heeded. Where competition does not ex-
ist, woe to the traveller.

86 DUST AND ITS DANGERS.

Sleeping-cars and the state-rooms of steam-
ships and hotel bedrooms are almost always
liable to contain infectious material, if they
have been recently used by uncleanly consump-
tives or those ignorant of the danger of their
expectoration. When the infectious nature of
consumption becomes more generally appre-
ciated, hotels and transportation companies
over long routes will be compelled to provide
special accommodations for such persons as
are known to be thus afflicted. In the mean-
time, more careful attention to the cleaning
and dusting (that is actual removal of dust)
of such places will do much to mitigate the
evil. In public buildings with bare floors the
use of properly-wetted sawdust, sprinkled over
the floors before sweeping, should be more
generally followed than it is.

CHAPTER XI.

SOME OBJECTIONS, PROTESTS, AND QUERIES
ANSWERED.

MANY usually very reasonable persons,
when brought face to face with such
disagreeable facts as have been here set forth,
are disposed to petulantly exclaim that they
and their friends have got along very well thus
far with the dust which they have encountered,
and that they don't want to be worried with
the possibilities of danger which may lurk un-
seen about them. The world's people, they
say, have managed to live along in large num-
bers for a good many centuries without know-
ing any thing about the bacteria which may be
sporting in this excellent canopy, the air.

To these rather short-sighted and impatient
expostulations it may be answered : The fact
still remains that about one out of seven of

87

88 DUST AND ITS DANGERS.

all the people who die are prematurely carried
off by tuberculosis, and a large proportion
of these through dust-poisoning, which if we
choose we can largely prevent. We are apt
to forget that, as soon as we know the cause
and the means of prevention of a disease like
consumption, the responsibility for a large
death-rate is no longer to be laid to the charge
of Providence or fate, but at the door of human
ignorance or carelessness. We are apt to for-
get, too, that such dangers from uncleanly air
are constantly increasing with the crowding
together of large numbers of people in cities,
and especially in cities in which the manage-
ment of municipal affairs is in the hands, not
of intelligent and honest men, but of political
tricksters and unjailed thieves.

We pay the penalty of the close huddling to-
gether of large numbers of people in cities, by
the increasing vigilance which we must exer-
cise to prevent the spread of infectious disease.
We may deplore the necessity for such homely
and incessant painstaking as is imperative if
we would keep our living-places clean and
wholesome ; we may carp and cavil at sanitary

DUST AND ITS DANGERS. 89

preachments if we will, but we ignore them at
our peril. Rich or poor, high or low, ignorant
or learned, all are alike liable to become the
victims of such diseases as are spread in the
floating dust of ill-kept towns and dust-ridden
houses.

If the prevention of the spread of consump-
tion were a matter which could be carried out
by physicians alone there would indeed be
little use in inciting a general apprehension of
the dangers of dust-poisoning. But, unfortu-
nately, this is not possible. If we are, in any
large degree, to limit the ravages of consump-
tion, and with it the evils of many other bacterial
diseases, this must be done through the thor-
ough understanding of the danger and its
nature by the people at large, and the practice
of proper cleanliness in the houses which
they directly control, and also by forcing clean-
liness upon the managers of public places,
which in the end they also ultimately control
through public opinion.

If it be not worth while to save one out of
every eight or ten or one hundred or one thou-
sand from the distress and pain and misery of

90 DUST AND ITS DANGERS.

the consumptive's lot, then such considerations
as have been urged in this book are worse than
useless. But if, on the other hand, the moder-
ate care and attention to cleanliness in the places
in which we live or which we frequent is but a
small price to pay for the large immunity from
disease which would surely follow, then the end
in view would seem fully to justify any pains
which we may take to make and keep our
living-places clean and wholesome.

Many are disposed to assume that in towns
whose affairs are administered by dishonest or
careless officials the task of cleanliness in
houses is a nearly hopeless one, and this, in a
measure, is true. But we are too prone, in
this country, to permit ourselves to be imposed
upon in countless ways without protest, and
with a supineness or indifference which is little
short of disgraceful.

There is probably no city or town in the
United States which need be either misgov-
erned or filthy, if only the respectable people
would intelligently unite in the assertion of
their rights. In the matter of dust and street
dirt, in which regard the city of New York is

DUST AND ITS DANGERS. 9!

in such a desperate case, much more is in-
volved than individual right or personal com-
fort. We virtually condone manslaughter just
as long as we permit men to hold municipal
offices who fail in their plain duty in the
protection of the public health. From mayor
to scavenger they should be held personally
responsible, and no political chicanery per-
mitted to obscure or call away public attention
from the business which such persons are
appointed and paid to attend to. We owe a
great deal to the vigilance of the press in
calling attention to sanitary abuses, but with-
out the steady and persistent urgency of
individual protest this is of but little avail.

Until the recent revelations in bacteriology
gave us firm ground to stand upon in forming
our conceptions of the cause of contagious and
infectious diseases, there was something most
mysterious and dreadful, and the more uncanny
because mysterious, about the agency which
could so subtly convey a dreaded disease from
one to another. That invisible thing which
could linger about a room or cling to a folded

Q2 DUST AND ITS DANGERS.

garment for weeks or months — which could
pass unseen through the air and work desola-
tion far away — was something which might
well inspire awe, if not superstition.

To-day, however, the whole aspect of affairs
has changed. We have at last found out that
these subtle agencies in the diseases of this
class which have been most fully studied, are
well-defined organisms which we can isolate
and cultivate and study, small as they are, with
as much precision and certainty as we can
cabbages and pumpkins. We know a great
deal about the conditions which favor their
growth, and various things which, at least
outside of the body, will kill them and render
them harmless.

With this definite knowledge about some of
the agents (bacteria) which cause disease, the
most impenetrable of the mysteries clustering
about the infectious diseases have passed away.
For while we do not yet know, as we have seen
in another chapter, the exact form or species
which is concerned in causing all of the dis-
eases of this class, we have indisputable
ground for assuming that they all are caused

DUST AND ITS DANGERS. 93

by some formed, minute, living thing, either
plant or animal. This leads us to the further
definite conclusion that whenever one of the
contagious or infectious diseases is conveyed
from one person to another, this is done by
formed material which must pass frpm one to
another, either in the shape of palpable solid
matter or by fine floating dust-particles.

Now, when we interpret this rather long
exposition of facts and inferences into every-
day experience, we find that it means some-
thing like this : When we have in the house
a victim of one of the infectious diseases, such
as diphtheria or consumption, and want to
protect the house-mates against it, both while
it is active and after it is over, we no longer
grope after some mysterous, intangible thing,
before which we must bow down or burn
something, as if it were some demon which we
would exorcise. We say to ourselves, if we
can at once destroy, by boiling it or burning it
or soaking it in some suitable disinfectant, all
the material which is discharged from the
patient's body, he will cease to be a source
of contagion — the poison cannot spread from

94 DUST AND ITS DANGERS.

him. When the illness is over and we disin-
fect the rooms, we aim not to drive out any
malign spirit, any mysterious kobold lingering
in the air, but we are trying to kill the bacteria
or other similar organisms which may have
escaped our vigilance during the disease, and
in more or less solid form or as floating dust
have found lodgment on bedding, furniture,
garments, or on walls or hangings. In all the
management of the sick room, in all we do for
the person of one suffering from an infectious
disease, this is the conception which we should
cherish as to the source of danger.

Most likely many will say, in view of what
has been set forth in this little book about the
transmission of the germ of consumption by
floating dust : " Why do we not all catch con-
sumption, if, as he says, it is contagious ? We
should be very apt to catch small-pox or
scarlatina if brought in contact with them. It
can't be true that consumption is contagious."
To this it may be answered that some of these
diseases are much more readily communicated
than others are from person to person. Thus
scarlet-fever and measles and small-pox are

DUST AND ITS DANGERS. 95

much more readily transmitted than is diph-
theria or consumption ; they are, as we say,
more highly contagious, and although we do
not yet exactly know what form of germ causes
scarlet-fever and measles and small-pox, we are
pretty certain that they are caused by germs
or lowly organisms of some kind, and that
these are much more readily or freely given
off from the body than are the germs which
cause less easily communicated diseases, such
as consumption and diphtheria, and are more
liable to exist in the form of particles which
float in the air as impalpable dust.

Then, again, we should not lose sight of the
fact that the germ of consumption is a very
slowly-growing germ ; that only under a very
limited range of conditions does it grow at all,
and that after all the chances are not very
great for each one of us that from aerial con-
taminations a sufficient number of the living
bacilli, even if breathed in and passing all the
safeguards of the body against such intruders,
at last find lodgment in the tissues, will find the
conditions favorable for a sufficient growth to
induce the disease. Now and again only does

96 DUST AND ITS DANGERS.

the favorable combination of conditions occur,
but — and let this be noted well — the nows and
agains are frequent enough in the aggregate to
secure for consumption the distinction of being
the most common and serious, as it is the most
distinctly preventable, disease known to man.

It might be thought that if we know what
form of germ causes a given infectious disease,
and what chemical substance or drug will kill
it, we could readily control the disease when
once established in the body by giving a medi-
cine which would kill the germs. So we could ;
but unfortunately the whole body is made
up of little masses of living matter, which
we call cells, and these are about as readily
killed as bacteria are by the drugs which we
should like to use for this purpose. So that in
killing the germs we should be apt to stop the
disease indeed, but kill the body too.

We hope sometime, as has been already
said, to find some sort of agency which will
kill, or render harmless, the germs which cause
infectious diseases without harming the body.
But in the meanwhile, and perhaps always —
since the Irishman's conduct in swallowing

DUST AND ITS DANGERS. 97

a potato-bug and then swallowing Paris green
to kill it was not very rational — we must do
the best we can along the lines which have
been suggested in this book to prevent the
occurrence of these diseases by destroying the
germs before they get scattered in the dust, or,
failing in the opportunity for this, see to it
that the dust itself is intelligently disposed of.
One of the most serious obstacles in the way
of clean living in towns in this country is the
especially American expectoratory prerogative,
which so frequently both anticipates and ac-
companies the franchise in otherwise decent
males. The trick is early acquired by our
mongrel immigrants, who lose no time in bet-
tering our instructions. Could women, walking
upon our streets, leaving cars, and descending
from elevated railroad stations, but see them-
selves and their environment as others see
them, the management of the skirts of walk-
ing-suits would, it would seem, command from
them a more careful attention. We must
speak plainly here, for very surely unto dust
does all this expectorated unspeakableness
soon return.

7

98 DUST AND ITS DANGERS.

The spectacle of the well-dressed, filthy
brutes, whom natural selection has most un-
kindly left but a few degrees higher than their
congeners in the sty, wallowing in their ex-
pectoration, about certain hotels and theatre
entrances, may well impress the sensitive on-
looker with the colossal task which Nature
undertook when she set to work to evolve
man, and the lamentable failures which are so
often but half-concealed in fashionable attire.

CHAPTER XII.

SUMMARY AND CONCLUSION.

IF, now, we sum up the main points which
have been urged regarding the ordinary
mode of transmission from one to another
through the air of the germ of consumption
and the means of avoiding it, we see, in the
first place, that the most complete remedy of
existing evils is simply the immediate destruc-
tion of the material discharged from the lungs
of affected persons ; second, the practice, both
in private houses, in places of assembly, and
in public conveyances, of more intelligent and
efficient systems of cleaning, and particularly
the adoption of appropriate means for getting
rid of the floating or settled dust.

The dust of ordinarily clean public rooms
and of private houses is not, as we have seen,
dangerous or especially harmful unless it has

99

IOO DUST AND ITS DANGERS.

among its ingredients the living germs which
have come from the bodies of persons suffering
from bacterial disease. This dangerous ad-
mixture in dust is always possible in populous
towns, and while the danger from this source
is in general not very imminent, it is increased
in direct proportion to the accumulation of dust
which is allowed to occur either in private
houses or places of assembly.

Two important means exist for getting rid
of dust either in private houses or in places of
assembly or public conveyances. The first is
to sweep and to stir up the dust with windows
and doors wide open, so that the temporarily
floating particles may be largely carried out-of-
doors, where they will be soon diluted and swept
off. It should, in the second place, be borne
in mind that in still rooms the dust, and with
it the larger part of the aerial germs, will
settle, within a few hours, so as to leave the
room almost entirely free from them. If, now,
the mopping of the floor or the dusting of furni-
ture with moist cloths be practised, the larger
part of the dust may be completely removed
from the rooms. The completeness of this

DUST AND ITS DANGERS. IOI

removal will, of course, depend largely upon
the simplicity of the furnishing and the intelli-
gence which is used in the work. The relega-
tion of the work of sweeping and dusting of
rooms to ignorant and careless servants, with-
out intelligent and persistent supervision, can-
not be expected to result in clean living-places.
We realize more fully now than ever before,
weighing the accumulated experience of years
in the light of the new knowledge about the
cause of consumption, that this disease is by
no means always a hopeless or fatal one.
Many persons get well, and many more so far
recover as to enjoy years of comfortable life.
We do not yet know any particular drug or any
especial medical treatment which can be depen-
ded upon to cure consumption. But we do know
that, by putting the body under certain favor-
able conditions — proper food, suitable climate,
appropriate regimen, and aiding these, when
occasion requires, by drugs, — the physician can
often hold out to his patient this well-grounded
hope, that the body's natural safeguards against
the invasions of bacteria reinforced in this way
may lead him to recovery and a new life. But

102 DUST AND ITS DANGERS.

this lesson, first of all, the patient should learn,
that he must see to it that all expectoration be
destroyed, or else he is constantly running the
risk of reinfecting himself, and thus destroying
his chances of a victory over the disease, and
is, moreover, exposing others to a serious risk
of acquiring it.

The establishment of special sanitariums in
the country where consumptives may be intel-
ligently cared for is not only of great benefit
to the stricken individuals themselves — giving
them, as a rule, the best chances for recovery,
— but is of incalculable importance to commu-
nities at large, since it removes an important
and, as we have seen, often active source of
dissemination of the disease.

It has not seemed to fall within the scope of
this little book to give detailed directions as to
the most efficient means of destroying infec-
tious material in the sick room nor the modes
of disinfection of such rooms when the disease
has passed, because these are matters which will
always be attended to by the physician if he be
intelligent and well informed, and must vary
more or less with the conditions of each case.

DUST AND ITS DANGERS. 103

A little thoughtful consideration of the facts
and principles which have been set forth can-
not fail to result, under ordinary circumstances,
in an improved sanitary condition of the places
in which we so largely spend our lives.

We are just entering upon a new epoch in
our knowledge of disease. The discovery of
the bacterial origin of so many of the infectious
diseases, which have hitherto been as myste-
rious as they were fatal, has placed us on a
higher plane, so that there is a good hope that
in the not distant future we may not only in
large degree limit the spread of these diseases,
but even learn some reliable means of cure for
them. We have in our hands to-day as we
have seen the means of prevention in large
measure of consumption provided the simplest
dictates of cleanliness be followed and the same
may be said of typhoid-fever, diphtheria, ery-
sipelas, blood-poisoning, and several other in-
fectious diseases.

It is because medical science is raising itself,
in the light of our new knowledge, to the higher
plane of the general prevention of the infec-
tious diseases, that we are hearing so much

104 DUST AND ITS DANGERS.

nowadays about bacteria and germs and infec-
tion and the need of a more intelligent
cleanliness.

It is not a mere fashion at whose dictates
the doctrine of cleanliness in person, food, and
air is being so widely and earnestly proclaimed
to-day. It is no fad of the hour which is to pass
and be forgotten. If our research into the
sources of widespread human ill does carry us
down into the realm of the invisible world we
bring from it such knowledge as is full of
significance and rich in the promise of human
weal, if we do but heed the lessons which are
already clear, precise, and not easily to be
mistaken.

INDEX.

PAGE
Air, amount of, used for biological analysis . . . . .23

" analysis, biological, methods of . . . . . 13, 19

" filtration method of . . . .15

" plate method of ..... 15-18

11 bacteria of , as disease producers . . . » . . 52, 53

" contaminated by tubercle bacilli in dust of . . . . .66

" effects of stirring of, in altering germ contents . . . -31

" " sweeping on ....... 31-33

" exhaled, freedom of, from dust and germs . . . . .69

" filtration of, in ventilating shafts ..... .79

"• in-doors, bacteria in ........ 33

" " dangers of, from floating dust . . . . .76

" " germs in ..... ,~ . -. . 27

origin of germs found in . . . . 30

" " spontaneous freeing of, from dust and germs . . . 27

" varying number of germs in . . ..... 34

I modes of spontaneous freeing of, from dust and germs . . .31

II of theatres and other public places as sources of disease . ^. .81
1 out-doors, varying number of germs in . . ... .22,23

14 " spontaneous freeing of, from germs . . * . . 21

k probability that consumption is commonly transmitted through . 65

41 street-, in cities, dangers of, from its floating dust . . • 75

" " in New York during cleaning ..... 25, 26

Antaeus ..... . . . . 16

Asiatic cholera ......... 55

Bacilli ......*... 13

" -tubercle ......... 48

dangers from, in sputum of consumptives . . .61

habitat of . . . . . . .64

in bodies of apparently healthy persons . . .67

" dust of rooms used by consumptives . . .66

105

106 INDEX.

PAGE

Bacilli-tubercle, mode of action of, in producing consumption . . 60

Bacillus of tuberculosis . . . . ... .59

Bacteria, colonies of . . . . , , 12

definite knowledge of, as explaining many mysteries of disease . 92
disease-producing . . . . ... • ^3

forms of . . . . . . . , 7

in air as disease producers ...... 52

" in-doors dust ........ 27

" out-doors dust . » . . . . . . .21

mode of determining number of, in air . . . . 13

modes of disposal of, in the body when inhaled . .46

" formation of dust from ..... 8

modes of study of » « ; . . . n

nature of . . . ...... 7

occurrence of, in nature • •-• . . . . . 8

relations of, to infectious diseases ••'. . . . . 55

significance of, in air in general . . . . . 20

Bacterial-diseases, remedial agents in . . . . .96

Bacteriology as throwing light on disease . . . . .91

Berlin, air analyses in ^ ....... 23

Biological air analysis . ^ . . . . , yg

Blood-poisoning . ,• . . . . . . '55

Boston, air analysis in . . . . . . . .23

Burning, best mode of destroying germ-laden sputum in consumption . 72

Carnelly, air analyses by ........ 23, 33

Catarrh, relations of dust to ....... 52

Cells, ciliated, in air tubes ....... 38

Central Park, N.Y., analysis of air in . . . . . .25,26

Cleaning of rooms . . . . . . . 82, 86, 100

Cleanliness, importance of, in living places . . . . .90

Cloths, dangers of use of, to receive tubercular sputum . . .71

College of Physicians and Surgeons, N. Y., air analysis at . . -33,34

Consumption ......... 56

a preventable disease . . . . . > 57

heredity of . . . . . • •'••• 59

importance of, as compared with other diseases . . 62

insidiousncss and slow beginning of . _ » . . 57

mode of transmission most common . . •» . 64

mortality from, in various cities . . . ... . 63

most direct means of preventing spread of . . .71

not always a hopeless disease .... 73, 101

INDEX. ID/

PAGE

Consumption not one of the highly contagious diseases . . .94

of the lungs the most common form of tuberculosis . . 65

predisposition of certain persons to . . •' • 59

prevalence and mortality of . . . . . 57, 61

proper food and surroundings more important than drugs in

the treatment of . . . ... 101

spread by meat and milk . . . . .64

summary of the reasons of prevalence of . j .. . 70

transmission of, in unclean sleeping-cars, bedrooms, and

steamships ._••.. . . .'-»•.. 86

transmission of, to attendants upon the sick . ... . 68

tubercle bacilli the only direct cause of . . .* . 59

ways in which it is spread by dust . . . .58

Contagion .......... 93

Contagiousness, degrees of, in bacterial diseases . . . .94

Cornet, discovery of tubercle bacilli in consumptives' rooms . . .66

Cotton filters for bacterial air analysis . . . . .' . 14

Court-rooms, filthy and dangerous air of . . . »• . 83

Crime, toleration of filthy cities by the people a . . » . 91

Culture medium for germs . . . . % .• . 14

u methods for germs . . . . ... .11

Destruction of discharged material best means for preventing spread of

bacterial diseases . . . .-• .99

Diphtheria ....... • • 55

Disease, preventable . . . . ~\ .• . .54

44 relation of dust to . . . . . . .50

Diseases, infectious . . . . . f . -55

44 " presence of bacteria in explaining many mysteries of . 91

" relation of bacteria to . . . . • 55

44 of occupation . . . . ... .5

Disinfection, modern notions of, more precise . . . . . 93

Drugs in infectious diseases . . . . . .96

Dundee, air analysis in . . . . . . .23

Dust, as means of spreading consumption or tuberculosis . . .58

44 " source of danger in public assembly rooms . . . .81

44 coal- and cotton- ........ 4

44 dangers of, in public buildings ...... 80

44 -dangers out-doors and in-doors ...... 74

41 definition of . . . . . . . . .a

44 filtration of, out of lymph in the lungs ..... 45

44 in-doors, germs in ,~~ — ....... 37

108 INDEX.

PAGE

Dust, harmful effects of, on the eyes ...... 52

" in inhaled air, disposal of, by body . . . . -37

41 4k public conveyances . . . . . . .84

44 " theatres, or as means of conveyance of disease . . .81

44 " railway carriages as source of danger . . . . .85

44 in-doors, danger of infection from ...... 76

44 inorganic elements of ....... 4

" " as causes of disease . . . .51

44 lodgment of, in tissues of lungs ...... 44

44 materials composing ........ 3

44 metallic ......... 4

11 mode of occurrence of bacteria in . . . . . .8

44 nature of, in general ........ i

44 organic or living elements of ...... *f

44 out-of-doors, micro-organisms in . . . . . .20

44 relations of, to catarrh . . . . . . .52

44 removal of, from houses ....... 77

44 safeguards of body against ....... 36

44 settling of, in-doors ........ 22

44 significance of, in causing disease ...... 50

1 sweeping away of, by ciliated cells ..... 39

41 street-, dangers of infection from ..... 75

44 tenacious clinging of, to fabrics ...... 29

tobacco- . ........ 5

41 tubercle bacilli in. . . . . . • .66

44 two modes of freeing air from ...... 100

14 woollen .........5

justing .......... 78

Elevated R. R. in New York as source of annoyance and danger from dust 52
Erysipelas .......... 55

Evolution, failure of, to eliminate the porcine element in street loafers . 98
Expectoration as a common vice . . . . . .97

44 dangers of, in consumptives . . . . .61

Eyes, harmful effects of dust on . . . . . . .52

Filters, air-, in biological air analysis ...... 13-15

" dust-, lymph-glands in lungs as . . . . . .46

Filthy cities, no necessity for ....... 90

Filtration method of air analysis ....... 15

General knowledge, necessary to prevent spread of bacterial diseases by dust 89
Germs, aerial modes of study of . . . . . . . 11-13

INDEX. 109

PACK
Germs in in-doors dust ........ 27

41 in out-doors dust . . ... . . . .20

44 colonies of. . . . . . . . .12

41 nature of.. .......7

44 origin of, in in-doors air . . . . . . .30

44 safeguards of body against aerial ..... 36

Hotel bedrooms as sources of dust-infection . . . r. • . 89

House furnishing as affecting the risk of dust-infection . . .78

Immunity of body to disease germs ...... 49

In-doors air, analysis of ........ 27-35

Infection, dangers of, from street dust ...... 75

44 degrees of readiness of, in different diseases . . .94

Infectious diseases ......... 55

44 remedial agents in . . . . . • .96

Isolation of the sick as means of prevention of bacterial diseases . . 54

Lungs, most common seat of tuberculosis . ... . 65

44 pigmentation of, by inhaled dust . . . . .44

Lymph, filtration of, in the lungs ...... 45

Lymph-glands as dust-filters ....... 46

localized tuberculosis in . . . . . .67

Measles . . . . . . . . » . 55, 94

Meat, tubercular, as food, dangers of . . . . i . 64

Michigan, frequency of consumption as compared with small-pox in . 62

Micro-organisms in in-doors dust ....... 27

44 '4 out-doors dust . . * . . ' . .20

nature of ........ 7

44 safeguards of body against . . '. . .36

Milk from diseased cows, dangers of ...... 64

Motes in the sunbeam ........3

Moulds .......... 7

Mould-spores in air analysis ....... 18

44 *4 dust ........ 9

44 preponderance of, in wet weather . . . . 22

Neumann, air analysis by . .......33

New York, air analysis in . . . . . . . . 23-26

44 l4 filthy streets of ....... 21

Official negligence no excuse for private indifference to cleanliness . .90

1 10 INDEX.

PAGE

Petri's air analysis . . . . . . ....23

Phagocysts . . . .••'•' . . . 40-42, 48

Phlegm, removal of, by ciliated cells ...... 40

Plate method of air analysis ....... 15-18

Pneumonia ..........55

Predisposition to consumption . . % • , . « . .59

Preventable diseases . . . . . . . .54

Prevention of disease, a public and private duty . . . .88

li li " more reasonable than neglect and attempts to cure . 96
Public conveyances as sources of danger from infectious dust . « .84

Railway carriages as sources of danger from dust . « r • . 85

Rain, effects of, on number of aerial germs . . . . . 22

Reinfection of tubercular persons by expectoration . . . . 102

Rooms as repositories of dust and germs . . . . . .-"-99

Safeguards of body against dust and germs . . . . . 36, 75

Sand filters for biological analysis ...... 15

Sanitariums for consumptives ....... 102

Scarlatina . . . . . . . . . . 55, 94

Scavenger cells . . . . . . . . .41

School-rooms, dust in • . . . . . .84

Sleeping-cars as sources of infection . . . . . . 86

Small-pox . . . . . . . . . 55, 62, 94

Snow, effects of, on aerial germs ....... 22

Spitting-cups for consumptives . . . . , . 71

Spitting, dangerous and filthy nature of . . . . . . 72, 97

Sputum, dangerous nature of, in consumption . . . . . 60, 66

" proper means of disposing of, in comsumption . . .71

Steamships, state-roonis of, as sources of danger . , . . 86

Stein, experiments of, on floating dust . . . • '* .28

Sugar-felters in air analysis . , » . . • , 15

Sweeping, effects of, on aerial germs in rooms . . , , . 31-33

Theatres, dusty, dangers of , . . . . . . .81

u responsibility of the public for filthiness of . . . .83

" vicious methods of cleaning of ..... 82

Tubercle bacilli 48

" " growth of, in the body only under favorable conditions . 95

" habitat of • . « . . . v« . 64

41 " how spread in the air . . . . .64

** " in dusty rooms occupied by consumptives . » - . 66

INDEX. 1 1 1

PAGE

Tubercle bacilli in expectoration in tuberculosis of lungs . . .60

" " " the bodies of apparently he ilthy persons . . . 67

" " mode of action in causing consumption . . .60

" " not easily killed by drying ..... 65

u " spread of, by diseased meat and bad milk . . .64

44 " the sole direct cause of consumption . . -59

ki " vulnerability of, when growing with other germs . . 64

Tuberculosis . . . . . . . . . • 55^ 56

44 bacilli of, mode of action in causing . . . .60

44 frequency and mortality of ..... 61, 62

heredity of . . . . . . • -59

44 in other parts of the body than the lungs . ,. . 60

44 localized . . . . . . • .67

mode of transmission of . . ... ... 64

44 predisposition to- . . . • • . -59

41 spread of, by meat and milk ..... 64

4 "' " " dust 58

Tucker, air analysis by . . . . . . • . 23, 31

Typhoid fever . . . . . . . • • 55

Ventilation, effects of, on floating dust . . . • • 28

Vigilance necessary to prevent spread of bacterial diseases . » .88

Webster's definition of dust . . . . . »,.2

Wind, effects of, on floating dust and germs ..... 22

Yeasts .... ..... 7

Yellow fever ........ -55

THE END.

Y.B 65690