The story of the bacteria and their relations to health and disease

LIBRARY

OF THE

UNIVERSITY OF CALIFORNIA.

Class BIOLOGY

LIBRARY
G

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

DIRECTOR OF THE PHYSIOLOGICAL AND PATHOLOGICAL LABORATORY

OF THE ALUMNI ASSOCIATION OF THE COLI-EGB OF

PHYSICIANS AND SURGEONS, NEW YORK

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EXPLANATION OF THE PLATE.

FIG. I. — A large mass of bacteria growing in a tube on a trans-
parent culture medium. This species is called Micrococcus luteus,
(page 40) and is a " pure culture " (page 35).

FIG. II. — A gelatin plate culture (pages 36, 37, and 38), showing
several colonies of different species of bacteria growing in the thin
layer of solidified gelatin. Each colony is composed of thousands of
individual bacteria. (See Fig. v.)

The yellow colonies are those from which a small portion was
taken on the end of a sterilized needle and planted in the tube
shown after a few days growth in Fig. I.

The tube and plate in Figs I. and II. are represented of about one
third the natural size.

Fig. III. — Several different forms of bacteria represented as they
look when stained with one of the anilin dyes and magnified about
i, CKDO times (see pages 15, 39, and 40).

Nos. i and 2 : Micrococci, single and in pairs. No. 3 : Micro-
cocci in chains, called streptococci. No. 4 : Tetrads of micrococci.
Nos. 5, 6, 7, and 8 : bacilli, showing different sizes and groupings —
in No. 5, cilia are seen at the ends of some of the bacilli (page 16).
Nos. 9 and 10 : spiral bacteria ; those in No. 9 with cilia. Nos.
II and 12 : bacilli with spores (page 19).

FIG. IV. — A cell in which are seen seven long slender bacilli —
magnified about 3,000 times.

FIG. V. — A single colony as seen under a low power of the
microscope on the plate culture, Fig. II. This is magnified about
20 times.

THE

STORY OF THE BACTERIA

AND THEIR

RELATIONS TO HEALTH AND DISEASE

BY

T. MITCHELL PRUDDEN, M.D.

or THI
{ UNIVERSITY J

NEW YORK & LONDON

G. P. PUTNAM'S SONS

BIOLOGY

LIBRARY

6

/

COPYRIGHT BY

T. MITCHELL PRUDDEN

tEbc

PREFACE.

THE Bacteria are so often nowadays the
subject of discussion and discourse ; so much
which is at once disquieting and untrue is said
about them, and they are withal of such prac-
tical importance to the health and well-being
of everybody, that it has seemed to the writer
worth while to bring together in some simple
fashion a little of our knowledge about them.

The aim then of this book is to present
some facts from a small corner of the domain
of Science in such form as will be plain to the
unscientific, and with these some extracts from
the lore of the physician which will, it is
hoped, be both interesting and useful to the
lay reader.

T. M. P.

iii

144339

CONTENTS

CHAPTER PAGB

I. — THE CELLS WHICH COMPOSE THE HUMAN BODY —

WHAT THEY ARE, AND WHAT THEY Do . . i

II. — WHAT THE BACTERIA ARE, AND SOME OF THE THINGS

WHICH THEY Do . . . . . . .14

III. — How THE BACTERIA ARE STUDIED . . . .25

IV. — SOME BACTERIAL CURIOSITIES . . . . .41

V. — THE BACTERIA AS MAN'S INVISIBLE FOES . , .52
VI. — THE BACTERIA OF SURGICAL DISEASES - . . .59
VII. — THE BACTERIA WHICH CAUSE CONSUMPTION, OR

TUBERCULOSIS . . . .... . .70

VIII. — BACTERIA AND TYPHOID FEVER 84

IX. — THE RELATIONS OF BACTERIA TO ASIATIC CHOLERA . 90
X. — THE RELATION OF BACTERIA TO DIPHTHERIA, PNEU-
MONIA, SCARLET-FEVER, ETC. . . . . .96

XI. — IMPURE FOOD AND AIR AS SOURCES OF BACTERIAL

INFECTION ,..'.' . . . . . . 103

XII. — IMPURE WATER AND ICE AS A SOURCE OF BACTERIAL

DISEASE 116

XIII. — THE END OF THE STORY OF THE BACTERIA . . 134
INDEX I3g

or

VNIVER8ITY

THE STORY OF THE BACTERIA.

CHAPTER I.

THE CELLS WHICH COMPOSE THE HUMAN BODY
WHAT THEY ARE, AND WHAT THEY DO.

T3EFORE beginning to study those low-
U liest and smallest forms of life, the
bacteria, I wish to ask my reader to look with
me in this chapter at some of the higher and
more complex forms of living things. In do-
ing this we shall be following the course which
scientific research has taken, and from the
vantage-ground which we shall gain we shall
be able the more easily to spell out the simple
but significant story of the bacteria, which it is
the purpose of this little book to tell.

In general anatomy we learn that the body
consists of a bony framework, around which

THE STORY OF THE BACTERIA.

various tissues and organs are securely and
compactly grouped. When we have learned
the size, shape, number, relations, and names
of all these parts, our study of macroscopic or
general anatomy is done. If, however, enter-
ing that department of anatomy known as
histology, or minute anatomy, we trace the
manner in which these parts are made beyond
the point where the naked eye can avail us,
we find that they are all composed of certain
tiny organisms called cells, and that these
cells are held together and associated by cer-
tain materials which lie between them.

Just as the chemist has his atoms and
molecules, to which in the last analysis he
refers the properties which all known sub-
stances possess, and explains by differences in
their nature and movements the various chemi-
cal phenomena which matter exhibits, so we
may refer both the structural features and all
the activities of the animal body back to the
structure and activities of our elements — the
cells. While the chemist, however, must infer
the existence of his atoms from their deeds,
armed with the microscope we can see our

THE STORY OF THE BACTERIA. 3

cells, observe the things they do, and definitely
trace out their life-history.

Cells are little masses of matter of peculiar
chemical constitution, and of varied shape and
consistence, which at some time exhibit that
complex of phenomena which we call life : and
the life of one of the higher animals is simply
the sum of the more or less independent but
co-ordinated lives of the cells which compose
it, all acting in harmony.

Living things differ from the non-living in
that they have certain activities through which
their life is expressed. In the first place, they
are capable, in spite of various opposing forces,
of maintaining their individuality, and by
holding a balance between waste on the one
hand and assimilation on the other, a series of
capacities arise which we call nutrition, growth,
and development. Living things, in the sec-
ond place, possess certain activities by means
of which they are capable of producing new
individuals like themselves — in other words,
they are endowed with the power of reproduc-
tion. Lastly, living bodies, in response to
varied influences, are capable of doing certain

THE STORY OF THE BACTERIA.

things in the way of movements or of elabora-
tion of peculiar chemical products, etc., and
these are called their functions.

It will be observed that in enumerating
these activities I have spoken of them not as
characteristic of man, or of any special animal
or plant, but of living things in general. All
life finds expression in these ways. The means
by which the living being does these things
may be in one case exceedingly primitive, and
in another very complicated, but this does not
alter the essential character of the ends which
it achieves.

If you tie a bit of muslin over a water faucet
and allow the water to trickle slowly through
it for a few hours, you will find on removing
it that a more or less abundant greenish scum
has collected on the cloth. Wash this care-
fully into an open dish, and let it remain for a
few days in a light warm place, and then
examine the sediment under a microscope,
and you will find a very celebrated creature.
It is called an amoeba. It looks like a little
lump of transparent or slightly granular jelly.
You will see it thrusting out portions of itself

THE STORY OF THE BACTERIA. 5

in the form of longer or shorter arms, and
then withdrawing them and sending out
others in another place, apparently in the
most aimless way ; or you may see it rolling
itself over and over, or, if I may so say, flow-
ing along so that it travels with considerable
speed. Perhaps some microscopic vegetable
may lie in its way, and it will flow over and
enclose this, and, after digesting portions of it,
expel the residue from whichever side or sur-
face of its body may be most convenient. If,
in a quiescent condition, it be touched by an
external object, you may see it move in direct
response to the irritation. If you are fortu-
nate in your observation, you may see a con-
striction appear around some part of the lump,
which grows gradually deeper until a portion
of the mass separates from the rest and crawls
off on its own hook as a new and independent
amoeba. It has no lungs and yet it breathes ;
no mouth, still eats ; no definite shape, yet
grows ; no nerves, yet is sensitive ; no sex,
yet may give birth to endless progeny.

Now this amoeba is one of the lowest and
simplest of creatures, and is the type of a

0 THE STORY OF THE BACTERIA.

cell — a creature which is composed of a single
cell — and all the activities which I have men-
tioned as characteristic of living things are
exhibited in it. It is a perfectly independent
being, doing every thing for itself, and doing
nothing particularly well, except, perhaps,
performing the function of reproduction,
which it does with such ease and nonchalance
as leaves little to be desired. The young
which it produces are just like the parent,
single cells, and their very first post-natal act
may be to give birth to other amcebas.

Now let us advance a step in the scale of
being, to an animal composed of several cells.
There is a little creature, one of the group of
sponges, called olynthus. Let us start with
the ovum of the animal, which is a single cell,
not very unlike the amceba in appearance.
Under suitable conditions, this cell divides as
the amoeba does, and two cells are produced,
just exactly alike. They do not separate,
however, as do the amcebas, to become inde-
pendent individuals, but remain fastened
together ; then each cell divides again, and
these still further, until we have a little mass

THE STORY OF THE BACTERIA. J

of cells all looking alike, and the whole some-
what resembling a mulberry in shape. But
now a change comes ; the cells on the outside
become longer than the rest, and little hair-
like processes, called cilia, grow out from them
and begin to vibrate to and fro, and, acting
like tiny oars, propel the little creature through
the sea. Presently the rest of the cells arrange
themselves so as to form a central cavity, with
an opening at one side, the whole looking like
a tiny cup. The animal now attaches itself to
a sea-weed or a rock, and no longer needing
the locomotive cilia, they disappear ; but as it
can no longer travel, it can no longer seek its
food, which must be brought to it. Accordingly,
we presently find that through the sides of its
body little holes appear, and the cells lining
the central cavity lengthen and develop cilia,
whose vibrations maintain a current of water
through the body, which brings with it oxygen
and food. This is the adult olynthus.

Now observe, if you please, what has hap-
pened in the development of this little creature.
A single cell divided into several cells, at first
all just alike, and all doing the same thing.

8 THE STORY OF THE BACTERIA.

But soon, as if in response to the growing
needs of the animal, certain of the cells devel-
oped a special apparatus, and a special capacity
for performing rapid movements, and this ca-
pacity was associated with changes in the form
of the cells, — a specialization which signalized
its advance to a higher type of existence.

Just here we come upon the great principle,
in a very simple form, upon which the enor-
mous differences between higher and lower
animals rest, — the principle of the physiological
division of labor in cells. The more perfect
the individual is, the more elaborate do we
find the expression of this principle.

The difference between the amceba and the
olynthus from our present point of view — that
which makes of the latter a higher animal than
the former — is that it has a certain group of
cells set apart to do a special thing, to move
rapidly ; Amceba moves, but not so rapidly
nor with such directness. If another group of
cells were set apart in olynthus to do the
digesting, no new cell powers would be devel-
oped which the amceba does not possess, the
primitive assimilating power would simply be

{ UNIVERSITY j

THE STORY OF THE 9i&Q&&W\**S 9

specialized and intensified, and the animal
would have risen to a higher grade of being.

It would not be difficult, did time permit, to
trace the manner in which, as we pass upward
in the animal series, certain groups of cells be-
come more and more elaborate in structure as
they assume higher and more specialized ca-
pacities. We cannot tarry for this, but will
glance for a moment at the exhibition of this
principle in the development of man. In man,
too, life commences in a single cell called the
ovum ; a cell which, though harboring poten-
tialities of the highest order, in many respects
greatly resembles our little denizens of the
water. This cell, under suitable conditions,
divides and subdivides, forming a little cluster
of cells all looking alike. Then these cells
arrange themselves in layers ; some of them
assume special forms as they increase in num-
ber, and develop special capacities, and group
themselves to form the various tissues and
organs of the mature body, which finally is
formed of a grand community of co-ordinated
groups of cells, some of which have acquired
the power to do special things in the most

10 THE STORY OF THE BACTERIA.

perfect way, while others have remained in a
condition of comparatively low organization.

Let us look at two examples of these two
types of cells from the adult body — first at
certain muscle cells. These in the very young
animal look just like many other cells ; they
are individuals, they are alive and their life
finds expression, just as the amoeba's does, in
certain activities — nutrition, growth, function,
and reproduction. Presently they become
longer than their neighbors, little striations
appear along their sides, they grow long and
narrow until at last they are little thread-like
bodies with a very complicated internal struct-
ure, anJ are grouped in bundles to form the
muscles as we see them with the naked eye.
The peculiarities of structure of these muscle
fibres are necessary for the performance of the
work which they have specially to do — namely,
the accomplishment of rapid and powerful
movements. Now the capacity of the muscle
cells for doing this work has been acquired, if
I may say so, at the expense of some of the
other capacities which they originally possessed
in common with other cells. Thus the power

THE STORY OF THE BACTERIA. II

of reproduction is in them almost if not quite
completely absent. They can also no longer
seek out and take up crude food, but it has to
be prepared for and brought to them, and in
order that this may be done certain other cells
in the body develop the power of elaborat-
ing a peculiar fluid — gastric juice, which helps
to change the crude food so that it finally
becomes fitted for the nourishment, among
others, of the special workers, the muscle
cells ; other cells — the red blood cells — de-
velop the capacity of bringing them oxygen,
and in doing so have lost many capacities
which are possessed by lower forms. Other
cells develop in a peculiar way to form the
nerves by which all the various parts of the
body are brought into harmonious action, and
so on Thus we see in the higher animals
each highly developed cell working for the
others as well as for itself and for the organ-
ism as a whole, only its chief endeavor is con-
centrated in some one special thing, and as a
result of this concentration some of the more
general cell powers are lost or diminished.
Did time permit, I should like to picture for

12 THE STORY OF THE BACTERIA.

you the character and destiny of some of the
lower forms of cells, which we find in the hu-
man body, — those which have not undergone
that differentiation in structure and function
which belongs to higher types ; to speak of
the marvellous potentialities which are dor-
mant in them ; to show you how their very
simplicity of existence, the absence of special
powers, and their boundless capacity for re-
production particularly fit them to become the
conservators of the individual ; to indicate
what an important role some of them play
in the healing of wounds and in the formation

o

of new tissues. So we are not to think of the
lower forms of cells in the body as insignifi-
cant, because under ordinary circumstances
their being and performances are humble
and inconspicuous, for they seem to be ever
ready, either resting quietly in their tiny nooks
within the solid tissues, or driven restlessly in
the rushing torrent of the blood, to assume
again the lowly but active powers of embry-
onic cells, and begin when necessary the work
of reproduction and repair.

These cells have, too, a most important role.

THE STORY OF THE BACTERIA. 13

as we shall see by and by, in combating the
incursion of certain forms of bacteria which
now and then obtrude themselves into this
happy family of cells which makes up the
human body.

We have thus seen that all the varied struct-
ures and functions of the human body are but
the combined expression of the structure and
lives of the cells which compose it, all co-ordi-
nated and working in harmony by means of
self-built, cellular mechanism ; that, starting
with the type of the most simple of living
things, a single cell, the finished organism is
an aggregate of the progeny of the original
cell, some groups of which have developed
special forms and powers, in accordance with
a universal principle in nature ; that the doc-
trine of evolution, even should the record of
the rocks be incomplete and perfect continuity
in the grouping of living species fail, still finds
epitomized in every animal and plant which
has escaped from the primitive simplicity of
the lowest forms, a most pertinent illustration
and convincing proof.

CHAPTER II.

WHAT THE BACTERIA ARE, AND SOME OF THE
THINGS WHICH THEY DO.

" I "HERE are many very good reasons for
A believing that when life first appeared
upon the earth it showed itself in a very sim-
ple and primitive form, in some such form
perhaps as we have seen in the amoeba or
other simple cells. But as the ages passed, in
accordance with the principles of the physio-
logical division of labor, which we have glanced
at in the last chapter, many of the living
beings gradually assumed more and more
complex forms and capacities.

Not all living things, however, shared in
these evolutionary changes. There is, in fact,
a great group of lowly plants, so small as to
be quite invisible to the naked eye, and which
until within a few years have been entirely
unknown to man, which still linger in the

14

THE STORY OF THE BACTERIA. 15

primitive simplicity which we imagine to have
belonged to the earth's earliest denizens.
These are the bacteria.

So small are the bacteria, and so simple in
their structure and activities, that it has not
been an easy task for scientific men to decide
whether they belonged among animals or
plants. It is now definitely settled, however,
that they are plants, and are closely related
to the algae.

The bacteria vary a good deal in shape, but
in general they are either spheroidal or ovoidal,
like a billiard-ball or an egg ; or rod-shaped,
like a lead-pencil ; or spiral-shaped, like a cork-
screw.

They are in general so very small that we
can hardly form a conception of them except
by comparison with some well known objects.
One of the most common of the bacteria is a
little rod, so small that if you were to put fif-
teen hundred of them end to end, the line
would scarcely reach across the head of an
ordinary pin. If you look at them with a
magnifying power so great that, if it could be
applied to him, it would make a man look

1 6 THE STORY OF THE BACTERIA.

about four times as big as Mount Washington,
they do not look larger than this. We can
make out, however that they are made up of a
slightly granular material surrounded by a
somewhat denser envelope.

The bacteria appear under the microscope
as pale translucent bodies, and the student
usually finds it necessary, in order to see their
outlines distinctly, to stain them with some
one of the aniline dyes — red, or blue, or violet,
—when they become very distinct.

When they are alive and suspended in fluids
many of the rod-like and spiral bacteria can
perform the most elaborate and astonishing
series of movements. They swim slowly, they
turn about, they roll over, they wriggle, dart
forward, retreat, bang against one another,
rest awhile, sway to and fro, plunge off again,
and so on through varying phases of move-
ment until the head swims and the eye tires in
following them. This movement, in some of
the bacteria at least, is induced by a little hair-
like projection from the end of the organism,
which vibrates rapidly to and fro. It is very
difficult to see these little projections or cilia,

THE STORY OF THE BACTERIA. I/

even with the most powerful microscopes, but
notwithstanding this, they have actually been
photographed, and in some cases the image
of the cilia, which failed to make an impres-
sion on the retina, has been caught and made
permanent by the sensitive plate in the camera.

Warmth, moisture, oxygen, and a certain
amount of organic matter are the simple con-
ditions which are required for their activities.

When the conditions are favorable they may
increase in number to a degree which is limited
only by their surroundings. A little constric-
tion appears around one of the bacteria ; it
grows a little longer, a partition forms across
the middle, and in the place of one there are
two full-fledged bacteria. These may at once
fall apart and each new individual go on di-
viding as before, or they may cling together,
forming threads or chains of varying length,
or clumps or masses.

So rapid is this process of reproduction that
a single germ by this process of growth and
subdivision may give rise to more than sixteen
and a half millions of similar organisms within
twenty-four hours. It has been calculated by

1 8 THE STORY OF THE BACTERIA.

an eminent biologist that, if the proper condi-
tions could be maintained, a little rod-like
bacterium, which would measure only about a
thousandth of an inch in length, multiplying
in this way, would in less than five days make
a mass which would completely fill as much
space as is occupied by all the oceans on the
earth's surface, supposing them to have an
average depth of one mile.

Let not the timid soul tremble, however, for
the principles of the survival of the fittest and
the influences of environment have kept our
prolific organisms so well in check that the
world had grown very old and its favored
nursling, man, pretty well along in experience
and skill before ever he recognized the exist-
ence of these his microscopic contemporaries
and possible ancestors.

The struggle for existence goes on where
varying forms of bacteria are growing' as fierce-
ly as ever it did among more highly organized
beings. One race succeeds another, one spe-
cies adapts itself to the conditions which
brought about the extinction of its predeces-
sors. Hardy individuals struggle with their

THE STORY OF THE BACTERIA.

weaker neighbors as the food grows scanty in
their microscopic seas, and the weaker goes to
the wall.

Many forms possess the power of living and
multiplying in the manner described above so
long as the proper conditions prevail, but when
life, owing to some change in the environment
becomes no longer possible, the vital powers
collect themselves in a little shining mass in
one end of the bacterium, which surrounds
itself by a dense membrane, and in this form,
which is called a spore, the individual can sur-
vive adverse conditions which in the ordinary
form would have destroyed its life. Restore
it to the needed conditions and the spore
swells into a bacterium again, and the roots of
a new ancestral tree begin to sprout.

These bacteria are really very simple forms
of cells, and like the cells which we have looked
at in the last chapter, their life expresses itself
in certain activities ; they move, they nourish
themselves and grow, they reproduce their
kind. They have the power in carrying on
the processes of their own nutrition, when
moisture and air are present, of tearing to

20 THE STORY OF THE BACTERIA.

pieces, in the chemical sense, dead organic
material, using up such parts of it as they need
for their own purposes, and setting free the
rest in such form as to be available for the use
of other living things.

Everybody knows who thinks about it, that
the supply of such material as makes up the
bulk of the tissues of man, animals, and plants,
on this earth, is limited. So that if things were
not so arranged that living beings should have
the use of the material which goes to make up
their bodies for only a comparatively short
time, the supply would run short and new be-
ings could not continue to appear.

When that mysterious group of activities
which we call life ceases to be manifested, in
animals and plants alike, if moisture and oxy-
gen and sufficient warmth are present, that
process which we know as putrefaction or de-
cay begins, by which the old combinations of
matter are broken up and the material set free
for the use of other beings. Now just here
enter the bacteria. It is they who tear these
old organic compounds asunder, use a little of
them as may suit their own needs, and turn

THE STORY OF THE BACTERIA. 21

over the rest to their earth neighbors, who
have got higher up the scale of being, but not
yet so far as not to need absolutely and hourly
oxygen, hydrogen, nitrogen, and carbon, to
keep their life's furnaces a-going.

Milk is a most excellent food for many forms
of bacteria, and among those which are com-
monly present in milk is one which causes it to
become sour when left to itself. Other forms
of bacteria develop those peculiar chemical
compounds which give to cheese its special
and varying flavors. It is, in fact, a very motley
group of chemical substances which these bac-
teria set free in feeding themselves on nature's
waste organic materials. Sometimes they are
very bad smelling gases, sometimes aromatic
substances, sometimes they are sweet, some-
times they are sour. But sooner or later they
are used by some animal or plant, and so again
enter the domain of life. Thus ever in cease-
less alternations between life and death these
elemental combinations come and go. And
ever since life emerged from its primal simple
forms on the earth, the bacteria have silently
gone on tearing the worn-out and useless to

22 THE STORY OF THE BACTERIA.

pieces and turning it over in new combination
to other forms of life.

It was formerly believed that such lowly
organisms as the bacteria could spring at once
into being wherever in nature the conditions
were favorable, but this notion of spontaneous
generation has long since been given up, be-
cause it was shown to have depended upon in-
sufficient and crude observation. We now be-
lieve that every living thing comes from some
pre-existing living thing, be it man, beast,
plant, or cell, and this principle holds true as
well among the bacteria as among more highly
organized beings.

There is an enormous number of different
species of bacteria, each one of which appears
to preserve its individual characters under all
the varying conditions and vicissitudes to which
it is subject. They are to be found every-
where in nature. Where putrefaction and de-
cay are going on they are most abundant, but
where any form of life can exist they are pres-
ent, either dry and inactive, or where moisture
and food are present, growing and multiplying
in such degree as their surroundings will per-

THE STORY OF THE BACTERIA. 23

mit. In all natural surface waters, in the soil,
on all fruits, vegetables, and plants, in the
mouths and digestive canals of men and ani-
mals, on the skin, wherever dust can go or
collect, there are bacteria of various forms in
greater or smaller numbers.

So common and abundant are the bacteria
that we are constantly taking enormous num-
bers of them into the system with all of our
uncooked food. We should not, however,
think of these little organisms which we thus
unwittingly consume as things necessarily un-
clean or unwholesome, for they are only little
cells after all, and nearly all the food which we
consume, whether animal or vegetable, is made
up of masses of cells which are either fit to eat
in their natural condition, as in the pulp of
fruits, or become so by simple cooking or other
manipulation.

There is really very little difference so far as
wholesomeness is concerned between, the few
thousand vegetable cells which we call bacte-
ria which may be clinging to the surface of a
grape, and a few hundred vegetable cells of
larger size of which the grape itself is com-

24 THE STORY OF THE BACTERIA.

posed. Both are alike worked over by the
digestive organs, under ordinary conditions,
into nutritive material for the uses of the
body.

There are poisonous vegetables, and there
are, more 's the pity, as we shall see by and
by, poisonous bacteria, but we do not shudder
as we swallow a mushroom to think what
might have happened to us if we had swal-
lowed a poisonous toadstool instead ; we sim-
ply trust to the gardener, or if he is dishonest
or ignorant, see to it ourselves that the poison-
ous are not liable to get in with the other
plants, and then go on enjoying our delicacies
like sensible people.

It will thus be seen that the role of the
bacteria in nature, though humble and silent,
is an exceedingly important one. They are
indispensable to the continuance of the higher
forms of life upon the earth. They may well
be called man's invisible friends.

CHAPTER III.

HOW THE BACTERIA ARE STUDIED.

IF you take a small whisp of hay, put it in
an open jar, and covering it with water,
set it in a warm place for a day or two, you
will presently see that the water which was at
first perfectly clear, begins to get turbid, and,
after a while, a grayish scum collects on the
top. Now the water begins to give off a dis-
agreeable odor of decay. This is what has
happened. The bacteria of various forms
which, in the dried condition were clinging to
the hay, or which were in the water, have mul-
tiplied to such an extent that they made the
water turbid, and many of the mobile forms
have sought the surface, where the oxygen
was most abundant. The solution of organic
material from the hay has furnished an
abundance of food, and as the bacteria
have torn this into simpler forms to get the

25

26 THE STORY OF THE BACTERIA.

particular elements which they needed for
their own use, the freed material, in part in
the form of bad-smelling gases, has either been
set free into the air or remains absorbed in the
water.

If you examine a tiny droplet of the water
from time to time with the microscope, you
will find that it is swarming with various forms
of bacteria, rods, balls, and perhaps spirals,
many of them in active motion. But you will
notice that from day to day the prevailing
forms change. One day the little rods will be
most abundant, the next these may have
largely disappeared, and perhaps the little
balls are the most common forms. Then
perhaps a new set of rods or balls will appear
of a different size from the first. After a
while you will find that the bottom of the jar
has become covered with a light-colored sedi-
ment, and the water has become clearer.

The bacteria of one form or another have
gone on dividing and subdividing, breaking up
the dissolved organic matter in the water until
either they had used up the special form of
material which was best suited to their needs,

THE STORY OF THE BACTERIA.

or until the material which they had set free
had so far accumulated as to prevent their fur-
ther growth, and then they died, self-poisoned,
just as a man might who should be shut up in
a tight room until the accumulation of the
products of his respiration and excretion had
made further life impossible. Or they may
die because other species of bacteria growing
in the same fluid furnish material which poi-
sons their neighbors. So the procession of
life goes on, until the bottom of the jar be-
comes a veritable graveyard of races.

Some forms of the bacteria, however, which
seem dead, and fall with the rest to the bot-
tom of the jar, are really only in a resting
stage ; they have formed spores within them-
selves in the manner described above, and may
lie dormant until the proper conditions come
again, when they may spring into renewed
activities. But new species may from time to
time fall into the jar from the air and find in
the water, which was rank poison for the dead
species at the bottom, just the food they need,
and so will the drama of life and death be
enacted anew for long periods.

28 THE STORY OF THE BACTERIA.

In such a confusing mixture as this the stu-
dent finds it no easy task to make out much
except differences in form and movement,
in the jumble of tiny plants. What he needs
to do is to get each species by itself, so that
he can cultivate it alone, and find out what it
is and does under more simple conditions.

The device which was formerly in vogue,
and which was called the fractional method of
separation, was to make some beef-tea — which
is pretty good food for most bacteria, — and
putting a little of this in a great many separate
little tubes, carefully heat them so as to kill all
the bacteria which might by chance have been
in the flasks or in the materials from which the
beef-tea was made. The investigator also
takes a large flask of water and kills by heat-
ing all the bacteria which it may contain. Now
he dips the end of a fine needle, which has
just been heated red-hot to kill the omnipres-
ent germs, into the putrefying mixture. He
rinses off the invisible amount of material
which clung to the needle into the pure water
in the large flask, and thoroughly shakes it so
that the bacteria which he has put into it may
become equally distributed through it.

THE STORY OF THE BACTERIA. 2Q

He calculates that the bacteria which he has
thus put into the large flask of water will have
been so much diluted and separated that, if he
now dips a needle into this water, or takes out
a small drop, and rinses it off into one of the
tubes of beef-tea, and does this for each one
of the several beef-tea tubes which he has pre-
pared, into some of them he will have intro-
duced, small as they are, only one single indi-
vidual bacterium.

He now sets his beef-tea tubes away in a
warm place where no accidental contamination
can occur, and lets them stand until the fluid
begins to get turbid. Now, by a careful mi-
croscopical examination he can tell whether
one or several forms of bacteria are growing
in his tubes, and if in any of them only one
form is present he has succeeded, and has what
he calls a culture of some particular bacterial
species. This he can study at his leisure, plant
and replant it in fresh beef-tea tubes, and find
out to a certain extent what its habits are, what
new chemical substances it produces as it feeds
itself from the beef-tea, etc.

But this is a long and wearisome process
and somewhat uncertain^ in its results too,

3O THE STORY OF THE BACTERIA.

because one can never be quite certain from a
microscopical examination of small portions of
a beef-tea culture, but that in some other part,
for he cannot examine it all, other forms of
bacteria may be present.

Nowadays, although we find beef-tea very
useful on many occasions in cultivating the
bacteria, we most frequently make use of solid
foods.

Boiled potatoes, which have been carefully
cleansed and sterilized — that is, free from any
bacteria from the soil or air — by steaming, are
usually first prepared. These are cut in halves,
with knives sterilized by heat, being held in
the fingers which have been freed from living
germs by washing with corrosive sublimate,
and placed under sterilized bell-jars or in tubes,
so that they may not be contaminated by the
accidental falling upon them of bacteria from
the air. Now, by means of a platinum wire
set in a glass handle, which has been sterilized
by heating to redness, a tiny bit of the bacteria-
containing material is conveyed to the cut
surface of the potato, and the latter is covered
again and set away for a day or two in a warm

THE STORY OF THE BACTERIA. 31

place. Usually at the end of this time, if all
goes well, there will be a growth of the bac-
teria on the potato so large as to be quite
visible to the naked eye. This growth, or
"colony," as it is called, which is made up of
myriads of individual bacteria, the offspring
of those planted, in many cases presents very
characteristic ways of growing or special
colors, etc., characters often by which particu-
lar species of bacteria may be distinguished
from all others, even without the aid of the
microscope. This gross appearance of the
growing colonies is useful in the recognition
of species which under the microscope look
very much alike. Just as in agriculture, if
one were in doubt as to two specimens of seed
which closely resembled one another — say tur-
nip and rape, for example — by sowing them in
the ground and observing the resulting plants,
all doubt would be removed.

In thus planting the invisible and minute
bacteria, and allowing them to grow until such
large masses of colonies are formed that we
can readily see and study them with the naked
eye, we are realizing in another field a project

32 THE STORY OF THE BACTERIA.

which was urged with a good deal of persist-
ency some years ago for finding out if there
were inhabitants in the moon, and for com-
municating with them.

It was proposed to build in outline on some
great plain on the earth's surface, like that of
Siberia, a gigantic structure so large that even
assuming that the lunar inhabitants had no
telescopes, it would be visible to them. This
structure was to have some simple suggestive
mathematical form like a circle or triangle.
Seeing such a thing appear on the earth's sur-
face, it was thought that the lunar inhabitants
would probably " catch on " —this phrase was
not known in those primitive times — and erect
a similar structure, and thus communication
would be established. The moon project fell
through, but as we have seen by a somewhat
similar device, we actually make the inhabit-
ants of an unseen world communicate to us
to-day some of the secrets of their hidden life.

But the knowledge derived from the mode
of growth of bacteria on potatoes is limited,
because as the potato is opaque we can see
only the surface of the colony ; and, further-

THE STORY OF THE BACTERIA. 33

more, not all the bacteria grow well on pota-
toes, and some do not grow upon them at all.
So the next step is to make some transparent
solid substance which shall be a suitable soil for
bacterial growth. One of the most common and
useful substances for this end is a 10 per cent,
solution of gelatin which is mixed with beef-
tea, pepton, and a little common salt, and then
made neutral or slightly alkaline by carbonate
of soda. This mixture, carefully heated so as
to destroy all bacteria which might be present
in its ingredients, is filled into ordinary glass
test-tubes which have been sterilized by a high
temperature. These are filled about one third
full of the gelatin mixture, and the opening
is stopped by a plug of cotton batting. Through
a long plug of cotton, bacteria cannot pass ;
the air can enter and leave the tube, but all
bacteria are caught by the fibres of the cotton.
After the gelatin has become cool and solid,
by means of a sterilized platinum wire, some
of the bacteria are introduced into the gelatin,
the cotton plug being removed for an instant
for this purpose. Being transparent, the gela-
tin permits us to see from the sides as well as

34 THE STORY OF THE BACTERIA.

from the surface the exact mode of growth of
the particular form of bacteria introduced into
the tube, and thus we learn a new set of char-
acteristics for the different species.

But if we need to keep our bacteria at a
higher temperature than that of an ordinary
room, say at the temperature of the body, at
which alone some forms will grow, the gelatin
would melt and the bacteria would be scat-
tered through it, and the characteristic mode
of growth of the masses or colonies would be
lost. So, for this purpose we use, instead of
gelatin, Agar-Agar, a material derived from a
sea-weed, which in one per cent, solution forms
a gelatinous solid transparent mass, which
may be heated to above the temperature of
the body without fluidifying. To this are
added, as to the gelatin, beef-tea, pepton, etc.

By the use of these various soils, or "cult-
ure-media," as they are called, we can arrive
at a series of characteristics in the mode of
growth of various bacteria by which, together
with their form when seen under the micro-
scope, we can distinguish them one from the
other, just as the naturalist distinguishes from
each other nearly related animals and plants.

THE STORY OF THE BACTERIA. 35

It is obviously of the greatest importance,
as we have seen above, that we should be able
to separate different species of bacteria from
one another in the living condition, so that we
may have growths or colonies which shall con-
tain one species alone without admixture with
any other. These are called " pure cultures."
This is by no means an easy task, as will be
appreciated when we consider how exceedingly
minute the organisms are, and how much dan-
ger there is that the bacteria floating every-
where invisibly in the air, may become mixed
with those forms which we are studying. By
a very simple device elaborated by Dr. Koch,
of Berlin, we are, nevertheless, able at any
time to separate one species from another with
the utmost certainty, or from a mixture of
many species to get into separate tubes pure
cultures of each species by itself. This is
accomplished by what is called the "plate
culture," the details of which are as follows :
Suppose we have a mixture, say a sample of
impure drinking water, which contains
four different species of bacteria, which we
wish to get into pure cultures in separate
tubes.

36 THE STORY OF THE BACTERIA.

We mix thoroughly a small amount of the
bacteria-containing water with a much larger
amount of the above-described nutrient gela-
tin, rendered just fluid by heat. Then we
pour this mixture out onto a glass plate which
has been carefully sterilized by heat, so as to
form a thin layer, which soon cools and be-
comes solid. The glass plate is now covered
with a bell-jar to prevent the access to it of any
bacteria which may be floating in the air, and
to prevent its drying, and set it away at the
proper temperature. The individual bacteria
which were scattered through the gelatin layer
will presently commence to grow.

After a few hours or days, as the case may
be, if we look at the gelatin-film we see, some-
times with the naked eye, sometimes only un-
der the microscope, little points or masses
scattered through the gelatin, which are colo-
nies of bacteria, each one consisting of hun-
dreds or thousands of the organisms which
have grown from the single organism which
was fixed at that point as by a solid wall when
the gelatin cooled.

Of course, it sometimes happens that two or

THE STORY OF THE BACTERIA. 37

more of the original germs either of the same
or different species were solidified in the gela-
tin when it cooled at the same place, and then
the resulting colony will consist of all the
organisms which have grown at this point,
mixed together or growing closely side by
side. In most cases, however, the little colo-
nies are composed of the descendants of a
single germ, and if we put the gelatin plate
under the microscope we can see the different
forms of the colonies which have grown from
the different species. The differences in the
mode of growth of the bacteria when planted
and studied in this way are manifold ; some
are colored, red, green, yellow, orange, violet,
brown, etc. ; some are colorless, some have
sharply defined smooth edges, some are jagged
or fringed, some are beaded, or send out little
spines ; some cause the gelatin in their imme-
diate vicinity to liquefy, so that they come to
lie in a little pool of fluid in a pit or depression
in the solid gelatin.

Now, by examining the plate microscopically
we cannot only see how many different forms
of colonies there are — and each different form

38 THE STORY OF THE BACTERIA.

of colony indicates a difference in the species
of bacteria composing it, — but nothing is
simpler than, directly under the microscope, to
take out on the tip of a sterilized platinum
wire little bits from each one of the different
forms of colonies, and transfer them to separate
tubes of gelatin. Thus we secure "pure cult-
ures " of all the different forms of bacteria
which were contained in the original mixture.
Thus, minute as the individual bacteria are,
lying far below the power of unaided vision,
we are able to manipulate them with as much
certainty as the agriculturist does his larger
plants.

When we have thus got different species of
bacteria separated from one another in the
form of pure cultures we can experiment on
them in many ways, and learn their varying
characteristics. We can plant them under
such conditions that their oxygen supply is
limited, and learn whether they do or do not
thrive ; we can see whether they grow best at
high or low temperatures, and what degrees
of heat or cold will kill them ; we can grow
them in large quantities, and study the chemi-

THE STORY OF THE BACTERIA. 39

cal compounds which result from their life
processes. We can apply to them various
chemical substances which are called germi-
cides, or disinfectants, and find out to which
of these and in what strength they most readily
succumb.

In this way a large number of different
species of bacteria have been studied, and
these have been arranged in groups which
have some characters in common. So that
already, although the study of the bacteria by
the new methods is of very recent date, we
have the outline of analysis tables, something
like those made for the identification of the
higher plants in Gray's " Botany," for instance,
by the use of which the student can identify
certain of the better known forms which he
may come across in his studies.

The nomenclature in bacteriology is still in
a rather chaotic condition, but a beginning has
been made. The term bacteria (singular, bac-
terium) applies to the whole class of organisms
of whatever shape. They are also sometimes
called " germs." Micrococcus is the generic
name of the most common forms of the spher-

40 THE STORY OF THE BACTERIA

oidal bacteria. Thus there is a species of mi-
crococcus which produces a yellow color when
it is growing in masses. This species is called
Micrococcus luteus. There is another species
of micrococcus which when growing has the
peculiarity of a grouping of the micrococci, or
cocci, as they are sometimes called, in fours ;
this species is called Micrococcus tetragenus.

Another genus among the spheroidal bac-
teria is called Streptococcus, because the little
balls tend to cling together and form longer
and shorter chains as they grow. Then among
the rod-shaped bacteria the most common ge-
nus is called Bacillus (plural, bacilli), and some
of the species of this genus are among the
most common and abundant forms.

Thus with a temporary and provisional sys-
tem of classification, the work of studying
and describing the bacteria is steadily going
on. And if to see and describe living beings
on which no human eye has ever rested before
be satisfying, it will be long before the sighs
of bacteriological Alexanders are heard in this
unseen world, whose very shores have been
barely touched by the new explorers.

CHAPTER IV.

SOME BACTERIAL CURIOSITIES.

MOST travellers, and some people who
stay at home, too, have now and then
been mystified and delighted, when not fright-
ened, to see in the night-time that wavering,
cold, uncanny, but beautiful light, sometimes
tinged with the most exquisite green or blue,
which is commonly called phosphorescence.
Sometimes it is seen in decaying plants or
wood ; sometimes bays or inlets of the sea are
fairly luminous with it. The surface of dead
fish and of meat and various kinds of vegeta-
bles often become so bright as to illuminate
the storage rooms in which they lie.

Some time since there was brought to the
laboratory for examination a cluster of sausages
which had been destined to grace a boarding-
house breakfast-table. To the consternation
of the maid who went into the dark cellar

41

42 THE STORY OF THE BACTERIA.

for them in the early morning, there hung in
the place of the sausages a fiery effigy which
seemed to her more like the quondam spirits
of their mysterious ingredients than the unc-
tuous homely friend of the homeless boarder.
The explanation of this is now simple
enough without recourse to the supernatural ;
for it has been recently shown that this curious
light which various organic substances emit is
due, in many cases at least, to the enormous
numbers of certain kinds of bacteria which are
present on their surfaces, hard at work feeding
on the organic compounds which are present
and undergoing decay. Pure cultures of these
singular bacteria have been made and culti-
vated in considerable quantities. These bac-
terial masses, together with the tubes in which
they were growing, have been placed in a dark
room with an open watch beside them, and
bacterial masses, tubes, and all actually photo-
graphed by their own light, the pointers of the
watch showing distinctly the time of day. So
it would seem that this cousin of the will-o'-the-
wisp — no doubt often mistaken for him — is no
malevolent genius after all, but a quiet little

THE STORY OF THE BACTERIA. 43

citizen working- away as diligently as he can
to make the world more comfortable for his
betters.

It has long been known by the makers of
beverages that alcohol is formed in certain
sugary mixtures by a process called fermenta-
tion, and that this tearing to pieces of the
sugar into other compounds, one of which is
alcohol, is accomplished by a little living or-
ganism called yeast, closely related to the
bacteria. In the earlier days of beer- and wine-
making it was often found that the beer did
not work or ferment properly, and that wine
would get sour or bitter. We now know that
these irregularities are due to the fact that
certain kinds of bacteria are apt to get into
the wine or beer during the manufacture, and
when they do a bitter struggle for food goes
on between the yeasts and the bacteria ; or
the latter may bide their time, and later in the
process begin to grow and produce very unde-
sirable compounds in the fluids. So the man-
ufacturer has to be on the alert, and at the
right moment come to the rescue of his army
of servitors, the yeast plants, and introduce

•
^r r

44 THE STORY OF THE BACTERIA.

into his beer some chemical substance which
is innocuous to them but deadly to the intrud-
ing bacteria. Or he may raise his wine at a
certain period to such a temperature as will
suffice to kill the bacteria but not injure the
flavor of the already fermented juice. Here
for the first time we see the bacteria coming
in conflict with the purposes of their earth-
neighbor — man.

Some of the bacteria are great lovers of
oxygen, and if they are shut up in a little cell
containing a few drops of water in which a bub-
ble of air has been enclosed, after a while it will
be found that those forms which are caoable
of locomotion have made their way from
all parts of the fluid, which is a veritable ocean
to them, and are closely clustered around the
air bubble, jostling and bumping against one
another in the most reckless way. It seems
almost as if this rush towards the oxygen were
an evidence of volition in its simplest form
way down on the lowest border-line of life.

Some forms of bacteria are exceedingly in-
vulnerable to the action of cold, and can not
only move actively about in very cold water,

THE STORY OF THE BACTERIA. 45

but can remain alive for long periods fast
frozen in a mass of ice. Now a very curious
thing has been noticed in the ice which is
gathered in these regions and which we use
for domestic purposes, and that is, that the so-
called bubbly streaks which we usually see in
our ice blocks contain, as a rule, many more
bacteria than does the transparent ice close by.
It has been found, on cultivating the bac-
teria from the bubbly streaks, that the species
which was most abundant here is an oxygen
lover, and is also very mobile. Now the bub-
bles which collect in streaks or layers in the
ice collect during the daytime, or when the ice
is not freezing very fast below, and there is
time for the a$r-seeking bacteria to gather
around them in great numbers. But now,
when a clear night or a cold snap comes on,
the ice closes around both bubbles and bacte-
ria, and we have formed, to use the language
of the geologist, an air and fossil-bearing
stratum. Only our bacterial fossils are not
dead, and all we have to do in order to find
out what forms of life were present in our suc-
cessive geological periods, limited perhaps

46 THE STORY OF THE BACTERIA.

only by a night, is to melt a bit of the ice, mix
it with our culture gelatin, and in a day or two
we shall have a whole garden of growing
plants, which we can study at our leisure.

Among the most curious things which the
bacteriologist has to exhibit in his bacterial
conservatory is the color-forming species. It
is only when they are growing in masses, of
course, that enough color is formed to be visi-
ble ; but then one may see in the little slimy
masses which cover the surface of the food or
culture media in the tubes, every color of the
rainbow and many variations in hue. Some-
times not only is the bacterial mass itself
brilliantly colored, but some of the chemical
substances which they form as they grow
permeate the gelatin and give it a beautiful
fluorescence, green or red.

The writer was not long ago standing be-
side a supper-table, whose sole floral decora-
tion was a bunch of large, exquisitely tinted
chrysanthemums, when a friend remarked upon
the patience and skill which had been required
to develop this magnificent flower by artificial
selection from its simple and homely ancestor,

THE STORY OF THE BACTERIA. 47

and queried in a quizzing way how long it
would be before somebody would be trying to
modify the colors of some of the bacteria by
the well-known horticultural methods. His
idea was a clever one, but he was behind the
times, for already a German bacteriologist
had, starting with a deep purple-forming spe-
cies of bacteria, and selecting and replanting
the lighter-colored colonies, at last obtained
cultures which were nearly white, but were in
other respects essentially the same. Thus the
great and far-reaching principles of natural
selection, in accordance with which life, slowly
emerging from its primeval simplicity, at last
came to be manifested in that grand scale of
living beings at the top of which man stands
supreme, are still to be traced way down among
the invisible organisms which typify the earliest
and simplest expression of life.

But certain of these color-forming bacteria
are sometimes very disagreeable intruders
upon domestic life. Occasionally, without
warning, the milk of a particular dairy sud-
denly develops a very uncanny deep-blue
color, which, like an epidemic, spreads to all

48 THE STORY OF THE BACTERIA.

the milk which is stored in special rooms.
This occurrence, for a long time a disagreeable
and costly mystery, is now known to be due to
a tiny bacterium of the genus Bacillus, which,
floating about in the air with the dust, from
time to time infects rooms, and, falling into
the milk, grows there, producing the blue
coloring matter.

Sometimes milk gets red instead of blue,
and then the change is due to another form of
bacteria floating with the dust. Bread, too,
may become infected in the same way, and the
dough set aside in bake-shops overnight to
rise has not infrequently been found in the
morning resplendent with colors which fairly
rivalled those of the rising sun.

There is a species of bacteria in every good
collection, and a veritable Nestor among the
forms known to man, which has a curious
ecclesiastical history. Among all the innu-
merable natural phenomena which, by their
striking character, infrequent occurrence, and
lack of apparent cause, were in early times
relegated to the domain of the supernatural,
none perhaps was more strange and uncanny

THE STORY OF THE BACTERIA. 49

than the sudden appearance on the moist sur-
faces of articles of food of little bright-red
shiny droplets, which, gradually spreading, at
length formed large shiny, deep, rich-red
masses, looking very like drops, or masses, or
clots of blood. The story is long and tragic
of the dire calamities, unmentionable crimes,
and swift retributions which these strange ap-
pearances of blood were supposed to fore-
shadow.

This miracle of the bleeding Host has
appeared again and again in the hands of the
priestly defenders of the faith as a most potent
evidence of divine intervention with the affairs
of men. The consecrated wafer placed over-
night in the moist and bacteria-laden air of
the church edifice, would in the morning be
found besprinkled with bright-red drops.
What could it be but blood ? No human
hand could have come near the place, and so
what else could be believed but that it was
from the hand of God? It was one of those
early miracles in which both priest and layman
could alike share in believing with perfect
honesty. The divine finger pointed, but to

50 THE STORY OF THE BACTERIA.

what, it was the office of the priest to say.
How many lives were sacrificed and homes
destroyed through that most honest of eccle-
siastical delusions, the miracle of the bleeding
Host, it were useless now even to conjecture.

To-day we cultivate in our tubes the tiny
bacteria which, growing in masses, made the
drops of blood, and the last elements of
romance and tragedy seem to disappear from
the story as we name them — Bacillus prodigi-
osus.

There are some species of bacteria which
are mortal enemies and cannot live together,
one species killing out the other almost as
soon as they come in contact. The details of
this invisible mimic warfare we do not yet
understand, nor do we know what are the
weapons with which it is carried on. It is
probable that it is in virtue of some poison
which they form as they live and grow that the
victors gain possession of the field.

On the other hand, there are two or three
instances of a sort of one-sided Damon-and-
Pythias story among these creatures ; for in
the attempts to isolate the species by culture it

THE STORY OF THE BACTERIA. 5!

has been found that sometimes two species can
be isolated and grow together, but if the at-
tempt be made to separate them, one of them
always dies. The exact nature of this friendly
tie is still unknown. Perhaps in this case the
material which is set free by one species as it
feeds and grows is the only thing which its
associate can live and thrive upon.

CHAPTER V.

THE BACTERIA AS MAN'S INVISIBLE FOES.

WE have seen that the bacteria in general
are not only curious and interesting
as objects of study, but in the work which they
are ceaselessly and silently doing they are ab-
solutely indispensable to the continuance of
the higher forms of life upon the earth. But
unfortunately there is another darker side to
the picture. Among the myriads of useful as
well as harmless bacteria, we have lately
learned that there are a few forms which find
the most favorable conditions for their life and
growth in the bodies of men and some of the
higher animals.

They do not grow well in nature as other
bacteria do, nor do they thrive on ordinary
decomposing organic matter. They look very
much like the more common harmless bacteria,
some being little balls, some rods, and some

52

THE STORY OF THE BACTERIA. 53

spirals. Like other bacteria, they grow at the
expense of the materials with which, under
favorable conditions, they come in contact, and
like them they produce new chemical com-
pounds as the result of their life processes.
When they get into the human body, the dif-
ferent forms grow in different ways, and pro-
duce different kinds of chemical compounds,
and this growth or the poisonous chemical
compounds which are produced cause disease.

Bacteria which can grow in the body and
produce deleterious effects there are called
pathogenic or disease-producing bacteria. The
poisonous chemical compounds which they set
free as they grow, are called ptomaines.

Now, before we try to comprehend how
disease can be produced by bacteria, we ought
to understand what disease is.

We have seen in the first chapter that the
human body is made up of several communi
ties of cells, each community having acquired
the power of doing some special thing for the
good of the body as a whole, and that these
cell communities are all co-ordinated so as to
act in harmony. We have seen that these

54 THE STORY OF THE BACTERIA.

cell communities which make up this wonder-
ful mechanism are all originally derived from
a single living cell, the ovum.

What this mysterious thing is which we call
life, which from the original cell, the ovum, is
imparted to all the myriad specialized cells
which spring from it as the body grows ; what
it is which determines that from one of two
cells which under the most powerful of micro-
scopes look exactly alike there shall develop a
man, and from the other an animal, we simply
do not know. We theorize, we speculate, we
draw analogies, we give names, but at the
end we conclude that we must wait still for
more light. We do know, however, that this
self-built cellular mechanism, the body, which
is alive, has in it the power of self-renewal :
the power, when once started, to go on doing
the various things for which it is fitted for a
certain time, provided that the proper external
conditions are maintained. But sooner or
later the machinery begins to creak and trem-
ble, sometimes in one part, sometimes in
another, sometimes everywhere, and gradually
or suddenly that combination of activities

THE STORY OF THE BACTERIA. 55

which we call life disappears, and the worn-out
mechanism for the first time since it came into
being is still. This is death. There is no
disease, but, as we are apt to say — not because
it means much, but because we think we must
say something, — an exhaustion of the vital
forces. The mechanism is worn out, and so
can no longer develop out of food and air the
self-renewed impelling force. It is death from
old age. But this is comparatively infrequent.
If the proper food, air, and surroundings are
maintained, the various co-ordinated cell com-
munities which we call liver, brain, kidneys,
lungs, integument, and so forth, provided they
are properly set going in the first place, have
not only the power to go on doing their work,
but they have a well marked capacity for over-
coming and resisting deleterious agencies of
one kind and another, — a sort of health inertia.
The muscle cells do make shift to contract
even though their food supply be temporarily
scanty ; the blood cells will carry a certain
amount of oxygen in their ceaseless rounds of
visits to the tissues, though the air from which
they get it through the lungs be as foul and

56 THE STORY OF THE BACTERIA.

meagre as it is in some of our fashionable
theatres and churches and school-rooms. And
if certain cells or groups of cells should be
forced to work awry, they always tend to get
back to their proper work and conditions even
against great obstacles, just as soon as they
can.

Even when large numbers of cells or cell
groups are entirely removed from the commu-
nity, as by an injury, new cells can form out
of those which are left, or the duties of the
lost cells are assumed and may be permanently
maintained by their fellows. Patriotism and
esprit du corps are very markedly typified in
the cell communities of which our bodies are
made up.

When important cell communities are seri-
ously injured or changed in structure so that
they cannot do well the things which they
ought to do, or when they fail to act in har-
mony, through some fault of their own or some
disorder in the co-ordinating mechanism, the
failure in what we may term the rhythm of the
body's activities constitutes what we call disease.

The part which may be the seat of the dis-

THE STORY OF THE BACTERIA. 57

ease is as varied as are the organs and tissues
of which the body is composed.

The disturbances in the activities of the
body which result from these changes in the
structure and action of the various parts have
been so long studied that the educated physi-
cian is usually able to tell from certain irregu-
larities of the body's activities what part or
parts it is which are affected. In many cases
the physician does, in some he does not, know
what the exact cause is of the disturbance. In
some cases, when the cause of the disturbance
is known, he can remove it either by directing
a change in the habits or by the administration
of drugs, and then the tendency of the cell
communities of the body to get back into their
proper condition of themselves alone will
restore health. Sometimes this inherent ten-
dency is aided by the use of medicines. Some
of the body's disturbances tend to pass away
of themselves after a longer or shorter period,
if they are not so severe as to destroy life.
Under these conditions the duty of the physi-
cian may be only to aid the body by food and
stimulants in the work which it is doing itself.

58 THE STORY OF THE BACTERIA.

And so through the long list of ills which come
upon the human frame, from known or un-
known causes the wise physician guides and
aids the natural recuperative tendencies of the
body cells.

Among all the varied changes in structure
and disturbance in activities of the body which
thus constitute disease there are, as we have
seen, several, and these most important ones,
which have recently been proven to be caused
by bacteria. To some of these we must now
turn our attention so as to learn how the dis-
turbances are brought about, and what we
may do for ourselves to avoid them.

CHAPTER VI.

THE BACTERIA OF SURGICAL DISEASES.

ONE of the greatest dangers associated
with injuries and wounds of the body,
whether inflicted by accident or made by the
knife of the surgeon in necessary operations,
is the liability to what is known as blood
poisoning.

So great is this danger, that it has long been
known that in war a great many more lives
are lost from blood poisoning than by bullets
or cannon-balls. The cause of this form of
disease, which is so apt to complicate wounds,
was for a long time entirely unknown. Then,
as these wounds were apt, in blood poisoning,
to be foul and bad-smelling, it was concluded
that the trouble might be that dirt or filth of
some sort got into them and so set up the dis-
ease.

What the particular thing was, whether

59

60 THE STORY OF THE BACTERIA.

bacteria or something else, which so gained
entrance to the body, no one knew. But the
surgeons did not wait until they should know
all about the cause of the trouble, but began
to apply to the wounds such materials as would
actually kill germs, or, at any rate, keep the
wounds free from putrefactive changes. Car-
bolic acid, dissolved in water, was found to be
efficient in this way in washing the wounds.

Then, as it seemed more and more as if the
trouble were due to living germs falling upon
the wounds from the air with the dust, it be-
came the practice, when surgical operations
were being done or wounds dressed, to spray
carbolic in the air about the operator's hands
and over his instruments and upon the wounds,
and when the bandages were put on to seal
them in tightly, so that no germs could gain
access to the wound while the healing went
on. All this time the particular species of
bacteria which produced the trouble remained
entirely unknown ; indeed, it was only an
hypothesis that the disease was due to germs
at all.

A great deal of careful laboratory work has,

THE STORY OF THE BACTERIA. 6 1

however, been done recently on this subject,
and a great many animal experiments made,
until now we know not only that blood poison-
ing but abscesses, erysipelas, and many other
less serious inflammations are caused by bac-
teria. We have found out, furthermore, that
there are two particular species which cause
the trouble in the great majority of cases.

Both of these bacteria are little balls or
micrococci. One of them, as it grows, tends
io form chains, and so is called Streptococcus ;
the other tends to group itself in clusters a
little like a bunch of grapes, and so is called
Staphylococcus.

Now, it has been further found that these
two forms of bacteria are quite abundant
where people are gathered, mostly in dirty
places ; sometimes where the healthy, but espe-
cially where sick people are crowded together,
as in hospitals, They are found in small num-
bers floating with the dust in the air, where
dust lodges, and often in the mouths and on
the clothing of the people themselves.

It is thus evident how the wound diseases,
such as blood poisoning, can come about, for

62 THE STORY OF THE BACTERIA.

wherever the dust falls on the open surfaces of
the. wounds or on any thing which comes in
contact with them, and the living bacteria
lodge, they may, if not destroyed, commence
to grow, and not only by the poisonous mate-
rials which they form as they grow, interfere
with the healing of the wounds, but they may
get into the blood and be carried to various
parts of the body, there growing and produ-
cing sometimes fatal results.

It is one of the greatest practical triumphs
of science in modern times that the surgeon
can now so carefully plan out his operations
and treatment of wounds, that not only is
blood poisoning, as it used to prevail but a
few years ago, the greatest rarity among edu-
cated and skilful surgeons, but the most ex-
tensive operations, such as opening the great
cavities of the body, may now be done, when
they are necessary to save life or make it
endurable, with very little risk of the frightful
dangers which formerly attended such pro-
cedures.

Childbed fever, which in former times
claimed so many victims under especially lam-

THE STORY OF THE BACTERIA. 63

entable circumstances, and which used some-
times to spread with frightful rapidity among
women whose confinement took place in hos-
pitals, is now of comparatively rare occur-
rence, because the educated physician knows
what the particular element of danger is and
how to avoid and combat it. For it has been
found that childbed fever is really a form of
blood poisoning, due to the same germs as
induce the disease in ordinary wounds.

Dr. Oliver Wendell Holmes, early in his
career, became convinced that the poison caus-
ing childbed fever could be carried on the
clothes of the physician from one patient to
another. What the poison was he could not
even fairly conjecture, but of the fact he was
certain. In spite of much opposition and ridi-
cule he urged his views, and many lives were
ultimately saved and epidemics stayed because
of his persistency in making known his facts.
To-day we not only know that all that he
urged was true, but the poison which he as-
sumed but could not see has been proved to
be bacteria, and we can now cultivate them
in tubes and know exactly what will most

64 THE STORY OF THE BACTERIA.

surely destroy them. While literature owes
much to the wit and cleverness of the genius
of the breakfast-table, science and humanity
are not less debtors to the zeal and pertinacity
of the young doctor, who still declared for his
beliefs, though his more aged and then more
renowned confreres applied to him many terms
of opprobrium and disrespect.

Now let us look a little more closely at the
way in which these tiny organisms cause in-
flammation, suppuration, or the formation of
pus and blood poisoning. We have seen in
the first chapter that although most of the
cells of the body have assumed special forms
and powers as the body develops out of its
embryonic stage, there are some cells which
scarcely seem to have got beyond the stage in
which the simplest of the unicellular organ-
isms, such as the amoeba, belong. The most
prominent of these lowly organized cells in
the body are the white blood-cells or, leucocytes
as they are called. Under ordinary conditions
they go circling round the blood-vessels along
with the red blood-cells, or, crawling out of the
blood-vessels, slowly make their way around

THE STORY OF THE BACTERIA. 65

in the smaller spaces in the tissues. Exactly
what they do under these circumstances we do
not know. There is some reason for think-
ing that they act to some extent as scaven-
gers, and when they come across a particle of
worn-out or foreign material in the tissues, take
it into themselves, just as amceba does its food
in water, and either digest it or carry it back
to those parts of the body in which waste ma-
terial is systematically disposed of.

But let an injury such as an open wound
occur, and the whole attitude of these leuco-
cytes changes. They get out of the blood-
vessels with all speed, in greater or less num-
bers as the occasion may demand, and gather
about the edges of the wound, and after a
time they, together with some other cells of
the injured tissue, change their shape and
character, and actually form, with the aid of
the blood-vessels near-by, a mass of new tis-
sues, which replaces that which was lost by
the injury, and so permanently binds the edges
of the wound together. Sometimes these white
blood-cells gather in much greater quantities
about the wound than is necessary, and then

66 THE STORY OF THE BACTERIA.

they are thrown off in the form of a material
which we call pus.

Now to come back to the bacteria which we
are studying. When these bacteria get into the
tissues, they may begin to grow, and as they
do so they produce a small amount of a poison
which we call a ptomaine, and this poison act-
ing injuriously on the tissues where it is
formed, the white blood-cells gather about it
just as they would about a wound. If the
bacteria continue to grow and multiply, the
white blood-cells may accumulate more and
more and die, the tissues may break down,
and so an abscess may be formed. Some-
times the germs get into the blood and are
carried to various parts of the body, and
wherever they lodge abscesses may be formed,
and this constitutes one of the most dreaded
forms of blood poisoning.

Now what do the white blood-cells accom-
plish under these circumstances ? Many be-
lieve, although the matter has not been quite
settled yet, that when these bacteria get into
the tissues and begin to grow, the arrival of the
white blood-cells upon the scene signalizes the

THE STORY OF THE BACTERIA. 67

commencement of a life-ancl-death struggle be-
tween the bacteria and the cells. The cells
attempt either to swallow and thus kill and
digest the bacteria, or to so closely surround
them as to cut off their oxygen and food sup-
ply and so destroy them. The bacteria, on
the other hand, so long as they can grow and
proliferate, produce a poison which may kill
the white blood-cells and break up the other
tissues round about.

There is much reason for believing that this
is what actually occurs : that the resisting ca-
pacity of the body to the incursions of these
invisible organisms is largely resident in these
lowly organized cells, which in carrying on
their simple cellular activities assume the role
of defenders of the body against the bacterial
invaders. If the conditions are favorable for
them the white blood- and other cells may get
the upper hand of the bacteria and stop their
growth or kill them all off and thus avert the
danger. If, on the other hand, the cells are
not vigorous enough to resist the poison elimi-
nated by the bacteria and themselves succumb
to its influence, the way is opened to the spread
of the infecting germs.

68 THE STORY OF THE BACTERIA.

It sometimes happens that so extensive a
growth of the bacteria occurs in some local
region of the body and so much of the soluble
poison is produced that although the bacteria
may not themselves get generally distributed
the poison which they furnish may enter the
circulation, and so produce in distant parts of
the body most serious disturbance or even
cause death. These bacteria apparently do no
harm when they lodge upon the uninjured sur-
face of the body, but only when they get into
the tissues through an injury or lodge upon sur-
faces of the respiratory or digestive tract which
are already the seat of disease.

This is in brief the story of the bacteria
which most commonly produce the common
inflammations of the tissues, the complications
in the healing of wounds, and the varying
phases of blood poisoning. As pus in greater
or less quantity is apt to be produced under
these circumstances, these bacteria are called
the pus-forming or pyogenic bacteria. Some
other bacteria may occasionally produce simi-
lar effects, but those which have been described
are the most common and important.

THE STORY OF THE BACTERIA. 69

The effects which these as well as other dis-
ease-producing bacteria may produce in the
body vary considerably under different condi-
tions. Sometimes the general condition of the
body is such that it seems to furnish very
favorable soil for their proliferation or is espe-
cially vulnerable to their action. Sometimes
the particular germs which gain access seem to
be especially virulent, perhaps from their inhe-
rent vigor or from conditions which we know
nothing about. We are in these diseases deal-
ing with poisons of the human body, but with
self-propagating poisons which from an almost
infinitesimal amount may grow to such quanti-
ties as will fairly overwhelm the body.

CHAPTER VII.

THE BACTERIA WHICH CAUSE CONSUMPTION, OR
TUBERCULOSIS.

MORE than one seventh of all the people
who die are carried off prematurely by
consumption, or tuberculosis. But it is only
within the present decade that we have had
any definite knowledge as to the cause of the
disease. For a great while physicians have
known a great deal about it. They have be-
come very expert in detecting its advent and
in tracing its course, and came long ago to
know but too well whither it tended. The
disease was usually regarded as hopeless, and
its treatment was entered into rather for hu-
manity's sake than in the expectation of in-
ducing a cure. To-day the aspect of affairs
has greatly altered. We know that tubercu-
losis is caused, and caused alone, by exceed-
ingly minute, rod-shaped bacteria, which, in

79

THE STORY OF THE BACTERIA.

one way or another, gain access to the body.
When there, if the conditions are favorable,
they tend to grow, and as they do so there
form about them little masses of new tissue,
which are called tubercles. The most common
seat of the disease is the lungs, but it may oc-
cur in any part of the body.

It is not necessary for our purposes to enter
further into the details of the progress of the
disease. It is but too well known to nearly
every one who has seen one and another pass
away from sight under its insidious progress.
It is our purpose here only to show how the
disease is commonly acquired.

Not all persons are equally liable to be at-
tacked by tuberculosis. There seems to be a
certain condition of the body cells which pre-
disposes to the disease, and this predisposition
is in the most marked degree hereditary. We
do not know yet in what this predisposition
consists. We believe that when the tubercle
bacillus gets into the healthy body the cells of
the part in which it lodges in some way tend
to resist its growth, or afford unfavorable con-
ditions for its development. The temporary

72 THE STORY OF THE BACTERIA.

hypothesis around which we try to crystallize
our accumulating knowledge is that in heredi-
tary predisposition to tuberculosis this in-
herent resisting capacity of the cells to the
incursions of the germs is in some way dimin-
ished. This is very indefinite, it is true, but
it is the best we can do at present. We know
that tuberculosis is never caused by any other
thing than the tubercle bacillus, and that even
in persons predisposed by inheritance or other-
wise to the disease it cannot occur unless this
particular germ gets into the body from out-
side. The germ itself has rarely, if ever, been
shown to be directly inherited. If, therefore,
we could keep this particular germ away from
human beings, there would be no more tuber-
culosis, no matter what the inherent tendencies
of the individual might be.

Let us now see what our knowledge teaches
us as to the sources of infection with the
tubercle bacillus. In the first place, we should
not forget that as the early stages of the dis-
ease are often very insidious in their progress,
and as an individual may actually have a
moderate degree of tubercular disease for a

THE STORY OF THE BACTERIA. 73

long time without the slightest disturbance of
the general health, and, furthermore, as the
germs in greater or less number are widely
distributed in densely inhabited regions, it is
usually quite impossible to say in any particular
case what the source of the infection was.

Cattle, in this as in many other countries,
are very frequently the victims of tuberculosis,
which is caused by the same germ as is the
disease in man. As the living tubercle bacilli
may be contained in the milk from diseased
cows, and in the flesh of affected cattle, it
appears that here is an important source of
danger.

It is almost inconceivable that any man not
wholly given over to the spirit of the Devil
should be capable of sending into the market
meat from tubercular cattle, if he is aware of
it. Yet there is reason for believing that a
very considerable amount of such diseased
meat is actually sent into our large towns
every year, with the full knowledge of some
of the unscrupulous dealers, and probably
consumed, usually by the poorer and more
ignorant classes. Thorough cooking of such

74 THE STORY OF THE BACTERIA.

diseased meat would kill the bacilli, but a large
amount of meat is everywhere commonly con-
sumed uncooked, or but partially cooked, in
the form of sausages or other minced messes.

Infection with the tubercle bacillus in the
intestinal canal is not so liable to occur as in
some other parts of the body, even among
persons predisposed to the disease. But,
nevertheless, the danger from tubercular milk
and meat is a very real and a growing one.

The most frequent seat of affection with the
tubercle bacillus is the lungs, and the most
common way in which the germs gain access
to the respiratory passages is by being
breathed in with the dust which is floating in
the air in rooms or regions where tubercular
persons have been. In other words, tubercu-
losis is most commonly acquired by indirect
transmission of the tubercle bacilli from man
to man through the dust of the air.

Now the most common way in which the
tubercle bacilli get into the air from consump-
tive people is this : the little masses of new
tissue which form in the lungs where the tu-
bercle bacilli are, are not well supplied with

THE STORY OF THE BACTERIA. 75

blood, and for this and other reasons they are
apt to become friable and break down, and
then little particles of them are apt to be
coughed up and discharged in the sputum.
But this broken-down material frequently con-
tains large numbers of living tubercle bacilli.
Now, if the material which consumptive per-
sons cough up and spit out were always de-
stroyed at once by being burned or received
into a dish of carbolic acid or some other effi-
cient disinfectant or germicide, one of the
greatest dangers of the spread of the disease
would be removed. But unfortunately this is
in fact very rarely done. Thousands of con-
sumptives are walking about the streets of our
large towns or visiting places of assembly, who
discharge the infectious material coughed up
from the lungs upon the pavements or floors.
This dries, and shortly is ground up, and takes
its place among the rest of the floating du^t of
the air.

Essentially the same thing takes place in
rooms in which consumptives are confined if
intelligent precautions are not taken to destroy
or convey away the discharged material. It

76 THE STORY OF THE BACTERIA.

has been found by actual experiment that a
considerable number of living tubercle bacilli
may be lodged, together with other dust par-
ticles, high up on the walls of hospital wards
in which consumptives are unintelligently
cared for, in situations to which they could
have been conveyed only through the air as
ordinary dust is. The same material allowed
to dry on handkerchiefs may in a similar way
become a source of danger, not only to others,
but may cause a fresh infection of the patient
himself.

It is very important to remember that it is
only when this discharged material is allowed
to dry that it, under ordinary circumstances,
becomes a source of infection through the air.
Bacteria never rise from thoroughly moist
surfaces. One might spread a thick layer of
living bacteria of any kind, no matter how in-
fectious, over an exposed surface, and, pro-
vided it was kept thoroughly moist, might
breathe with impunity the air sweeping in
strong currents over it, because the germs
always cling most tenaciously to such surfaces.
Of course a current of air strong enough to

THE STORY OF THE BACTERIA.

sweep the particles of fluid bodily off from
their position would be efficient in spreading
the infection. The important point which this
statement emphasizes is that the breath of tu-
bercular persons is not infectious ; the air itself
passing over the moist surfaces of the respira-
tory passages and the mouth carries no germs,
The act of kissing, however, might lend itself
most efficiently to the transmission of the
infection.

Now all these facts are extremely disagree-
able both to hear about and to tell, and they
can only be infinitely distressing to the victims
of tuberculosis and to their friends and associ-
ates ; but all the same they are facts, stubborn,
abiding, and significant. The sooner we rec-
ognize the truth that every consumptive person
may, if proper precautions are not taken, be an
actual and active source of infection, not only to
those who immediately come in contact with
him, but to those who, either where he is, or
where he has been, are forced to breathe dust-
laden air, the better will it be for all concerned.

Now of course no intelligent person would
infer from this statement of facts regard-

78 THE STORY OF THE BACTERIA.

ing the sources of infection with tubercle
bacilli through the air, that everybody who
goes upon the street or enters a hospital or
a theatre is going, or is even liable, to ac-
quire tuberculosis. For, in the first place, the
infecting material, even under the worst con-
ditions, is enormously diluted by the circu-
lating air, so that the individual chances of
coming in contact with the dangerous material
are slight. In the second place, the average
healthy individual is not predisposed to the
disease at all, and could be affected only under
especially favorable conditions. Third, the
amount of infecting material is apt, in trans-
mission by the air, to be small, and this is a
condition which diminishes the chances of
danger from such exposure. Finally, every indi-
vidual has in his respiratory tubes an arrange-
ment of tiny cells whose free surfaces are cov-
ered with little hair-like processes called cilia.
These are ceaselessly waving to and fro, and
tend to sweep up and away from the lungs for-
eign particles which may be breathed in with
the air. But notwithstanding all these condi-
tions which serve to guard the exposed indi-

THE STORY OF THE BACTERIA. 79

vidual against the disease-producing bacteria,
it still remains true that no man can acquire
tuberculosis without getting into his body this
particular bacillus from some infected individ-
ual or animal.

The Bacillus tuberculosis can be cultivated
artificially in the laboratory on potatoes or
other solid media, provided the surfaces are
kept always moist and the temperature kept
approximately at that of the human body. It
does not grow in nature outside of the human
or animal body, but it may remain alive for a
long time, even in the thoroughly dry condi-
tion, and ready to grow again when it gets into
the body under favorable conditions.

The conclusions which almost thrust them-
selves upon us from what we have thus learned
about tuberculosis are very plain. Tubercu-
lar cattle ought to be killed at once and
their carcases burned or otherwise rendered
innocuous just as soon as the disease is
discovered, and never allowed to get into the
markets. Pecuniary losses which individuals
might thus suffer are not worthy of a moment's
consideration as weighing against such obvi-

8O THE STORY OF THE BACTERIA.

ously necessary preventive measures. These
ends ought to be secured first by a more rigid
inspection of cattle and of meat on the part of
authorized persons, and second by the enact-
ment of such laws as would secure for persons
who knowingly sell tuberculous meat or milk
for food such penalties as they would incur
from any other form of purposed or care-
less poisoning of their fellow-men.

It would be very difficult to stop by any sort
of legal enactment the spread of the tubercle
bacilli by means of the air from man to man.
But a thorough acquaintance of all persons
with the fact that a consumptive patient may
be a source of actual danger to all about him,
unless the proper precautions are adopted,
would do much to lessen the evil.

Steamship and railroad companies should be
obliged to furnish separate accommodations for
persons thus affected, so that no well person
should ever be forced in the exigencies of
travel to expose himself to the liability of
infection.

Such regulations and discriminations as are
here suggested would of course often be

THE STORY OF THE BACTERIA. 8 1

extremely annoying to the victims of the
disease and their friends as well as to all
immediately concerned. But some such under-
standing must be come to, unless people are to
go on needlessly dying from this most im-
portant disease.

The best way of disposing of the sputum oi
consumptive persons, which, if allowed to dry,
may, as we have seen, become the source of
active danger to himself as well as to others, is
by burning.

It may be received into small cheap wooden
or pasteboard boxes, which are now made and
sold very cheaply by the druggists, and which
at frequent intervals, together with their con-
tents, should be burned in the stove, furnace,
or fireplace. When handkerchiefs or cloths
are used to receive the material coughed up,
these should be either burned as early as
possible, or soaked for several hours in a five per
cent, solution of carbolic acid and then boiled
and washed. But the use of handkerchiefs and
cloths is to be avoided for this purpose as
much as possible, because they afford most
favorable conditions for the drying and distribu-
tion of the infectious material.

82 THE STORY OF THE BACTERIA.

But while we are thus led by the knowledge
which has been gained of the tubercle bacillus
to a more precise notion as to what should be
done to prevent the spread of the disease,
what has the accumulated lore to offer of hope
or comfort to those already stricken. In the
first place, the physician can now say positively
by finding the bacilli in the material discharged
from the lungs, in many cases even in very
early stages, that the lung is diseased : and we
now know that consumption is by no means a
hopeless disease, especially if it be detected in
its early stages. We know that the cells of the
body, if they are in a properly active and vig-
orous condition, have a tendency to destroy the
germs. And in a great many cases the wise
physician may, by recommending changes of
climate, improved conditions of hygiene,
proper exercise and food, as well as by the
giving of sustaining and strengthening medi-
cines, hold out to his patient a good hope of
ultimate recovery or of prolonged and com-
fortable life.

We battle to-day at any rate with a known
and comprehensible foe, and no longer grope

THE STORY OF THE BACTERIA. 83

in the dark after a mysterious and unknown
enemy. The hope of the enlightened physi-
cian looks out towards a time when we may
have learned some direct and efficient means
of destroying the invading germs in the body,
but, in the meantime, by aiding the body's
inherent means of cure, he feels himself no
longer helpless, and is grateful for so much aid
as scientific research, as yet, has furnished him
in dealing with this dread disease.

CHAPTER VIII.

BACTERIA AND TYPHOID FEVER.

TYPHOID fever is one of the serious and
common diseases, occurring among all
classes of people, which is definitely known to
be caused by bacteria. The germs causing
this disease are little rods or bacilli considera-
bly larger than those which cause tuberculosis.

There are several forms of low fever, and
some other diseases due to various causes,
which considerably resemble typhoid fever, and
are not infrequently mistaken for it. But genu-
ine typhoid fever is caused by this particular
germ, and no other, and is never caused in
any other way.

This typhoid bacillus is not known to grow
outside the body, to any considerable extent
at least, except when artificially cultivated by
the biologist for purposes of study. But it
may remain alive for a good while outside the
body in water or under other conditions.

84

THE STORY OF THE BACTERIA. 85

The typhoid germ, in the large majority of
cases, attacks the body through the intestinal
canal. When it gets into the intestines, if in
sufficient quantity and the conditions are favor-
able, it multiplies, and enormous numbers
of the germs are thus produced. Some of
these gain access to certain of the other inter-
nal organs, but most of them either complete
their existence in the intestinal canal, or are
cast out in the living condition with the diar-
rhceal discharges which so constantly accom-
pany this disease.

It seems most probable, from what we know
at present about the action of the typhoid
bacilli in this disease, that, as they grow and
multiply in the bowels, they produce a soluble
poison — ptomaine, — which is absorbed, just as
some kinds of food might be, and carried to
various parts of the body, producing effects
which we recognize as symptoms of the disease.
The bacteria themselves remain, as it would
seem, for the most part, in the intestinal canal,
to pass off in the discharges.

The great and important source of infection
—the means by which the disease is usually

86 THE STORY OF THE BACTERIA.

spread — is these discharges from the bowels,
containing the living, virulent typhoid bacilli.

Here, we have an essentially similar con-
dition of affairs to that in tuberculosis, namely,
bacteria of a particular species causing a dis-
ease which, without them, could not or does
not, so far as we know, exist, and after in-
ducing the disease in an individual, being
discharged alive and virulent from the body.
Here, as in tuberculosis, although the mode of
infection is somewhat different, if all the dis-
charges from persons suffering from the dis-
ease could be immediately destroyed by car-
bolic acid or corrosive sublimate, all danger of
infection, so far as we know, would be removed.
Typhoid fever is thus a preventable disease.

So far as we know, typhoid fever affects
man alone, and he alone forms the source of
infection. But, unfortunately, the bacteria are
not generally destroyed, and the house-mates
of the patient, or those who use the same water
supply, or are dependent upon the same food
sources, or subject to a connecting and defec-
tive sewage system, now and then are liable,
through food, or water, or air, to take into the

THE STORY OF THE BACTERIA. 87

intestinal canal some of the tiny germs, not
larger than the motes in the sunbeam, but
bearing in them the seeds of disease, or even
death.

Altogether the probabilities are that in the
majority of cases the typhoid-fever germs are
most frequently carried and consumed in water
which has in some way been polluted by
human waste containing the typhoid germ.

It seems quite incredible, when put down in
black and white on paper, that responsible and
sane persons of ordinary intelligence, knowing
that typhoid fever is caused by a living germ,
knowing that this is thrown off from the body
in the living condition and without being
destroyed, is allowed to run through the
sewer pipes into the nearest stream or lake,
should for an instant consent to have the
water of this stream or lake taken from
within a short distance of the sewer opening,
and often in line of direct current, and
distributed in their houses unpurified, and
used upon their tables. And yet it would be
but the telling of old stories for the writer to
cite case after case in which this offence against

88 THE STORY OF THE BACTERIA.

common decency, to say nothing of good
taste, is practised under conditions much more
flagrant than these. And then Providence or
Fate is shouldered with the responsibility
when the careless or ignorant persons them-
selves, or the innocent victims of their criminal
neglect, are stricken with typhoid fever.

There is little doubt that the typhoid-fever
bacilli sometimes enter houses from sewer
pipes containing them, owing to defective
traps or leaks in the pipes. Sewer gas is in
itself a very bad thing to have pouring into
houses, and is capable of inducing a great
variety of disturbances of health, some of
which are very serious indeed, but sewer gas
alone cannot induce typhoid fever. For that
the bacillus itself must be present. It is prob-
able that when the traps are allowed to get
dry, as no doubt often happens in shut-up city
houses during the summer, currents of sewer
gas sweeping up through the pipes, on whose
walls the typhoid bacilli have collected, may
dislodge these, if the sides of the pipes are
dry, and carry the germs as floating dust
into the rooms, where they may settle, and

THE STORY OF THE BACTERIA. 89

finally, sooner or later, gain access to the food
or drink of the inmates. This mode of con-
veyance of the germ of typhoid fever has not
yet been proven, but, as a reasonable hypothe-
sis, is closely in accord with what we know but
too well of the outbreaks of typhoid fever
which so often occur on the return of house-
holds in the autumn to their city homes.

It has been abundantly proven by careful
experiments that the typhoid bacillus can re-
main alive for long periods when frozen solidly
in a block of ice. The disease-producing bac-
teria which may be conveyed in ice in impure
water to the body will be considered in a sub-
sequent chapter.

CHAPTER IX.

THE RELATIONS OF BACTERIA TO ASIATIC
CHOLERA.

HISTORY records many tragic stones of
sudden outbreaks of fatal disease which
spreading like wildfire among the people have
brought untold miseries and countless deaths.

In early times these frightful whirlwinds of
disease were looked upon as penal visitations
of the Supreme Powers, and in the utter panic
which they so often induced little was done in
the way of studying their nature or staying
their progress.

Among the more important of these tragic
epidemics which have been experienced and
carefully observed since science has withdrawn
the veil of superstition from them, stands Asi-
atic cholera.

In some parts of the world this disease is
constantly present and claims each year a vary-

90

THE STORY OF THE BACTERIA. 91

ing number of victims. But Europe and Amer-
ica are in general free from it, save that now
and then coming from its home in the far East
it sweeps along the seaboard or over the coun-
try, bringing in a greater or less degree the old-
time panic and misery and death in its train.
Occasionally it finds lodgment upon our own
shores and has penetrated into the interior.

Now up to within a few years we have not
known what the cause of this disease really
was. It seemed to be something which could be
brought in ships and wrapped up in clothing,
and was evidently communicable from man to
man. Such measures of stopping the spread
of the disease by isolating the sick, and such
general regulation of the diet and habits as
seemed from experience best adapted to pro-
tect the well, were formulated and practised.
But the utter lack of knowledge as to the exact
nature of the contagion frequently rendered
futile the one and uncertain the others.

To-day we know that Asiatic cholera is
caused by a little curved bacillus, which on
getting into the intestinal canal of human
beings multiplies with such rapidity that

Q2 THE STORY OF THE BACTERIA.

within a few days or hours the body may
be overwhelmed with the poisonous material
which it eliminates as it grows. We know
that in certain stages of the disease the liv-
ing germs are discharged from the body in
vast numbers, and that if moisture be present
they may remain alive outside of the body for
long periods and may even multiply. They
can thus remain alive for some time in water
and on the moist surfaces of vegetables and
fruits and clothing.

There is no good reason for believing that
any other germ or organism than this particu-
lar curved bacillus ever induces Asiatic cholera,
or that the disease is ever caused by any thing
else. The only known way in which the infec-
tion is conveyed from man to man is by the
taking into the intestinal canal, either by water
or food or in some other way, some of the
cholera bacilli which have come directly or indi-
rectly from some human victim of the disease.

The germs may remain alive for a long time
if kept moist, and so the disease may be con-
veyed for long distances in bundles of infected
clothing. A few hours of thorough drying or

THE STORY OF THE BACTERIA. 93

steaming-, or the application of suitable disin-
fectants, such as strong carbolic acid or corro-
sive sublimate, readily secures total destruction
of the life of the germs.

In Asiatic cholera, as in all of the other
bacterial diseases which we have thus far
studied, predisposition of the individual is an
important factor in the acquirement of the dis-
ease. This simply means that there are cer-
tain conditions of the body cells which render
them less able to resist the incursions of for-
eign organisms like the bacteria, or which fur-
nish conditions favorable to their growth and

o

proliferation.

We have seen that in tuberculosis this pre-
disposition to the disease, whatever its exact
nature is, may be in marked degree hereditary.
In Asiatic cholera a disordered condition of
the digestion appears to favor the occurrence
of an attack of the disease. In typhoid fever,
analogous predisposing factors seem to deter-
mine that when exposed to the same risk of
infection one individual may be attacked with
the disease and another not. But alike in all
these forms of bacterial disease the particular

94 THE STORY OF THE BACTERIA.

species of bacteria belonging to each must be
present, predisposition or no predisposition, or
the disease cannot occur.

Typhoid fever and cholera are often called
filth diseases, and to bad food, foul air, sewer
gas, and overcrowding their occurrence has
often been attributed. This is in a sense true,
since these adverse conditions are apt to induce
a state of the body which renders it less resist-
ent than it should naturally be to various dele-
terious agencies ; but no imaginable degree of
unsanitary conditions could ever induce tuber-
culosis, or typhoid fever, or Asiatic cholera
without the presence of the particular germ
which causes each. None of these diseases
can spring up among any class or condition of
people without the introduction of the germ
from outside.

The recently acquired knowledge of the
cause of Asiatic cholera has thus far aided but
little in the treatment of persons already its
victims. On the other hand, knowing defi-
nitely, as we now do, what causes the disease,
how and under what conditions it spreads, and
what will destroy the germs, we are to-day in

THE STORY OF THE BACTERTA. 95

a condition, wherever sanitary and proper
quarantine regulations are efficiently carried
out, to largely prevent the access of the dis-
ease to our country, to stay the progress of an
epidemic at its very outset, and to promptly
allay the panic which the advent of a mysteri-
ous and deadly scourge is so prone to incite

CHAPTER X.

THE RELATION OF BACTERIA TO DIPHTHERIA,
PNEUMONIA, SCARLET-FEVER, ETC.

THERE are several diseases besides those
which we have considered in some de-
tail which are proven to be caused by the
entrance of bacteria into the body. There is
a still larger number which we believe, and
with the very best of reasons, to be caused by
bacteria, but from which the germs have not
yet been isolated and carefully studied so that
we can speak positively about them.

Diphtheria.

Diphtheria is one of the most dreaded of
the diseases, especially in childhood, which are
known to be caused by bacteria. We are not
yet quite certain whether it is always caused
by one form of germs, or whether in the differ-
ent outbreaks or in different regions sometimes

0

1 UNIVERSITY )

THE STORY OF THE ^S^£S£it^^ 97

one and sometimes another species induces
the disease.

It has been shown that diphtheria, as it oc-
curs in children's asylums in New York, may
be caused by a streptococcus, which, when it
gets into the mucous membranes of the air
passages, especially if these are already in an
inflamed condition, can produce those local
changes which are so well known to accompany
this serious disease.

It has been furthermore shown that these
streptococci may remain alive for long periods,
when thoroughly dried, as in the dust, and it
has been found in the living and virulent con-
dition floating in the dust of the air of rooms
in which children suffering from diphtheria
were confined. It has been found in the
mouths of children who had been exposed to
the disease, and very soon after some of these
children suffered from serious and fatal attacks
of diphtheria. This bacterium has been shown
to be readily killed by moderately strong solu-
tions of carbolic acid and corrosive sublimate.

It is very well known that if the membranes
which are so apt to stop up the air passages in

98 THE STORY OF THE BACTERIA.

diphtheria, when in the fresh condition, come
in contact with the mouths or air passages of
healthy persons, they may set up the disease.
This is because the material composing the
membranes may contain large numbers of the
living, virulent germs. It is furthermore known
that the poison of diphtheria may linger for long
periods in rooms where the disease has occurred,
and may be conveyed on the clothing of per-
sons who have come in contact with the sick.

Now in this, as in the other bacterial dis-
eases which we have studied, if all the material
which is cast off and discharged from the body
were at once received into strong disinfecting
solutions or burned, so that the germs might
be killed, the disease would have little tendency
to spread. But if, as is too often the case, the
discharged particles are allowed to collect on
handkerchiefs, or bedding, or clothing, or on
the floors, they dry and finally become ground
up and mingle with the dust, and as the germs
are not killed to any great extent by the dry-
ing, when the dust is inhaled it may, if the
individual be in a favorable condition for its
development, grow and induce the disease.

THE STORY OF THE BACTERIA.

It is not unlikely that the dried diphtheria
germ may, from faulty plumbing or dry traps
in the pipes, be blown into rooms along with
the sewer gas, and that thus the disease is
sometimes communicated without direct con-
tact with an infected person.

Pneumonia.

Pneumonia, in its more common phases, is
another of the diseases which we believe to
be caused by bacteria. The germ which pro-
duces the trouble has been many times sepa-
rated and carefully studied. It is called the
Pneumococcus.

So frequently does this disease follow ex-
posure to cold or wet, and so often does it
begin with symptoms which resemble those of
an ordinary cold, that it was long believed to
be, and still is popularly regarded, as usually
caused by these exposures. But most of those
who have carefully studied the disease by the
use of the modern scientific methods of re-
search are disposed to believe that the expos-
ure to cold and wet and other less well-defined
conditions which were formerly regarded as

100 THE STORY Of THE BACTERIA.

actual causes, while exceedingly important, are
yet simply predisposing factors. They believe
that the reason why pneumonia is so frequently
associated with these conditions is that they
in some way fit the lungs to be a good grow-
ing place for the germs if at the favorable
moment they gain access to them through the
mouth.

We do not know much about the bacteria
which thus appear to cause pneumonia, so far
as their lurking places outside of the body are
concerned. But they are not infrequently
found in the mouths of healthy persons, and
are most likely distributed through the air with
the dust.

The pneumonia which so frequently comes
on as a serious complication of diphtheria has
been shown to be caused by the germs which
cause the diphtheria itself getting down into
the lungs and producing their poisonous effects
there.

Scarlet-Fever, Measles, Yellow-Fever, etc.
There is a great deal in the nature and mode
of communication of scarlet-fever, measles,

THE STORY OF THE BACTERIA. IOI

whooping-cough, and small-pox which indicates
that they too are bacterial diseases ; but the
specific organisms causing them have not yet
been identified. So that in attempting to
guard against their spread we are at present
obliged to make what use we can of the facts
which we know about the proven bacterial
diseases and the experience which has been
accumulated by physicians who so long and
faithfully have studied them at the bedside.
Against small-pox, however, we have a most
efficient safeguard in vaccination, although we
do not yet know the reason for the marvellous
protective effects of the procedure.

Yellow-Fever.

Yellow-fever is a disease of the utmost im-
portance in some parts of our country, about
the cause of which we are almost entirely in
the dark. Our knowledge of it is largely con-
fined to the characters of the disease as it is
seen at the bedside, and to the general con-
ditions under which it is liable to occur and
spread. In many respects it resembles the
known bacterial diseases, in others it differs

102 THE STORY OF THE BACTERIA.

considerably from them. The attempts which
have thus far been made to find bacteria to
which it seems likely that it may owe its origin
have not been successful, although several
claims in this direction have been widely pub-
lished.

Malaria.

Malaria, in its protean phases, has been
thought by many to be caused by bacteria, but
the reliable observations thus far made do not
appear to support this view. There are pecul-
iar minute organisms very constantly found
in the blood in certain stages of malarial
poisoning which may ultimately prove to be
the cause of the attacks. But as this is not
yet definitely settled, and as at any rate the
suspected organisms are not bacteria, but be-
long in that lowly group of animals called
protozoa, we need not consider them further
here.

CHAPTER XL

IMPURE FOOD AND AIR AS SOURCES OF BAC-
TERIAL INFECTION.

AS we glance back over the ground which
we have traversed together, we see that
the most common bacterial diseases which in
this country we are apt to come in contact
with, so far as they are definitely known to us,
are tuberculosis, typhoid fever, diphtheria,
pneumonia, and the wound diseases or blood
poisoning.

We have seen that in most of these diseases
the poison is liable to spread from one indi-
vidual to another, because it is not destroyed
by disinfectants, or in some other way, as soon
as possible after it is discharged from the dis-
eased person.

We have seen that the most common ways
in which the virulent bacteria are spread are
by the air we breathe, the food we eat, and

103

104 THE STORY OF THE BACTERIA.

the water we drink. If any of these necessi-
ties of life contain in them the living germs of
these diseases, there is a liability of the infec-
tion of healthy or predisposed individuals.

The liability to acquire these diseases is
always increased in direct proportion to the
crowding together of the sick and the well
under unsanitary conditions in large communi-
ties. This is not because filth and dirt are in
themselves infectious, but because pathogenic
bacteria are liable to become mingled with the
rest. In other words, there is a simply filthy
filth, and there is a pathogenic filth, and the two
are very apt to go together.

No gas, however foul, no accumulation of
dirt, no degree of malnutrition or misery or
overcrowding can induce an infectious disease.
It is always and everywhere some particular
form of disease-producing germ which causes
the trouble. The other influences bear largely
upon the chances of incurring the disease, and
often determine the severity of its course or
its fatal ending, but they alone cannot cause it.

In considering what ought to be and what
can be done to prevent the spread of the bac-

THE STORY OF THE BACTERIA. 1 05

terial diseases, it is evident at once that there
are two distinct classes of preventive measures :
first, those which must be arranged and en-
forced by the public authorities, such as
Health Boards and their officers ; and second,
those which depend upon the intelligence,
knowledge, and faithfulness of private indi-
viduals. It does not lie within the scope of
this little book to consider, except incidentally,
the measures which should be taken by the
authorities on the large scale, to ward off epi-
demics or to secure proper sanitary conditions
among the people.

It is not, in fact, the great and sweeping
epidemics, dramatic and frightful as they are,
which carry off prematurely the largest num-
ber of people ; but it is the bacterial diseases
which we have constantly with us, and to which
we have become so accustomed that we do
not usually realize their vast importance, and
against which systematic and persistent cru-
sades on the part of the health authorities are
only occasionally and fitfully undertaken.
Among the bacterial diseases which are well
understood, the most important, in some re-

106 THE STORY OF THE BACTERIA.

spects, in this country are tuberculosis, typhoid
fever, and diphtheria.

The danger of infection with disease-pro-
ducing bacteria which we may encounter in
the ordinary paths of life lurk, as we have
seen, for the most part, either in food, or air,
or water. Let us now look at these sources
of danger a little more closely.

Impure Food as a Source of Bacterial Infection.

We have seen that the meat of tubercular
cattle and the milk of tubercular cows, and
the same is true of tubercular fowls, may con-
tain the living tubercle bacilli, and that if the
meat be not thoroughly cooked and the
milk not thoroughly boiled, these germs may
get into the intestinal canal, and cause dis-
ease. The remedy here lies in part in the
hands of the health officers, or, when their
efforts fail, in the hands of the consumer him-
self. A much more rigid inspection of cattle,
with full authority to destroy all infected herds,
should be at once established. It should be
thoroughly understood by every householder,
that if this be not done, uncooked meat, of

THE STORY OF THE BACTERIA. ID?

whatever kind, should be altogether avoided ;
and the same should apply to milk. The boil-
ing of milk for from three quarters of an hour
to an hour suffices to kill the germs of tuber-
culosis.

Scarlet-fever and diphtheria may also, as
has been abundantly proven, be transmitted
by milk which has in any way been exposed
to the infection ; and hence the thorough
boiling of milk, in cities where the source of
the supply is not definitely known, would be a
wise precautionary measure.

Milk is such an excellent food medium for
the greatest variety of bacteria of nearly all
species, that although bacteria-free when it
comes from the cow, it may, before it reaches
the consumer, contain several millions of liv-
ing germs to one teaspoonful. Now it has
been found that milk which contains a great
many bacteria, although these may not be of
a kind which ordinarily produce any well de-
fined disease, may in young children produce
digestive disturbances and diarrhoea, which is
often of a very serious character. Milk from
the ordinary unknown sources of supply ought

108 THE STORY OF THE BACTERIA.

therefore to be thoroughly boiled before it is
fed to infants and young children, and very
simple and inexpensive forms of apparatus for
this purpose have been devised and can be
recommended by any well informed physician.

As the germs of various diseases may be
floating in the air, especially in densely popu-
lated regions, all fruits, vegetables, and salads
ought to be thoroughly washed before they
are eaten, unless they are to be cooked. The
exposure of such articles of food on the side-
walks in cities, as is so often done, is a most
reprehensible practice, and this alone should
be enough to decide the householder to dis-
pense with the supplies of any dealer who per-
sists in it.

There is no doubt that the germs of typhoid
fever, and, when it is prevalent, those of Asiatic
cholera, are conveyed from one to another by
means of food on which in some way the
germs from the discharges of sick persons
have lodged. This is of course most apt to
occur among the poorer classes in large towns
whose market-stalls are the gutters, and whose
living-rooms, alike for sick and well, may

THE STORY OF THE BACTERIA. 1 09

serve at once as kitchen, dining-room, garbage
reservoirs, and bedchambers. But among
those more fortunately circumstanced, the con-
veyance of the diphtheria, and probably of
typhoid-fever germs, on uncleansed spoons,
dishes, etc., is of no infrequent occurrence.

The Air as a Source of Bacterial Infection.

We have seen that the only way the air
which we breathe can be actually infectious, that
is, can be the means of transmitting a bacte-
rial disease, is, under ordinary conditions, by
carrying as dust the dried but living disease-
producing germs from some infected individual
or animal along with other and less harmful
dust. Thus it is that our recently acquired
knowledge of bacteria and other minute or-

o

ganisms has brought a new significance into
the problems of ventilation. Foul air we still
know to be bad and capable of inducing seri-
ous forms of disease, but the specific and most
significant elements of positive danger reside
in the floating dust.

The possibility of taking the bacteria of
tuberculosis and diphtheria into the mouth

110 THE STORY OF TffE BACTERIA.

and lungs with the air out-of-doors, especially in
large cities, is, as we have already seen, imminent
and widespread, but ordinarily the dilution of
the dangerous elements is so great as to reduce
greatly the chances of evil effects from swal-
lowing or inhaling them. But still, in large
towns, whose streets are not faithfully cared
for, the probability of being obliged to pass
through clouds of dust whenever one goes
upon the streets, especially in the windy sea-
sons, is very unpleasantly suggestive of dan-
ger, and more than suggestive of filth.

In New York, even in districts where the
streets are measurably frequently attended to,
the insufficient watering of the pavements be-
fore the street-sweepers pass, the long periods
which often elapse before the dirt heaps are
carted off, and the reckless way in which the
dirt is shovelled into the carts, are all evi-
dences of carelessness which greatly increases
the risk of street infection, and abuses which
ought to be at once corrected.

But, after all, it is in living-rooms and in
places of assembly that we must look for the
most frequent sources of danger. While, as

THE STORY OF THE BACTERIA. Ill

we have seen above, there is a certain heredi-
tary predisposition to tuberculosis which is
resident in the body cells themselves and of
the exact nature of which we are quite igno-
rant, there is little doubt that one of the most
important reasons why tuberculosis is apt to
run in families is that children and relatives of
consumptives are more liable than others to
come in direct contact with the disease-pro-
ducing germs, which have been thrown off
from the bodies of their house-mates under
conditions which permit of their drying and
inhalation as dust.

Theatres and churches, especially the
former, are apt, as is well known, to be alto-
gether inadequately ventilated. The headache
and malaise which are so prone to follow a
visit to many of our theatres, are evidences of
the bad air which we are usually forced to
breathe there ; but the more subtle dangers
here, as elsewhere, lurk in the dust which
equally with the bad air is forced upon us.

No adequate means exist in most theatres
for ridding the air of the dust. The best of
them indeed are swept and " dusted " system-

112 THE STORY OF THE BACTERIA.

atically and the larger particles of dirt collected
and removed ; but the floating dust is simply
stirred up, and after settling is stirred up again
by the so called duster, and so partially
removed from the seats, but it settles again
on the floors, to be again set in motion by the
entering and retiring audience. It would be
safe to say that the only systematic mode of
removal of the floating dust from many of our
popular theatres and churches is by its lodg-
ment in the throats and lungs or on the
clothing of the people who visit them.

Some of the newer theatres are furnished
with improved and sufficient ventilating appa-
ratus, but some of them are not, and while we
admire the chaste gilding and sumptuous up-
holstery of the interior, and complacently
reflect that at length the law has forced
builders of places of amusement to afford a
measurable degree of security against being
burned alive, that element of danger in large
assemblies, more important and more subtle
than all the rest put together, namely, inade-
quate ventilation, is rarely commented upon or
thought about. There ought to be definite

THE STORY OF THE BACTERIA. 113

regulations for all public assembly-rooms,
which should insure the forcing of a proper
amount of fresh air through them, which would
not only carry off foul air, but much of the
floating and possibly infectious dust with it.

In dwelling-houses, the problem of ventila-
tion is in many respects simpler than in large
assembly-rooms, because to a certain extent the
householder is aware of the possibilities of
dust infection, from the condition of health of
the inmates, and can act accordingly. But
even here, under ordinary conditions, there
seems to be, from what we have learned about
the bacteria, more reasons than we have
before appreciated for securing adequate ven-
tilation— such ventilation as shall carry off not
only the used-up air but the floating dust.

The ordinary practice of occasionally stirring
up the settled dust with a feather-duster should
give place to the use of moist cloths or dry
cloths frequently shaken out-of-doors, so that
the dust may be removed and not simply
redistributed. This becomes the more impor-
tant if any inmate of the house is suffering
from one of the bacterial diseases.

114 THE STORY OF THE BACTERIA.

In the interests of health the fitting of houses
with simpler furniture or less heavy hangings
and fixed carpets is greatly to be desired.

The regulation of the sick-room, and its
communication with the rest of the house, is a
matter on which the advice of the physician
should be sought. First and foremost should
stand the systematic and careful destruction of
the infectious material in all discharges of what-
ever sort from diseased persons, by burning or
by the proper disinfecting solutions such as five
per cent, carbolic acid. In this solution the dis-
charges should be allowed to soak for several
hours before they are thrown into the sewer or
otherwise disposed of. As to the cleansing o{
rooms after their occupancy by persons who
have suffered from bacterial diseases, direc-
tions should be obtained from the physician or
from the health authorities.

The danger of infection with the germ of
tuberculosis through the air is very widespread,
because consumptive persons are often for long
periods not confined to their houses, or rooms,
or beds, but may be more or less active centres
of infection by mingling with the well in all the

THE STORY OF THE BACTERIA.

ordinary walks of life. We have seen already
by what comparatively simple means a large
part of the danger of the spread of tuberculosis
and diphtheria might be prevented. The risk
of dust infection from diphtheria, and probably
from other somewhat similar diseases, such as
measles and scarlet-fever, is more apt to be
limited to rooms or houses where the disease
has occurred, because the victims of these dis-
eases are usually sick enough to be confined to
the house or bed. But there are, as all physi-
cians know, frequently enough cases of these
diseases in which the patients go about among
their fellows throughout the whole course of

o

the illness, or at least for some time after it is
fully established.

The possibility of dust infection with any
of the diseases which we have been consider-
ing, emphasizes the importance of breathing
through the nose and keeping the mouth shut
except when it is necessary to have it open.

CHAPTER XII.

IMPURE WATER AND ICE AS A SOURCE OF
BACTERIAL DISEASE.

Impure Water.

WE have seen in another part of this
book that natural surface waters always
contain considerable numbers of living bacteria
of various kinds, which are growing and pro-
liferating there, and no doubt actually purify-
ing the water in a certain way by feeding upon
and removing from it organic material which
has collected or been dissolved. Now these
bacteria in moderate numbers, under ordinary
conditions, are not at all harmful to the con-
sumer of the water for drinking or culinary
purposes.

But, on the other hand, if the water
becomes stagnant and the ordinarily harm-
less bacteria collect in very large numbers, it
has been abundantly shown by most bitter

116

THE STORY OF THE BACTERIA.

experience that the use of the water may give
rise to serious or even fatal acute disorders of
the digestive system. Cholera morbus and
the so-called winter cholera are apparently
sometimes caused in this way. Young chil-
dren are especially susceptible to the bad
influences of such water, and the boiling of it,
or the change of supply, has repeatedly been
found sufficient to stop attacks of cholera in-
fantum or the summer diarrhoea of young
children.

On the whole, however, the bacteria which
water naturally contains as it is found in lakes,
running streams, and good springs are quite
harmless, unless they are allowed by stagna-
tion to accumulate to a very considerable
degree. We do not yet definitely know to
what extent the ordinary harmless bacteria
might be allowed to accumulate in drinking-
water before it would become harmful. But
the limit is usually somewhat arbitrarily placed
at present at from three hundred to five hun-
dred to the teaspoonful.

The frequent real and serious dangers from
impure drinking-water do not lie in the bacte-

118 THE STORY OF THE BACTERIA.

ria which naturally occur there at all, but in
those which get into it from outside, through
pollution by the waste from animals and
human beings, and especially from human
beings who are the victims of some bacterial
disease.

Polluted water may convey the bacteria
which cause Asiatic cholera, and the same is
true for diphtheria or the wound diseases,
and doubtless many others, but the spread of
these latter diseases in this way is no doubt
quite infrequent.

It is typhoid fever, whose germs, of all
those which cause disease, are, so far as
we now know, most apt to be spread by pol-
luted water. The discharges from persons ill
of typhoid fever, thrown without disinfection
into the vaults of country or village out-houses,
— which, in an appalling number of cases, are
in direct communication, through underground
channels, with the wells, or with springs from
which the farmer supplies the family or guests,
—may pass, with but a very moderate dilution,
into the digestive tracts of the unsuspecting
victim. It is ignorance, not Providence, which,

THE STORY OF THE BACTERIA. I IQ

under these conditions, determines an epidemic
of typhoid fever.

The water supplies of large towns come, for
the most part, either from large rivers, or lakes,
or artificial reservoirs along the course of
smaller streams, or from artificial wells, which,
piercing the upper strata, gain access to the
deep underlying collections. Now in the sur-
face water supplies, as from rivers or from
lakes, man is his own worst enemy, because
the most serious dangers from impure waters
arise from its contamination with human waste.

Many great water supplies, which, under
ordinary conditions are good, are constantly
liable to become sources of danger, because
the sewage from dwellings is discharged, if
not into them, still, so near to them that it
may now and then enter, being washed in by
rains or in some other way. This, under
ordinary conditions, may, if the sewage be
largely diluted in the reservoirs or streams, be
simply disgusting and filthy, though not posi-
tively dangerous. But if, as is at any time
liable to happen, typhoid-fever discharges get
into the waste-pipes and so into the water, the

120 THE STORY OF THE BACTERIA.

danger of the spread of this disease becomes
of great importance.

The great water supply of the city of New
York, the Croton, is of this character. The
water comes from a large territory known as
the Croton water-shed, and is naturally a very
good water supply indeed ; but along the
streams and reservoirs which collect the water
are numerous villages and scattered dwelling-
houses. While some attempt is made to keep
the banks of the water-ways free from sources
of sewage and waste contamination, as they
are largely private property this is not ade-
quately done, and at any time an epidemic of
typhoid fever in houses or villages along the
Croton streams and lakes would be liable to
cause a dangerous contamination of our city
supply.

There are two ways in which this positive
danger can be obviated. One is by the pur-
chase, by the State, of a strip of land along all
the shores of the Croton water system, and
the removal to a safe distance of all possible
sources of contamination.

Another means of security, which, perhaps,

THE STORY OF THE BACTERIA. 121

in the lono- run would be the most efficient

o

and most thoroughly under control of the
authorities, would be the construction of large
filter-beds, or filtering apparatus, by means of
which the water might be freed from all dan-
gerous contaminations under all conditions. It
will thus be seen that while the Croton water
is not at present a source of actual danger it
may at any moment become so, unless some
efficient means be taken to protect its sources,
or purify it before distribution.

Conditions similar to that of the Croton are
very common in the city water supplies every-
where, in this, as in other countries. And the
more rapidly are the regions from which the
water is derived becoming populated, the more
serious does the danger grow.

Another great source of water supply for
large cities and towns is the rivers on whose
banks they are built. The water is usually
taken at a point some distance above the
town, so as to avoid the sewage of the town
itself, which, as a rule, is allowed to escape
directly into it. But in almost all cases, in
thickly settled countries, there are other towns

122 THE STORY OF THE BACTERIA.

on these streams above the points at which the
water is taken, polluting it with their sewage.
Now so prevalent is typhoid fever all over the
civilized world that the sewage of every large
town is liable to contain greater or less numbers
of living typhoid bacilli.

The city of Albany, N. Y., which takes its
drinking-water from the Hudson River a
short distance above the town, just after it
has received the sewage of Troy and that of
several smaller towns on the banks of both the
Hudson and the Mohawk above, is an example
of a city which relies upon a water supply
always both filthy and dangerous.

Philadelphia is another great city whose
water supply from the Schuylkill River is of
the most dangerous and disgusting character,
from its large admixture of sewage and human
waste. The typhoid-fever statistics of Phila-
delphia are abundant witnesses to the almost
incredible apathy or carelessness of its authori-
ties.

In older countries where the sanitary dan-
gers which always grow with the increase and
massing together of the people have been

THE STORY OF THE BACTERIA. 12$

longer observed and more definitely recog-
nized than in our own, legal enactments have
been long in force to prevent the pollution of
streams which might be sources of water sup-
ply of towns. But still large cities like Lon-
don and Berlin have found it necessary to
further protect themselves against disease-pro-
ducing organisms and against filth, by the
maintenance of filtering systems on the large
scale, by which the dangerous elements of a
contaminated water may be largely or en-
tirely removed.

We should not forget that contaminated
water always tends to purify itself in certain
ways when exposed to the air in large volumes,
as in lakes or running streams. Nor should
we lose sight of the fact that a moderate
amount of sewage, when poured into a large
volume of water, becomes so considerably
diluted, that its dangerous elements are much
less numerous in any given glass or volume
of water than in sewage itself. But such con-
siderations can afford but little real consola-
tion to those who find themselves forced to
drink sewage, even though it be very largely

124 THE STORY OF THE BACTERIA.

diluted. The sewage may contain one hun-
dred thousand typhoid germs to one teacupful,
while the diluted mixture has in it not more
than one to the same volume. But it should
never be forgotten that the one germ is capa-
ble of multiplying in the human body to an
enormous extent, and for this reason, in the
living bacterial poison dilution is of much less
significance than in ordinary poisons which are
not alive and self-propagating.

The fact is, that in view of all that we have
seen of the nature of bacteria and their dis-
ease-producing powers, sewage-polluted water
from wells, or springs, or rivers, or lakes, ought
not to be used for drinking and culinary pur-
poses without some system of purification
which is demonstrably efficient.

The new methods of bacterial analysis of
water, which have been described in the earlier
pages of this book, now enable us to tell with
a great deal of certainty, sometimes with and
sometimes without a chemical analysis, whether
or not a given water has actually been polluted
with sewage, or human or animal waste, and
whether the modes of purification to which it

THE STORY OF THE BACTERIA. 12$

has been subjected, either naturally or artifi-
cially, have actually been efficacious in remov-
ing the living germs.

It is thus evident that upon the intelligence,
knowledge, and fidelity, of the authorities
largely rests the responsibility of pure water
supplies for cities and towns, and the house-
holder is to a large degree at the mercy of
these officials, so far as his protection against
the acquirement of bacterial disease, especially
typhoid fever, is concerned. For it has been
shown over and over again, by the most care-
ful and elaborate experiments and examina-
tions, that the small so-called faucet filters, and
pretty much all the reservoir domestic filters,
do not separate the bacteria from contami-
nated water in a reliable way. The water is
often strained by them and so freed from its
coarser floating particles, and then may appear
quite clear and limpid, and some of the bac-
teria may be at first removed ; but after a
little while not only do these small filters let
the invisible bacteria through their pores in
large numbers, but they may actually afford
breeding- and lurking-places for the living

126 THE STORY OF THE BACTERIA.

germs, — the disease-producing forms among
the rest.

Filtration on the large scale in properly
arranged systems appears to be the only reli-
able way of freeing contaminated water
mechanically from its bacterial ingredients.

Thorough boiling of water for at least an
hour will, however, kill the bacteria, and to
this, in the last resort, the householder must
have recourse when the water supply is justly
suspected to be causing and fostering disease.
This purification of water by boiling may be
done by the householder himself, or, if he can
afford it, he may supply himself with the dis-
tilled and aerated water which is now furnished
in many towns.

But, after all, when the facts about the dan-
gers of a polluted water supply become gener-
ally known, it ought not to be necessary for
the householder to adopt any domestic pre-
cautions against water infection in towns or
cities. If politics, or private or corporate
greed, or general ignorance or apathy stand
in the way of sanitary reform, the outlook for
the water consumer is indeed not encouraging,

THE STORY OF THE BACTERIA. 1 27

but even these obstacles in the way of com-
fortable existence have been and may again be
set aside.

Those who dwell in the country, and those
who repair thither in the summer, should be
very watchful of the water which comes from
the ordinary wells. It is quite true that the
water which soaks into the majority of wells
in the country and in villages has been filtered,
and more or less purified, as it passed through
the soil and earth about the well. But in a
great many cases the surface water runs direct-
ly into the well at the top. Washing is not
infrequently done in the immediate vicinity of
the well, and the waste and dirty water runs
directly, or with but little filtration, back into
the common receptacle. The vaults of out-
houses, barn-yards, and pigstyes are often in
close proximity to the well, on establishments
which in circulars and newspapers figure as
country health resorts. And this is by no means
true alone of those which are inexpensive and
primitive, but almost equally so of many of
the more fashionable and popular resorts.

Every person who goes or sends his family

128 THE STORY OF THE BACTERIA.

into the country in the summer, should per-
sonally inspect the drinking-water supply and
assure himself that it is good. This is actually
of far greater importance than the size of the
rooms, the price of board, or the diversity of
amusements, or any other of the score of
things about which one so scrupulously in-
quires before laying out the summer cam-
paign.

Wells ought to be cemented water-tight for
from eight to twelve feet below the surface.
They should rise several inches above the level
of the surface of the ground, which should be
cemented and made to slope away in all direc-
tions from the opening, so that all drippings
and surface water may be carried off to a dis-
tance of several feet before it soaks into the
ground.

It should always be borne in mind that the
water of ordinary wells is simply surface water,
which has filtered down through the soil, and
collected in the reservoir which the well ex-
cavation makes, and that in closely populated
regions the soil, which originally may have
been efficient as a filter, may finally become so

THE STORY OF THE BACTERIA. I2Q

filthy as not only no longer to cleanse the
water, but to actually infect or contaminate it
as it percolates through.

It is difficult to lay down rules by which the
safety of country and village wells may be
judged. But a very moderate acquaintance
with sanitary principles will usually guide one
to a just opinion. The argument which the
enquirer is most apt to encounter favoring the
salubrity of a country or village well, is that
the owners' fathers and grandfathers drank
water from the well all their lives, and they
and their families lived to a good old age.
But the fact is frequently lost sight of that the
slops and sewage of this long-lived race have
usually been accumulating in the soil about
the house, as the years have sped, and as their
towns and villages have grown the stables and
hog-pens have neared the ancestral roof-tree.
In short, that the sanitary conditions have en-
tirely changed. The fact is, that wells, as they
exist in most villages, and on many farms in
this country, are an abomination and a per-
petual menace to the health and lives of those
who use them.

130 THE STORY OF THE BACTERIA.

Impure Ice.

The use of ice in preserving food and for
drinking purposes has become a very impor-
tant factor in modern life, and a means of
incalculable benefit to all classes of people.

It was formerly believed that freezing de-
stroyed in large measure the impurities of
water, and within certain limits this is true.
But it has been found, as the result of a long
series of careful experiments by numerous in-
vestigators, that those important contaminating
elements in polluted water, the bacteria, may
resist for long periods the influences of cold.
Good ice is so clear and beautiful that it is
difficult to believe that it may harbor among
its crystals larg-e numbers of even such tiny
bodies as the bacteria, but this is nevertheless
quite true.

It has been found that the ice which is
delivered in New York and in many other
large cities actually contains large numbers of
bacteria.

It has been further found that that most
dreaded form of bacteria, the typhoid bacillus,
may remain for long periods living and viru-
lent in solid ice blocks.

THE STORY OF THE BACTERIA. 131

It follows directly from these simple but
undeniable facts that the sources of our ice
supply should be as carefully scrutinized in the
interests of the public health, as should the
sources of the water. But, unfortunately, under
the influence of the old idea that water was
thoroughly purified by freezing, it has become
the general practice of many of the dealers to
get their ice from almost any source, however
unclean, which is near or accessible enough to
the market to afford a profit.

One of the most flagrant examples of this
bad practice is seen in the ice supply of New
York City, which is in large part drawn from
the sewage-polluted Hudson, and in many
cases from the immediate vicinity of the sewer
openings. Some of the ice which is supplied
to New York is cut on moderately clean ponds
or lakes, but the consumer is almost never
certain that he is not getting Hudson-River
sewer-ice, even when he may fancy he has a
cleaner supply.

The fact is, ice should not be cut, at least
when it is to be used for drinking purposes,
from any source which would not be good if
used for drinking unfrozen. This is certainly

132 THE STORY OF THE BACTERIA,

not the case with any of the Hudson-River
ice, nor with much of that which comes from
other sources.

The criterion of wholesome ice is of course
the same for all regions of the country. The
condition of affairs in New York is cited simply
because it is an example of the extremely ob-
jectionable and dangerous practices which
sensitive and refined people will indulge in
from force of habit or from ignorance of the
nature of their errors.

Many persons who are alive to the dirty and
dangerous character of much of the New-York
ice are looking eagerly either for a reform on
the part of the ice dealers in the character of
the places on which they cut their ice, or to
the establishment of manufactories of artificial
ice, which can be made from water purified by
distillation. It seems at present, however, as
if a spontaneous reform on the part of the ice
harvesters were not to be looked for, and that
this must be brought about either by legisla-
tive enactments or by a determined movement
on the part of a large number of consumers.

The dumping of city garbage in vacant lots

THE STORY OF THE BACTERIA. 133

or in the water in the vicinity of towns is one
of those barbaric practices which strangely
enough still widely prevails in spite of the fact
that both efficient and cheap apparatus for
burning it are well known and employed by
many of the more intelligent and cleanly com-
munities. Thus the soil and the shores of
streams and other bodies of water near towns
are often polluted.

If sewage were everywhere systematically
destroyed, instead of being permitted to run
into and pollute the streams and lakes, which,
from their size and situation, afford the natural
water and ice supplies to towns in their vicin-
ity, the problem, on which so much depends, of
obtaining pure and safe water and ice would
be much easier of solution.

CHAPTER XIII.

THE END OF THE STORY OF THE BACTERIA.

SO important is the subject of the causation
of disease by these minute organisms,
and so full is this field of the promise of
practical and far-reaching benefit to man, that
large numbers of scientific workers all over the
civilized world are eagerly and patiently de-
voting their time and skill to the study of the
disease-producing bacteria.

Great care and technical facility are required
to carry on successfully this kind of investiga-
tion, and it is not at all surprising, since we
have known how to study bacteria for but a
short time, that we should as yet know but
very little about many of the bacterial dis-
eases, or that we should often be mistaken in
our interpretations of what we do know.

There is the greatest temptation for workers
in this field to magnify the importance of

134

THE STORY OF THE BACTERIA. 135

their own observations, or to claim as world-
reforming discoveries the results of imperfect
observation or misinterpreted facts.

The hope of the widespread prevention of
misery and disease, even in the dim dawn of
this new day, is so bright and cheering, and
so full is the air of high-sounding promise of
new and beneficent revelations, that one is
reminded of the description by Lowell of the
advent of a new phase of thought many years
ago in New England. " The nameless eagle,"
he says, " of the tree Ygdrasil was about to sit
at last, and wild-eyed enthusiasts rushed from
all sides, each eager to thrust under the mystic
bird that chalk egg from which the new and
fairer creation was to be hatched in due time."

But in spite of mistakes and misinterpreta-
tions, in spite of the runaway enthusiasms
which now and again lead the disciples of the
new light to ignore the solid groundwork of
experience which was founded in the old, we
are daily gaining new facts and more com-
manding points of view, and the science of
medicine has entered upon a new and brilliant
epoch in its history.

136 THE STORY OF THE BACTERIA.

The mysterious veil which has for so long
hung over some of the most widespread and
terrible of human diseases, is gradually being
drawn aside, and we now stand face to face
with known and understood and no longer, for
the most part, with mysterious and incompre-
hensible foes.

Ten years ago it would have seemed an idle
tale had one said that he could cultivate at will
in the laboratory the very living essence and
causes of such diseases as consumption, typhoid
fever, Asiatic cholera, diphtheria, and more of
the uncanny brood, and could study and ma-
nipulate them as the gardener does his larger
plants, and from the knowledge thus gained
plan new and efficient means for treating and
preventing the diseases which they cause. But
all this is strictly true to-day, as we have seen
in our review of man's invisible foes and the
ravages which they can cause.

And so at last we are at the end of our
story, so far as in such simple and hurried
fashion it can be told to-day. It is a story
which in parts is full of disquieting and un-
pleasant revelations, of facts which at first

THE STORY OF THE BACTEKIA. 137

sight seem to make life under modern condi-
tions less simple and attractive, and Nature, if
we may so personify her, less man's friend.
But after all there are few things more dis-
quieting and unpleasant and unfriendly, to
most people, than are disease and death, and
these, sooner or later, will thrust themselves
into the attention of everybody, be he cognizant
or not of the varied disregard of nature's laws
which for the most part they follow.

It should not be forgotten by those who are
disposed to close their eyes to the disagree-
able and malign influences which, in the guise
of disease-producing bacteria so frequently
surround them, that the rights of others, as well
as their own mental ease, are at stake in this
matter. One has the right, so far as he is
himself concerned, to indulge in almost any
dietetic uncleanliness, or disregard of sanitary
rule with which he may elect to be satisfied ;
but he has no right to expose himself unneces-
sarily to the acquirement of such diseases as
will render him a source of either positive or
possible danger to his fellow men.

Among all th^ myriads of invisible agencies

138 THE STORY OF THE BACTERIA.

which are ceaselessly working for man's weal
we have discovered a few which are his deadly
foes. We have seen that if one looks at the
matter intelligently, the means of largely avoid-
ing the evil effects of these dangerous earth-
neighbors of ours are comparatively simple and
effective, if we do not hide our heads, or shirk,
or waste our time in protestations and regrets.
There are many of the uncanny and dis-
agreeable things of life from which it were
better that most of us turned away our eyes.
But the avoidance of some of those forms of
illness, whose causes have been considered in
this little book, is so closely dependent upon a
general knowledge of their nature that the
offence of unpleasant revelations may, it is
hoped, be forgiven by the reader in view of the
ultimate and universal good which these lines
have been penned to foster.

INDEX.

Abscess . .•

Agar, as culture-medium for bacteria . • • • -34

Air, as source of bacterial infection . • «

Albany, water supply of . .

Amoeba ... . • 4

Asiatic cholera . ;. • 9°, '°!

Bacilli ' . . ' 4°

Bacillus of asiatic cholera . •

" " tuberculosis
" " typhoid fever .

11 prodigiosus . . • .48

Bacteria, action of cold on . . •

li always derived from other bacteria . "
" antagonistic species of .

chemical substances formed by .

11 classification of . • • 39

color-forming . • 46, 47i 4§

'' consumption of, with food
" cultivation of, in agar . ...»

41 " beef-tea

" " " kl gelatin • • -33

" " lk " potatoes . . • 3°

11 development of, in hay infusion

'l disease-producing • • • -53

" forms of . . • • J5

" ik n colonies of ...

" in air .... • 109

"food ... • 103

" kl ice . . • • • • • 45» I3°» * V

" " relation to oxygen ...«••• 44
"water . . ..... "6

" ll wine- and beer-making ...... 43

*l mode of multiplication of • J7

139

140 INDEX.

Bacteria, movements of . «"..-• ." _ . . . 16

" nomenclature of . . . . . . . -39

" occurrence of . •« . . . .22

" of diphtheria . . . . . . . .96

" " measles ...... . 100

" tk pneumonia . . 99

" " scarlet-fever . . 100

" surgical diseases . -59

41 tuberculosis .... .70

" " typhoid fever ........ 84

" " yellow-fever ...... . 101

" phosphorescent ...... .41

" place of, in scale of being . . . . .15

'k pyogenic ......... 68

il rapidity of multiplication of ... 17

" relations to putrefaction . . .20

" role of, in nature ...... .20

11 separation of species by fractional method . . 28

11 kt plate culture . . -35

" size of .... . . 15

" species of, mutually dependent . 50

" spores found in . .19

" staining ... .16

" struggle for existence among . . 18

Bacterial diseases, prevention of . . 79, 86, 104

lk poison, self-propagating . ...... 124

Beef-tea, as culture-medium for bacteria . . . . .29

Berlin, water supply of . 123

Bleeding Host, miracle of . .48

Blood cells ...... ii, 64

Blood poisoning . -59

Bread, color- forming bacteria on .... . . 48

Burning of garbage .... • i32

Carbolic acid . ...... . 81,97,114

Cattle, tubercular .... 73^ Io6

Cells, as bacteria destroyers ... . ,66

" developed from the ovum ... 9

" elementary nature of . . . 2

Childbed fever .'.... .62

Cholera, Asiatica ..... 9°

" bacillus ..... . 91

ik morbus .....•.••• "7

Churches, bacteria in dust of .... . in

Consumption ..... • -7°

INDEX. 141

Corrosive sublimate • » . . . .
Cremation of garbage . • • " • . . -• •

.« 4- • ' 97
. 132

mode of conveyance of germs of, . .
44 spread of, by milk . . . ,
Disease, nature of . . . . , .
44 producing bacteria . " . . ,

' • -97
• ' . .107
• • ~ • • 53

' • • '53

44 as source of infection with tuberculosis .
44 bacteria of wound diseases in . . .

74
61

44 importance of, in ventilation . . .

.109

Erysipelas . . . . . . .

61

Feather dusters . . , . . . .
Fermentation , . . . .
Filters, domestic . . « . .
Filth diseases . f . . ,
Filtration .......

. 113
43
. 125
94
lai, 126

Food, impure, as source of bacterial disease . .
Fowl, tubercular . . . . . •

. 106
. . 106

Furniture in houses ......

. . .114

Garbage, as a source of sanitary danger ...
Gelatin culture-media for bacteria . .
Germs . ... . . .

. 132
33
39

Holmes, Oliver Wendell .....

.63

Ice, artificial ......

44 typhoid bacilli in . . . . .
Inflammation, bacteria of . . . . .

. . 130
. . 64

Leucocytes . . : . . . . .
Living beings, characteristics of . . . •
London, water supply of . . • * •
Lowell, J. R. . . . .'.-..

. ' . . 64
3
• 123
• 135

Malaria . . . « . . .

. . . IO2

Measles .... » . . .

. . . ICO

Micrococcus . . . . . . ,
Milk and diphtheria .....
44 44 scarlet-fever . . . . .

• 3g
. 107

. 107

142 INDEX.

Milk and tuberculosis . •";.«• 73

ik color-forming bacteria in, . . . • . .47

Moon, old plan for communicating with ...... 31

Muscle cells . . . . . . . . . .10

Nerves . . . . . . • "" . • . n

New York, ice supply of .... 130, 131

" Vl water supply of . . . . . . .120

Olynthus\ . . . . . . . . . .6

Overcrowding and disease . ..... 104

Ovum . ....... 9

Pathogenic bacteria ........ 53

Philadelphia, water supply of ....... 122

Phosphorescent bacteria . ..... 41

Physiological division of labor in cells ...... 8

Plate cultures of bacteria ... . . . . . 35

Pneumococcus .... ... 99

Pneumonia and diphtheria . . > • . 100

" bacteria of. . . . . , . .99

Poisons produced by bacteria ... 53, 66, 85

Potatoes for bacterial cultures ....... 30

Predisposition to bacterial disease . . . . 71, 93

Prevention of bacterial diseases . . . . . 79, 86, 104

Protozoa of malaria ..... . 102

Ptomaines . . ... . . „ 53, 66, 85

Pure cultures of bacteria . . . . . . . . 35, 38

Pus . . . . . . . . . . .64

Putrefaction • . "~ . . . . . . .20

Pyogenic bacteria . ....... 68

Rooms, living-, pathogenic bacteria in . . . . . . no

Scarlet-fever . . . . . . . . . . 100

tk " spread of, by milk . . . . . . 107

Sewer gas and diphtheria ........ 99

" " lk typhoid fever ....... 88

Small-pox ... . . . . . 101

Spontaneous generation ... .... 22

Spores, in bacteria ... ..... 19

Sputum, dangers from, in tuberculosis . . • . • 75

Staphylococcus in wound diseases . . . . . .61

Streets, dirty, as source of infection ...... no

Streptococcus . ••••.. 40, 61

of diphtheria . . . . • . .97

Suppuration . .•••••••.64

INDEX. 143

Surgical diseases, bacteria of -59

Theatres, bacteria in dust of . ... . in

Tubercle , 7'

bacillus . ... 7*

Tuberculosis ..... 7°

11 cattle and fowl as sources of infection with . 73, 106

" germ of, in air • .114

41 hereditary predisposition to . • • 71

" infection by, through the air • •' • . 74

" milk, as a source of infection . • • • 73

" modes of preventing spread of .... 79

"• sources of infection with . . • . . .72

Typhoid bacillus, characters of ..... 84

" " in ice . . . . . . • . 89

" " sewer gas . . . • . • .88

" " " water . . . . • . .118

" " mode of entrance to body ..... 85

" poison produced by . . . . • ' . 85

" fever and bacteria ...•••• 84

" " bacteria in food and water . . . 108,118

" " sources of infection . • ' . • . . .86

Ventilation and bacteria . . . . • . • • 109

" of churches and theatres . ., _ • . . . in

" ' lk dwelling-houses . . . . . . .113

Water, bacterial analysis of . . . . % . 35. I24

" bacteria in.. .*•-». - "0

" Croton, of New York .' . • • • . • 120

" filtration of . . . . • . . 121, 125, 126

" from wells . . . . « • ' • . • 127

" sewage polluted . . •» • • . . 87,119,121

lk spontaneous purification of . .. . • . 123

11 supplies of . . . . • . • . . 119

" supply of Albany, N.Y. ..... . 122'

" " Berlin and London ...... 123

" " New York ....... 120

" " Philadelphia . . „ .... 122

u typhoid bacillus in . . . . . . . 87, 118

Wells, as sources of water ..... . 127

White blood-cells 64

Winter cholera . . . . . . . 117

Yellow-fever . . • . • • . . . 101

H £eyt*Boofc for
draining Schools for IRurses.

By P. M. WISE, M.D., President of the New York State
Lunacy Commission ; Medical Superintendent St. Law-
rence State Hospital ; Editor of the State Hospitals
Bulletin ; Professor of Psychiatry, University of Ver-
mont ; Member of the American Medico-Psychological
Association, etc. With an introduction by Dr. EDWARD
COWLES, Physician-in-Chief and Superintendent McLean
Hospital.

Two volumes, 16°, illustrated, sold separately,
each . ' . . . . . . ,/ft?/,$i.25

This work will, it is believed, supply a present reed for training
schools. It is distinctly a text-book for training schools as distin-
guished from a text-book for nurses, and its arrangement provides
tor all the recitations in a two years' course. The first volume is
divided into thirty recitations or chapters, and includes anatomy,
physiology, hygiene (and allied subjects — the atmosphere, ventila-
tion, etc.), the sick-room, infection and disinfection, observation of
symptoms, clinical recording, etc. Its arrangement is based upon a
graded system of teaching ; the first volume being adapted for the
first year's course. The second volume completes the course and
provides for every subject usually taught by recitation in schools for
nurses, leaving no requirement for auxiliary books. In fact the two
volumes furnish completely all the requirements of the training
school for a text-book.

4 ' It is an admirable piece of work. It is written very clearly, and
in language which can be very readily understood by the nurse. It
covers the whole ground, and contains a great deal of matter not to
be found in other books, and with the adoption of this book other
text-books will not be required for the training school." — Dr. G.
ALDER BLUMER, Medical Superintendent of the Utica State Hospital.

"We believe this treatise will be adopted as a text-book in every
training school in the country. Its excellency is such as to justify
this belief, and surely training schools cannot afford to dispense with
the best." — Btiffalo Medical Journal.

G. P. PUTNAM'S SONS, NEW YORK AND LONDON

j^twtets.

A Text=Book for Training Schools for Nurses.

By P. M. WISE, M.D., President of the New York State
Lunacy Commission ; Medical Superintendent St. Law-
rence State Hospital ; Professor of Psychiatry, Univer-
sity of Vermont, etc. With an introduction by Dr.
EDWARD COWLES, Physician-in-Chief and Superintend-
ent McLean Hospital.

Second edition. Two volumes, illustrated, 16°, sold
separately, each $ 1.2 5

" This text-book has been adopted by the ten State Hospitals of
New York, representing approximately four hundred pupils."

Dr. G. ALDER BLUMER (the medical superintendent of the Utica
State Hospital) says: "It is an admirable piece of work. It is
written very clearly, and in language which can be very readily
understood by the nurse. It covers the whole ground, and contains
a great deal of matter not to be found in other books, and with the
adoption of this book other text-books will not be required for the
training school."

A Text-Book of flateria fledica for Nurses.

Compiled by LAVINIA L. DOCK, graduate of Bellevue
Training School for Nurses, late superintendent of
nurses, Illinois Training School for Nurses, etc.

Third edition, revised and enlarged. Thirteenth thou-
sand. 12° . . . . . . . $1-50

** The work is interesting, valuable, and worthy a position in any
library." — N. Y. Medical Record.

"It is written very concisely, and little can be found in it to criti-
cise unfavorably, except the inevitable danger that the student will
imagine after reading it that the whole subject has been mastered.
The subject of therapeutics has been omitted as not a part of a
nurse's study, and this omission is highly to be commended. It will
prove a valuable book for the purpose for which it is intended." —
N. Y. Medical Journal.

An Aid to Hateria fledica.

By ROBERT H. M. DAWBARN, M.D., Professor of Oper-
ative Surgery and Surgical Anatomy, New York Poly-
clinic.

Third edition, revised and enlarged by WOOLSEY
HOPKINS, M.D. 12° . ., . . . $1.25

G. P. PUTNAM'S SONS, NEW YORK AND LONDON

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