BACTERIA IN DAILY LIFE
BY
MRS. PERCY FRANKLAND
FELLOW OF THE ROYAL MICROSCOPICAL SOCIETY; HONORARY MEMBER OF BEDFORD
COLLEGE, UNIVERSITY OF LONDON;
JOINT AUTHOR OF "MICRO-ORGANISMS IN WATER," "THE LIFE OF PASTEUR,"
ETC.
"Spirits, when they please,
Can either sex assume, or both; so soft
And uncompounded is their essence pure,
Not tied or manacled with joint or limb,
Nor founded on the brittle strength of bones,
Like cumbrous flesh; but, in what shape they choose,
Dilated or condensed, bright or obscure,
Can execute their aery purposes,
And works of love or enmity fulfil."
MILTON.
LONGMANS, GREEN, AND CO.
39 PATERNOSTER ROW, LONDON
NEW YORK AND BOMBAY
1903
_All rights reserved_
Transcriber's Note: Minor typographical errors have been corrected
without note. Irregularities and inconsistencies in the text have
been retained as printed. Words printed in italics are noted with
underscores; _italics_. The cover of this ebook was created by the
transcriber and is hereby placed in the public domain.
PREFACE
The title of this little volume sufficiently explains its contents; it
only remains to add that much of the text has already appeared from
time to time in the form of popular articles in various magazines. It
has, however, been carefully revised and considerably added to in
parts where later researches have thrown further light upon the
subjects dealt with.
G. C. FRANKLAND
NORTHFIELD, WORCESTERSHIRE,
_November, 1902_
CONTENTS
PAGE
BACTERIOLOGY IN THE VICTORIAN ERA 1
WHAT WE BREATHE 34
SUNSHINE AND LIFE 65
BACTERIOLOGY AND WATER 93
MILK DANGERS AND REMEDIES 118
BACTERIA AND ICE 149
SOME POISONS AND THEIR PREVENTION 168
BACTERIA IN DAILY LIFE
BACTERIOLOGY IN THE VICTORIAN ERA
A little more than sixty years ago the scientific world received with
almost incredulous astonishment the announcement that "beer yeast
consists of small spherules which have the property of multiplying,
and are therefore a living and not a dead chemical substance, that
they further _appear_ to belong to the vegetable kingdom, and to be in
some manner intimately connected with the process of fermentation."
When Cagniard Latour communicated the above observations on yeast to
the Paris Academy of Sciences on June 12, 1837, the whole scientific
world was taken by storm, so great was the novelty, boldness, and
originality of the conception that these insignificant particles,
hitherto reckoned as of little or no account, should be endowed with
functions of such responsibility and importance as suggested by
Latour.
At the time when Latour sowed the first seeds of this great gospel of
fermentation, started curiously almost simultaneously across the Rhine
by Schwann and Kützing, its greatest subsequent apostle and champion
was but a schoolboy, exhibiting nothing more than a schoolboy's truant
love of play and distaste for lessons. Louis Pasteur was only a lad of
fifteen, buried in a little town in the provinces of France, whose
peace of mind was certainly not disturbed, or likely to be, by rumours
of any scientific discussion, however momentous, carried on in the
great, far-distant metropolis. Yet, some thirty and odd years later,
there was not a country in the whole world where Pasteur's name was
not known and associated with those classical investigations on
fermentation, in the pursuit of which he spent so many years of his
life, and which have proved of such incalculable benefit to the world
of commerce as well as science.
Thanks to Pasteur, we are no longer in doubt as to the nature of yeast
cells; so familiar, in fact, have we become with them, that at the
dawn of the twentieth century we are able to select at will those
particular varieties for which we have a predilection, and employ
those which will produce for us the special flavour we desire in our
wines or in our beers.
Large and splendidly-equipped laboratories exist for the express
purpose of studying all kinds and descriptions of yeasts, for finding
out their characteristic functions, and cultivating them with all the
tenderness and care that a modern gardener bestows upon the rarest
orchids.
All this is now an old story, but some sixty years ago the great
battle had yet to be fought which was to establish once and for all
the dependence of fermentation upon life, and vanquish for ever those
subtle arguments which so long refused to life any participation in
the work of fermentation and other closely allied phenomena.
When, however, Pasteur finally cleared away the débris of
misconception which had so long concealed from view the vital
character of the changes associated with these processes, the
bacterial ball, if we may so call it, was set rolling with a will, and
information concerning these minute particles of living matter was
rapidly gathered up from all directions.
The recognition so long refused to bacteria was now ungrudgingly
given, for it was realised at last that, in the words of M. Duclaux,
"Whenever and wherever there is decomposition of organic matter,
whether it be the case of a weed or an oak, of a worm or a whale, the
work is exclusively performed by infinitely small organisms. They are
the important, almost the only, agents of universal hygiene; they
clear away more quickly than the dogs of Constantinople or the wild
beasts of the desert the remains of all that has had life; they
protect the living against the dead. They do more; if there are still
living beings, if, since the hundreds of centuries the world has been
inhabited, life continues, it is to them we owe it."
Fortunately, the provisions made by Nature for the preservation of the
bacterial race are of so lavish a description that no fear need be
entertained that this useful and indispensable world of life will be
wiped out. The fabulous capacity for multiplication possessed by them
(a new generation arising in considerably less than an hour), the
powers of endurance which some of them exhibit in presence of the most
trying vicissitudes of heat and cold (they have been known to survive
exposure lasting for seven days to a temperature of about -200° C.),
the inability of starvation or desiccation to undermine their
constitution, combine to render the question of the extinction of
bacteria as remote as it is undesirable.
Tempted by the prospects of exploring in this newly-revealed world of
life, investigators rushed into the field, and the bacterial fever has
been hardly less pronounced in these last years than that rush for a
material golden harvest which has characterised so many enterprises in
southern latitudes.
The scientific results of this microbe fever have happily, however,
been of a more solid and substantial character than can be said to
have followed the more tangible but sordid ventures in South African
mines. Vague hypotheses have given place to facts, and bacteria have
been brought more and more within the horizon of human knowledge,
thanks to the genius and untiring zeal of investigators all over the
world.
By mechanical improvements in microscopes, and subtle methods for
colouring bacteria, enabling us to study their form with precision, by
ingenious devices for supplying them with suitable food materials, or,
in other words, by the creation of bacterial nurseries, providing the
means for watching their growth and observing their distinctive habits
and character, this important branch of the vegetable kingdom has been
raised from obscurity to one of the principal places in our catalogue
of sciences, and Bacteriology has won for itself an individual footing
in the scientific curriculum of our great educational institutions,
and is represented in literature by such famous serials devoted to the
publication of bacterial and allied researches as the _Annales de
l'Institut Pasteur_, the _Centralblatt für Bakteriologie_, the
_Zeitschrift für Hygiene_, the _Annali d'Igiene Sperimentale_, and
other well-known journals which constitute an essential but
ever-increasing burden upon the library shelves as well as pocket of
the investigator.
Museums of bacteria have been established where not only specimens of
particular varieties of a permanent character for comparison and
reference can be obtained, but living cultivations of hundreds of
different micro-organisms are maintained; and only those who have had
the charge of bacteria can realise the enormous amount of skilled
labour involved in the catering for such a multitude, in which
individual likes and dislikes in regard to diet and treatment must, if
success is to be secured, be as carefully considered as is necessary
in the case of the most delicate and highly pampered patient.
Bacteria, by means of these depôts, can, in fact, be bought or
exchanged by collectors with as much facility as postage stamps, with
the all-important difference that this collecting of bacteria is not a
mere mania or speculation, but serves a most useful purpose.
To the busy investigator who cannot afford either the time or space in
which to maintain a large bacterial family, it is of immense
convenience to be able to obtain at a moment's notice a trustworthy
culture, say, of typhoid or tuberculosis, or specimens of obscurer
origin from air or water for purposes of investigation. These
bacterial cultures are all guaranteed pure, free from contamination or
admixture with other and alien micro-organisms, and are strictly what
they are represented to be. Although such a declaration is attached to
many commodities at the present day with ludicrous incongruity, in the
case of micro-organisms such a breach of faith is unknown, and the
antecedents of a microbe may be said to be regarded as of as much
moment and to be as jealously preserved as is the pedigree of the most
ambitious candidate for honours at a cattle or dog show!
Amongst some of the curiosities to be found on the shelves of
microbe-museums may be mentioned bacteria which give out light, and
thus, like glowworms, reveal themselves in the dark. These
light-bacteria were originally discovered in sea-water and on the
bodies of sea-fish, and cultures of them have been successfully
photographed, the only source of light being that provided by the
bacilli themselves. The amount of light emitted by a single bacillus
might indeed defy detection by the most sensitive plate procurable,
but when gathered together in multitudes, the magnitude of which even
eight figures fail to express, these phosphorescent bacteria enable
the dial of a watch to be easily read in the dark, whilst photographs
of the face of a watch taken in such bacterial light have been so
successful that the time at which the photograph was taken could be
distinctly seen.
Of bacteria it may indeed truly be said, as has Maeterlinck of the
labours of bees--"though it be here the infinitely little that without
apparent hope adds itself to the infinitely little, though our eye
with its limited vision look and see nothing, their work, halting
neither by day nor by night, will advance with incredible quickness!"
Mention may perhaps appropriately be made here of the highly
interesting fact discovered by Professor Percy Frankland, that
ordinary bacteria which do not phosphoresce are capable of affecting a
photographic film in absolute darkness, and can by this means produce
a picture of themselves. If, however, a transparent piece of glass is
placed between the bacteria and the film no photograph results,
showing that glass interferes with their activity in this respect. The
author points out that as this action upon the photographic film does
not take place through glass, it is in all probability due to the
evolution by the bacteria of certain volatile chemical substances
which either directly or indirectly enter into reaction with the
sensitive film. Similar phenomena have been discovered in regard to
many metals as well as organic substances, but this is the first
observation which has been recorded of the action of living structures
on sensitive films in the dark.
We have already referred to the important services which Pasteur has
rendered by distinguishing between different varieties of yeast, and
separating them out according to their functions and properties--pioneer
work which has been followed up by and borne such splendid fruit in
the hands of the renowned Danish investigator, Emil Christian Hansen
of Copenhagen. This work of isolating out individual varieties of
micro-organisms has been not only pursued with the energy familiar to
all in the case of bacteria associated with disease, but has been
pursued in various other, though perhaps less well known, directions.
A great deal of activity has lately been exhibited in so-called dairy
bacteriology, and a long list has already been compiled of milk,
cheese, and butter microbes; and agricultural authorities, even in
this country, are slowly awakening to the fact that, in order to
compete on modern lines with foreign dairy produce, dairy schools must
be established, where bacteriology is taught, and where instruction is
given in the principles of scientific butter and cheese making.
But bacteria of the brewery and of the dairy are not the only useful
germs which are to be found on the shelves of microbe museums. Wine
and tobacco manufacturers on application may respectively obtain the
bacterial means of transforming the crudest must into the costliest
claret, and the coarsest tobacco into the most fragrant Havana.
Already considerable progress has been made in the isolation of
particular varieties of wine-yeast, whilst highly encouraging results
have been obtained by Suchsland and others in the separation of
various valuable tobacco-fermenting organisms. Agricultural
authorities, again, owe a debt of gratitude to those distinguished
investigators whose labours have discovered the art of imprisoning the
micro-organisms which play such an important part in the fertilisation
of the soil. Bacterial fertilisers are amongst the latest achievements
which bacteriology has accomplished in this wonderful half-century,
and the purchase of special varieties of bacteria to suit the
requirements of particular kinds of leguminous plants is now fast
becoming a mere everyday commercial transaction. But efforts for the
amelioration of the conditions under which plant life is carried on
have not been confined to providing plants with suitable bacterial
friends; vigorous and successful efforts have been made to remove from
their _entourage_ those bacterial enemies and undesirable parasites
which have for so long played so important a part in the crop-returns
of many an agriculturist.
For the identification and separation of the plant-parasites of
various kinds we have largely to acknowledge our indebtedness to
American investigators, and the encouragement and support which Dr.
Erwin Smith, amongst others, has received from the Government of the
United States in the prosecution of these researches indicates how
great is the public importance attached to them. There are in America
alone fifty experiment stations where plant diseases are studied,
whilst at a number of the colleges and universities more or less
attention is given to the subject. Some idea of the loss occasioned to
agriculturists by these plant pests may be formed by a recent
announcement that the Department of Agriculture in Queensland was
prepared to offer a reward of £5,000 for the discovery of a means to
eradicate the prickly-pear disease. Plant pathology has not yet had a
distinct chair allotted to it in any of the great universities, but
the subject is of such vast industrial importance, that doubtless
before long some seat of learning will do itself the honour to
establish one, and so set the example.
A striking instance of the advantages of taking stock, so to speak, of
the attributes of bacteria will occur to everyone in the revelation
which has followed of their powers to solve one of the most knotty
problems of the day--the efficient manipulation of those vast
subterranean rivers of sewage which honeycomb every city of the world.
The purification which sewage underwent by passing it through the
pores of the soil, or, in other words, by filtration, was recognised
about the year 1870, soon after the Rivers Pollution Commissioners had
begun to make their classical investigations on the land treatment of
sewage; but although the rapid transformation of ammonia into nitrates
which followed the passage of the sewage through a few feet of soil
was noted, yet the mechanism of this nitrification process remained a
mystery until 1877, when two French chemists--MM. Schloesing and
Muentz--made the then astounding discovery that this change was
dependent upon the vital energies of micro-organisms.
The part played by bacteria in the purification of sewage thus became
an established fact, and the later experiments have been devoted to
studying the necessary conditions under which the maximum amount of
work is obtainable from these novel bacterial labourers.
Two different classes of bacteria are required to carry on the
purification of sewage: those which flourish in the _absence_ of air
and are known as anaërobic bacteria, and those to which the _presence_
of air is essential for the exercise of their functions, the latter
being therefore called aërobic bacteria.
The work of the anaërobic labourers consists in breaking down the
complex organic compounds present in sewage, whilst the completion of
the process of purification is left to the aërobic varieties. In the
ordinary course of nature both these processes are going on side by
side, but it has been found advisable to separate these two different
classes of bacteria as far as possible, and allot distinct premises to
the anaërobic and aërobic varieties respectively engaged in the
purification of sewage, for by so doing experience has shown that the
work is not only more expeditiously, but also more efficiently,
carried out.
Now the anaërobic bacteria are supplied along with the sewage, and the
retention of their services offers practically no difficulty as long
as an ample allowance of space and time is given them in which to
carry on their labours. The aërobic bacteria, however, besides
demanding space and time, insist upon their workshops being well
ventilated, and if the supply of fresh air is in any way curtailed
they stop work entirely. Hence the ventilation of the aërobic
workshops becomes a matter of primary importance if the valuable
services of these labourers are to be retained. To ensure a sufficient
supply of air being provided, it has been found advisable to have two
or more aërobic workshops or bacteria contact beds, and the sewage is
passed from one on to a second, and so on, until the purification is
complete. Under proper management the sewage should leave the works as
an inodorous, almost pellucid liquid, incapable of putrefaction, which
may be turned into rivers or other waterways without fear of rousing
the wrath of local riparian authorities.
But whilst the commercial side of bacteriology, so to speak, has made
such great strides, the purely scientific applications which have been
made of the facts it has furnished have by no means lagged behind.
Chemists, from Pasteur downwards, have made use repeatedly of special
bacteria to perform delicate operations in the laboratory which other
methods have either failed to accomplish or have performed in a clumsy
and less expeditious manner.
There can be no doubt that, as our knowledge grows from day to day, we
shall find more and more how much depends upon the work of individual
bacteria, and how much importance attaches to the selection of just
those varieties which are of value, and the banishment of those which
are detrimental; and thus the many applications which bacteria already
admit of render their easy access a matter of increasing consequence,
enhancing the value of bacterial institutions such as already exist on
the Continent.
But whilst the easy access of bacteria for experimental and scientific
purposes is of great importance to the investigator, their
indiscriminate distribution would equally be a source of uneasiness
and danger to the community at large. Already sensational fiction has
made considerable capital out of the pathogenic microbe, and with the
winged aid of penny publications it does not take long for suggestions
of such kinds to spread in society and assume practical shape, and
whilst the administration of bacterial poisons offers comparatively
but little difficulty, their identification would be a far greater
problem for experts than that presented by particular chemical
poisons. To cope with this danger to the public, specimens of
disease-germs from these bacterial depôts may not be supplied to
applicants unless the latter can prove to the satisfaction of the
director that they are connected with responsible public institutions.
In recent times, indeed, one of the most remarkable practical uses to
which bacteria have been put is that of poisoning-agents on a large
scale, or in other words vermin exterminators; if this new rôle for
bacteria becomes extended, as no doubt it will, the law for the sale
of noxious drugs and preparations will also doubtless be amended to
cover the distribution of bacterial-poisons.
It was in the year 1889 that Professor Loeffler, while experimenting
with mice in his laboratory at Greifswald, discovered a micro-organism
which was extremely fatal to all kinds of mice. The happy idea
occurred to the Professor that this lethal little microbe, which he
christened _Bacillus typhi murium_, might be turned to excellent
account in combating plagues of field mice in grain-fields, where the
devastation committed by these voracious rodents had become in parts
of Greece and Russia a serious source of loss to agriculturists.
Experiments were accordingly made on a small scale to test the
efficiency of this bacterial poisoner in destroying field mice, and so
successful were the results that Loeffler confidently announced the
possibility of keeping down these pests by distributing food material
infected with these bacteria over fields which were invaded by them.
The Greek Government took up the question, and Loeffler's method was
applied with brilliant results; the disease was disseminated with
extraordinary rapidity and severity, and the mice were readily
destroyed.
It is highly satisfactory to find that the character of this
mouse-bacillus has stood the test of time, for after a period of more
than ten years most encouraging reports concerning its efficiency
still continue to be received. In one of the latest of these, drawn up
by the Director of the Experimental Agricultural Institute in Vienna,
we read that in no less than seventy per cent. of the cases in which
it was employed it was completely successful in its work of
extermination, and it is interesting to note that in a considerable
number of these instances it was the domestic mouse against which its
energies were directed. The rat has, however, until recently escaped
the hand of the bacterial executioner, but his knell has also now been
sounded in the announcement that a rat-bacillus has been discovered.
Considering the undesirable notoriety which these rodents have of late
obtained in connection with their undoubted culpability in the
dissemination of plague, this discovery, if correct, should be warmly
welcomed. That there is plenty of work awaiting such a micro-organism
may be gathered from the fact that during the outbreak of plague in
Sydney the crusade against rats which followed led to the slaughter in
one year of over 100,000.
The discoverer of this useful member of the microbial community is
Tssatschenko, of the University of St. Petersburg, and in his memoir
he states that, whilst highly virulent as regards rats, it is quite
harmless to domestic animals of various kinds. Thus cats, dogs, fowls,
and pigeons when fed with food infected with the bacillus suffered no
ill effects whatever, whilst its administration in large quantities to
farm stock, such as horses, oxen, pigs, sheep, geese, and ducks, was
also without result; hence its distribution, according to its
discoverer, offers no danger to other animals.
This idea of employing bacteria as executioners was not original, for
Pasteur had already in 1888 suggested to the Intercolonial Rabbit
Commission in Australia that chicken-cholera microbes should be
employed for destroying the rabbits, which then, as now, are such a
source of difficulty and pecuniary loss to the country. No active
measures appear to have been taken, however, to carry out this
suggestion, one of the principal objections raised being the
undesirability of introducing a disease which was at that time
believed to be a stranger to the colony. Recently the idea has been
revived by Mr. Pound, the Government bacteriologist at Brisbane, in
consequence of his discovery that chicken-cholera, far from not
existing in Australia, has infested poultry yards more or less
extensively for several years past, although it has only lately been
accurately diagnosed as such. This chicken-cholera microbe is
particularly well suited for the work in question, inasmuch as, whilst
extremely fatal to rabbits, it produces, like Loeffler's bacillus, no
ill effect whatever on farm-stock of various kinds, and is perfectly
harmless to man, so that its handling by the uninitiated is not
attended with any personal danger.
This brings us to what may be designated the human side of
bacteriology, _i.e._ its relation to disease and its prevention. In
these important departments of life the services already rendered by
this infant prodigy of science can as yet be only approximately
appreciated. Anthrax, tuberculosis, cholera, typhoid, plague,
influenza, tetanus, erysipelas, are only a few of the diseases the
active agents of which bacteriology has revealed to us. Bacteriology
has, however, not been content to merely identify particular
micro-organisms with particular diseases, it has striven to devise
means by which such diseases may be mastered, and one of the most
glorious achievements of the past sixty years is the progress which
has been made in the domain of preventive medicine.
The classical investigations of Pasteur on the attenuation of
bacterial viruses such as those of chicken-cholera and anthrax, and
his elaboration of a method of vaccination with these weakened viruses
whereby the power of the disease over its victim is removed or
modified, are too well known to require repetition here. The success
which followed Pasteur's researches in this direction led him to
undertake that great and difficult task, the prevention of rabies in
the human subject--a task well-nigh superhuman in its demands, and one
which only he could accomplish in whose life the pregnant words of a
modern writer found expression--"il ne suffit pas de posséder une
vérité, il faut que la vérité nous possède." The victory over this
disease, which crowned a long life replete with brilliant
achievements, has been universally recognised, and numerous institutes
have arisen in all quarters of the globe for extending the benefits of
this discovery for the relief of suffering humanity. These Pasteur or
bacteriological institutes also furnish highly important centres where
original research work of various kinds is carried on, and the
stimulus which has thus been given to experimental science in the
remotest parts of the world cannot be overestimated.
Methods for the prevention of disease have, however, not been confined
to the elaboration and employment of modified or weakened bacterial
viruses; the subject has been still more recently approached from
another and quite different side. This new departure we also
originally owe to France, although its practical development has been
worked out in Germany.
It was in 1888 that two Frenchmen, Richet and Héricourt, communicated
a memoir to the _Comptes rendus_ of the Academy of Sciences,
describing the curious results they had obtained with rabbits
purposely infected with a disease microbe, the _Staphylococcus
pyosepticus_. Some of the rabbits died after being inoculated with
this micro-organism and some remained alive, and they proceed to point
out how it was that such different results were obtained. Before the
inoculations were made some of the animals received injections of
blood taken from a dog, which a few months previously had been
infected with this same microbe, but had recovered. The rabbits which
received the dog's blood all survived the inoculations, whilst those
which did not, succumbed in every case to the action of the
_Staphylococcus pyosepticus_. So struck were the authors by these
remarkable results that they repeated them, and their further
investigations fully confirmed those originally obtained, proving that
they were not "un fait exceptionnel."
Here we have the first steps in the direction of serum-therapy, that
new treatment of disease which during the last few years has been so
prominently before the public in the cure of diphtheria, tetanus, and
other maladies, and for the development of which we owe so much to the
labours of Behring, Roux, Kitasato, and other investigators.
The astounding fact that the blood of animals which have been trained
to artificially withstand a particular disease becomes endowed with
the power of protecting other animals from that disease is only in the
earliest stages of its application. The results, however, which have
already been accomplished are of so encouraging a character that the
hope is justified that serum-therapy is destined to revolutionise the
treatment of disease. One of the latest uses which has been made of
this method of combating disease is the employment of serum for the
cure of bubonic plague. During the recent outbreak of plague in India,
Yersin, formerly a student and assistant at the Paris Pasteur
Institute, was despatched to India to superintend the administration
of this new remedy, and the serum he employed was that derived from
horses which had been subjected to, and had recovered from,
inoculations with the plague bacillus. The treatment of snake bites by
means of curative serum will be dealt with in more detail later on; it
only remains to cite it here as another instance of the success which
is attending the new methods of protection against disease.
Another and highly ingenious application of serum has been brought
forward by Pfeiffer, Gruber, Widal, and others. This is the so-called
sero-diagnosis of disease, and has been employed already with success
in the identification of typhoid fever as such. The method sounds
simple in the extreme, and consists in taking a few drops of blood
from a patient supposed to be suffering from typhoid fever and mixing
them with a recent cultivation in broth of genuine typhoid bacilli. If
the blood is derived from a typhoid-infected person, then the bacilli
should exhibit a curious and characteristic appearance when examined
under the microscope. Instead of moving about as individuals in
various parts of the microscopic field, they should be seen gathering
or clumping together in numerous small heaps, their movements the
while becoming paralysed.
The State Board of Health of Massachusetts has recently taken up the
official sero-diagnosis of typhoid fever, and issues in response to
applications a simple outfit with instructions how to collect
specimens of blood and a form which they request shall be returned
filled in with all the details concerning the case under observation.
Only a few drops of blood are required for the examination, and these
before being despatched to the State Laboratory are collected on slips
of paper and allowed to dry. If the addition of this suspected blood
in the proportion of one to twenty to a young and vigorous culture of
typhoid bacilli succeeds in paralysing their movements, producing the
characteristic clumping together or agglutination of the bacilli, then
the reaction is considered positive and the case one of typhoid fever.
That, however, some risk attends the placing of too implicit a
reliance on this method of diagnosis alone is evident from the fact
that a _negative_ reaction, or in other words, absence of all
agglutinising phenomena, is sometimes associated with blood throughout
what is beyond all question a well-defined case of typhoid fever,
whilst in the first week of this disease the test is frequently
negative in character. Rouget, who has made a very careful inquiry
into the value to be attached to the sero-diagnosis of typhoid fever,
states that he has found in a large number of examinations of blood
derived from undoubted typhoid patients the agglutination phenomena
fail altogether; it is, therefore, not surprising that the
sero-diagnosis of this disease is still the subject of much discussion
and investigation.
An interesting example of how particular serums may be employed for
the detection of particular poisons has been furnished by Dr.
Calmette. In some districts of India the natives have an ugly custom
of wreaking their vengeance on their enemies by poisoning their
cattle, and to effect this both expeditiously and secretly they employ
subtle poisons which they know can only be detected with great
difficulty. Serpent venom is a favourite substance, whilst abrine, a
highly toxic vegetable poison, is another. The method adopted for the
application of this abrine is highly original, and consists in taking
small bits of wood shaped like miniature clubs, so diminutive in size
that they can be concealed in the hand. In the head of the club small
holes are bored, and tiny pointed rodlets of a hard greyish substance
are fitted into them. Armed with these crude instruments, the natives
scratch the cattle in several places, and, although but little
external sign of injury is to be seen, the rod-points penetrate the
skin and are broken off, and the poison is left to work its lethal way
through the animals' system. Mr. Hankin forwarded some of these
broken-off rod-points to Dr. Calmette for the identification of their
composition, and he diagnosed the material employed as abrine in the
following original manner. He first introduced some of this rod
material into animals, and found that their symptoms were suggestive
of abrine poisoning. To confirm his suspicions, however, he took some
more of this rod material, and, before inoculating it into animals, he
mixed it with serum derived from animals which had been artificially
rendered immune to abrine poison. Instead of the animals into which
this mixture of serum and "rod material" had been introduced dying
like the previous ones, they remained alive. Had the "rod material"
consisted of some poison other than abrine, the abrine serum would
not, according to Dr. Calmette, have negatived its action, and it has
thus been indicated how protective serums may be successfully employed
for the detection of poisons.
Foremost, however, among the beneficent reforms which have followed in
the wake of bacteriology must be placed the antiseptic treatment of
wounds, or Listerism, as it is now universally designated in
recognition of its renowned champion, the former President of the
Royal Society. "Lister comprend," in the words of Dr. Roux, "que les
complications des plaies sont dues aux germes microbiens venus du
dehors et il imagine les pansements antiseptiques. Avec l'antiseptie
commencent les temps nouveaux de la chirurgie." It only remains to add
that, with the modesty characteristic of a great man, its brilliant
author delights in repeating how any good which he may have been
permitted to do he owes entirely to the inspiration which he received
from the labours of Louis Pasteur.
But if the Victorian era has been productive of so many important
applications of bacteriology to commerce and medicine, this period has
been also fraught with results of the highest moment in the progress
of hygiene.
The terms of intimacy, so to speak, which we have been now able to
establish with bacteria has enabled us to discover details of their
life and habits which before were shrouded in mystery. Their
distribution in air has led to renewed endeavours on the part of
sanitary authorities to procure efficient ventilation in our hospitals
and public institutions; dust has acquired a fresh horror since it has
been shown how disease germs may be disseminated by its means; whilst
the important part which flies and lice may play in the spread of
epidemics has opened up a new field for research, and made us
conscious of a fresh source of danger in our daily life.
The general public, however, is hardly yet fully alive to the capacity
for mischief possessed and exercised by the common house-fly. True, it
is universally execrated and regarded as a tiresome attendant upon the
summer months, but it is not usually considered in any more serious
light. That however, the comparative indulgence with which this homely
insect pest has been treated is decidedly misplaced and fraught with
danger to health, the researches of numerous scientists have now
conclusively proved.
As long ago as the year 1888 Professor Celli showed that the germs of
consumption, anthrax, and typhoid fever could pass through the
digestive organs of flies and reappear in the excreta of the latter
not only alive but in full possession of their disease-producing
powers. Dr. Sawtschenko made similar experiments with cholera germs.
Healthy flies were placed under glass shades and fed with broth in
which these micro-organisms were growing, and the latter were not only
subsequently recovered from the digestive organs of the flies but also
from their excreta in a living and virulent condition.
This is, however, not the only means whereby these insects can
distribute deadly and other microbes, for it has been shown that in
crawling over substances containing bacteria these may become attached
to the feet of flies, and are in this manner transferred to other
materials upon which they may alight, just as Pasteur showed many
years earlier silkworms can communicate the fatal plague of pébrine by
crawling over each other's bodies, carrying in their disease-laden
feet the infection from one worm to another. During the recent
outbreak of bubonic plague in the East the part played by flies in
disseminating the virus has been repeatedly emphasised. Yersin was the
first who called attention to the presence in large numbers of
virulent plague bacilli within the bodies of flies which he collected
in the vicinity of plague-stricken persons, and it was found that
flies which had fed on plague-infected material and were then isolated
lived for several days afterwards, during which time virulent plague
bacilli were present in their bodies in immense numbers; thus were
these insects converted into winged messengers of evil of the most
repulsive type.
I am not aware whether any experiments on the vitality and
transmissibility of diphtheria and consumption germs by means of flies
have been made; but in view of the overwhelming evidence of the
culpability of these insects in spreading plague, it is not
unreasonable to presume a responsibility on their behalf in regard to
other diseases; indeed, in the report issued by the Army Medical
Commissioners of the Spanish-American War, it is emphatically stated
that flies played an important part in the dissemination of typhoid
fever.
There is no question as to the capability of certain micro-organisms
to reside for considerable periods of time within the bodies of flies,
and during this sojourn to abate no jot of their virulence. Indeed, it
has been shown that the bodies of these insects may constitute
incubators of a most successful type, for some varieties of bacteria
grow luxuriantly and multiply abundantly within them.
In the hot days of summer, when flies abound, it would be well to
banish these insects, as far as lies in our power, not only from our
sick-rooms in particular, but from our general surroundings. The
catholic taste of flies for garbage of all kinds is too well known to
require entering into, but the consequences which may follow from
their visits to dustbins and centres of disease, and then alighting
upon our food or persons, has received too little attention in the
past.
In regard to the subject of insects as disease disseminators, it may
be mentioned that Mr. Hankin, when studying plague conditions in
India, expressed his belief that ants in Bombay also assisted in
spreading the scourge, for he found that when he inoculated mice with
the excreta of ants, such insects having previously fed on
plague-stricken rats, the mice succumbed to plague in a few hours.
Fleas have also been conclusively proved to be carriers of plague
germs.
There is no doubt that the revelations of hygienic science have
aroused the vigilance and zeal of public authorities in various new
directions to try and cope with the spread of zymotic disease.
In no direction, perhaps, is the fruit of this energy so apparent as
in the increasing supervision which it has incited over two of the
greatest menaces to public health which hang over society--_i.e._ our
water and dairy supplies. Now that it has been proven beyond doubt
that the germs of consumption, typhoid fever, and cholera can be and
are distributed through the consumption of contaminated milk or water,
not to mention other diseases such as diphtheria and scarlet fever, an
ever-increasing demand is being made that these all-important articles
of diet shall be protected from pollution, and that public authorities
shall be made responsible for their distribution in a pure and
wholesome condition.
It is, however, undoubtedly in the matter of water that the greatest
service has been rendered by bacteriology to sanitary science, and for
the important advance in this department we are indebted to the
beautifully simple and ingenious methods devised by Robert Koch.
Not yet twenty years have passed since the new bacterial examination
of water was introduced and systematically employed, and the use which
has been made of the opportunities thus opened up of investigating
water problems on an entirely new basis is shown by the voluminous
dimensions which the literature on this one branch of bacteriology
alone has reached. Considerably upwards of two hundred different water
bacteria have been isolated, studied, and their distinctive characters
chronicled. The behaviour of typhoid, cholera, and other
disease-producing microbes in waters of various kinds has been made
the subject of exhaustive experiments; the purification power of
time-honoured processes in operation at waterworks and elsewhere has
been for the first time accurately estimated. Water engineers have
through these bacteriological researches been provided with a code of
conduct drawn up by the light of erudite scientific inquiries, which
has now rendered possible the removal of the process of water
purification from the rule of empiricism guided by tradition, and to
raise it to the level of an intelligent and scientific undertaking.
The above short sketch may serve to convey some idea of the rise and
phenomenal development of bacteriology during the past sixty years. To
record, even in outline, the individual triumphs of the various
branches of this science would require volumes, whilst the astounding
mass of work already accumulated by its devotees is but the earnest,
the guarantee of yet greater achievements in the future.
The progress which has been made in this brief period of time must not
necessarily be expected to continue at this rapid rate; it may be that
generations to come have yet the hardest and the longest tasks to
accomplish; for in science, as in other walks of life, it is, as a
rule, the easiest problems, which are first disposed of, and the
farther we advance the more complicated, the more intricate become the
questions to be attacked, the difficulties to be overcome.
The late Queen's reign has bestowed a splendid legacy of
bacteriological discoveries upon those who, in the future as in the
present, must inevitably follow in the footsteps of those great and
brilliant leaders of bacteriological science belonging to this
auspicious era, Louis Pasteur and Robert Koch.
WHAT WE BREATHE
Few people realise that, with the advent of autumn, the great majority
of the swarms of bacteria which have been circulating in the air
during the hot summer months take their leave of us and disappear.
Practically, however, we are all conscious of this fact, for we know
what greater difficulties attend the keeping of food sweet and
wholesome in the summer than are met with in the winter; bacteria, not
unlike some other armies of occupation, securing a footing rather by
their numbers at this season of the year, than by virtue of the
superior strategy or, in other words, special attributes of their
units. Bacterial operations are, however, distinctly favoured by the
accident of temperature, the warmth of the summer encouraging their
vitality and multiplication.
When Pasteur first announced his conviction that the familiar
phenomena of putrefaction and decay were due to minute living
particles present in our surroundings, his sceptical critics sought to
ridicule his conclusions by declaring that, were this the case, the
air must of necessity be so heavily laden with living forms that we
should be surrounded by a thick fog--"dense comme du fer." We do not
now, forty years later, require to recite the exquisitely simple
experiments which, whilst sufficiently establishing his theories,
served to effectually suppress those of his opponents.
Since Pasteur's pioneering work was carried out, a vast number of
investigations have been made in all parts of the world by scientists
of almost every nationality on the subject of the distribution of
bacteria in air, and not only on their distribution, but on their
functions or the place they occupy in the economy of nature. With our
increased knowledge concerning their distribution has come our ability
to differentiate between individuals, and to adequately assess the
value and importance of their work from various points of view.
In the bacterial treatment of sewage we have not only one of the
latest, but perhaps also one of the most successful examples of that
system of division of labour, or specialisation of energy, which forms
such a characteristic feature of work of all kinds at the present
time. Other familiar instances of the applications of individual and
special bacterial labourers to the solution of industrial problems are
to be found in the conduct of commercial undertakings of such national
magnitude and importance as brewing and agriculture. But it is not
with these beneficent or great industrial classes of bacteria that we
are now more immediately concerned, but rather with the malevolent
varieties, or the so-called "submerged tenth," for which no labour
colony has at present been created to direct their energies into
useful and profitable channels.
We know that as regards mere numbers the bacteria in air may vary from
0 to millions in a couple of gallons, these extremes being dependent
upon the surrounding conditions or relative purity of the atmosphere.