By Prof. SAMUEL BELL, M.D.
Physiology has for many decades been a science founded on experiment,
and pathology has been rapidly pressing forward in the same direction.
To read the accounts of how certain conclusions have been arrived at
in the laboratory, by ingenious devices and by skillful manipulations,
is as fascinating as any tale of adventure.
When the microscope began its work, how discouraging was the vastness
and complexity of the discoveries which it brought to light; how many
years has it been diligently used, and how uncertain are we still
about many of its revelations! But what a happy conjecture of man, and
as proper environment takes place we may reach better results! Let me
give an illustration:
Some thirty years ago, Virchow began his studies and lectures upon
cellular pathology. The enthusiasm which he awakened spread over the
whole medical world. The wonderful attention to detail, the broad
philosophy which signalized his observations, were alike remarkable.
His class room was packed with students from every country, who
thought it no hardship to struggle for a seat at eight o'clock in the
morning. With his blackboard behind him and specimens of pathology
before him, and microscopes coursing upon railway tracks around the
tables which filled the room, he was the embodiment of the teacher;
his highest honor was as discoverer. The life and importance of the
cell, both in health and disease, it has been his work to discover and
to teach. The point of view from which he has classified tumors is
founded on this basis, and remains the accepted method. The light
which he cast upon the nature of inflammation has not yet been
obscured, and while other phenomena appear, the multiplication of
cells and nuclei and the formation of connective tissue in the process
of inflammation will always call to mind his labors.
To one of Virchow's pupils, Prof. Recklinghausen, we chiefly owe our
knowledge of the phenomena of diapedesis as a part of the inflammatory
activity. How incredible it seems that masses of living matter can
make their way through the walls of blood vessels which do not rupture
and which have no visible apertures!
Virchow fixed his attention upon the forms and activities of the
cells, their multiplication and degradation, and how they build up
tissues, both healthy and morbid.
To another matter with which, both literally and metaphorically, the
air is filled, we must also make allusion. The existence of
micro-organisms in countless numbers is no new fact, but the influence
they may exert over living tissues has only lately become the subject
of earnest attention. So long as they were not known to have any
practical bearing upon human welfare, they interested almost nobody,
but when, however, it was shown that putrefaction of meat is due to
the agency of the _bacterium termo_, and the decomposition of albumen
to the _bacillus subtilis_; when anthrax in cattle and sheep was found
to depend on the _bacillus anthracis_, and that in human beings it
caused malignant pustules; when suppuration of wounds was found to be
associated with micrococci; and when it was announced that by a
process of inoculation cattle could be protected against anthrax, and
that by carbolic spray and other well known precautions the
suppuration of wounds could be prevented--all the world lent its ears
and investigation at once began.
Because labors in bacteriology promised to be fruitful in practical
results, the workers speedily became innumerable, and we are
accumulating a wondrous store of facts. How long now is the list of
diseases in which germs make their appearance--in pneumonia, in
endocarditis, in erysipelas, in pyæmia, in tuberculosis, and so on and
so on. One of the most striking illustrations is the gonococcus of
gonorrhoea, whose presence in and around gives to the pus cells
their virulent properties, and when transferred to the eye works such
lamentable mischief. Without their existence the inoculation of pus in
the healthy eye is harmless; pus bearing the gonococci excites the
most intense inflammation. Similar suppurative action in the cornea is
often caused by infection of cocci. The proof of causation may be
found in the fact that the most effective cure now practiced for such
suppuration is to sterilize them by the actual cautery. Rosenbach says
that he knows six distinct microbes which are capable of exciting
suppuration in man. Their activity may be productive of a poison, or
putrefactive alkaloid, which is absorbed.
There are at present two prominent theories in regard to the
infections which produce disease. The first is based upon chemical
processes, the second upon the multiplication of living organisms. The
chemical theory maintains that after the infectious element has been
received into the body it acts as a ferment, and gives rise to certain
morbid processes, upon the principle of catalysis. The theory of
organisms, or the germ theory, maintains that the infectious elements
are living organisms, which, being received into the system, are
reproduced indefinitely, and excite morbid processes which are
characteristic of certain types of disease. This latter theory so
readily explains many of the facts connected with the development and
reproduction of infectious diseases, that it has been unqualifiedly
adopted by a large number of investigators. The proofs of this theory
had not, however, advanced beyond the demonstrations of the presence
of certain forms of bacteria in the pathological changes of a very
limited number of infectious diseases, until February, 1882, when Koch
announced his discovery of the tubercle bacillus, since which time
nearly every disease has its supposed microbe, and the race is,
indeed, swift in which the would-be discoverers press forward with new
germs for public favor.
The term bacteria or microbe refers to particles of matter,
microscopic in size, which belong to the vegetable kingdom, where they
are known as fungi. If we examine a drop of stagnant water under the
microscope, amplifying say four hundred diameters, we see it loaded
with minute bodies, some mere points, others slightly elongated into
rods, all actively in motion and in various positions, a countless
confusion. If evaporation now takes place, all is still. If we now
apply moisture, the dried-up granules will show activity, as though
they had not been disturbed.
All these different organisms have become familiar to us under the
generic term bacteria, which is a very unfortunate application, as it
really applies to only a single class of fungi. Cohn calls them
schizomycetes, and makes the following classifications:
1. _Sphero-bacteria_, or microbes.
2. _Micro-bacteria_, or bacteria.
3. _Desmo-bacteria_, or bacilli.
4. _Spiroteria_, or spirillæ.
The _spiro-bacteria_, or micrococci, are the simplest of the fungi,
and appear as minute organisms of spherical form. They multiply by
fission, a single coccus forming two, these two producing four, and so
on. They present a variety of appearances under the microscope. From
single isolated specimens (which under the highest magnifying power
present nothing beyond minute points) you will observe them in pairs,
again in fours, or in clusters of hundreds (forming zoöglea) and still
adhering together, forming chains. When a given specimen is about to
divide, it is seen to elongate slightly, then a constriction is
formed, which deepens until complete fission ensues.
Micrococci possess no visible structure. They consist of a minute
droplet of protoplasm (mycroprotein) surrounded by a delicate cell
membrane. Certain forms are embedded in a capsule (diameter 0.0008 to
0.0001 millimeter).
These little organisms, when observed in a fluid like blood, sputum,
etc., are found to present very active movements, although provided
with no organs of locomotion.
This Brownian motion is possessed by almost every minute particle of
matter, organic and inorganic, and is not due to any inherent power of
the individual. They are almost omnipresent, abounding in the air, the
earth, the water, are always found in millions where moist organic
matter is undergoing decomposition, and are associated with the
processes of fermentation--in fact, they are essential to it. The
souring of milk succeeds the multiplication of these germs. Certain
varieties are pigmented, and we observe colonies of chromogenic cocci
multiplying upon slices of boiled potato, eggs, etc., presenting all
the colors of the rainbow. All of these germs are not the cause of
disease. Certain species, however (termed pathogenic), are always
associated with certain diseased conditions.
The _bacteria-termo_--micro-bacteria--are slightly elongated, and
inasmuch as they multiply by division, frequently appear coupled
together, linked in pairs, and in chains. They are generally found in
putrefying liquids, especially infusions of vegetable matter. They
possess mobility to a remarkable degree. Observing a field of
bacteria-termo under the microscope, they may be seen actively engaged
in twining and twisting. A flagellum has been demonstrated as attached
to one or both extremities. This is too minute to be generally
resolved, even if it is a common appendage.
_Desmo-bacteria_ (or bacilli) are rod-like organisms, occurring of
various lengths and different thicknesses. In a slide of the bacillus
of tuberculosis and anthrax, we notice at intervals dots which
represent the spores from which, as the rods break up, future bacilli
are developed.
Then we have _spiro-bacteria,_ the spirilla and the spirochetæ; the
former having short open spirals, the latter long and closely wound
spirals. The _spirillum, volutans_ is often found in drinking water,
and in common with some other specimens of this class is provided with
flagellæ, sometimes at both extremities, which furnish the means of
rapid locomotion. The spiro-bacteria multiply by spores, although
little is at present known of their life history. They frequently are
attached together at their extremities, forming zigzag chains.
We have seen that bacteria differ greatly in appearance from the
elongated dot of the bacterium proper, to the elongated rod or
cylinder of the bacillus, and the long spirals of spiro-bacteria. It
is unfortunate that they are not sufficiently constant in habit to
always attach themselves to one or the other of these genera. The
micrococcus has a habit of elongating at times until it is impossible
to recognize him except as a bacterium; while bacilli, again, break up
until their particles exactly resemble micrococci.
Bacteria cannot exist without water; certain forms require oxygen,
while others thrive equally well without it; some thrive in solution
of simple salts, while others require albuminoid material.
Bacteriology, with its relation to the science of medicine, is of
importance to every investigating physician; it covers our knowledge
of the relation of these minute organisms to the ætiology of disease.
What has been gained as to practical application in the treatment of
disease? This question is not infrequently asked in a sneering manner.
We can, in reply, say that the results are not all in the future. It
is encouraging that results have been attained which have had a very
important practical bearing, and that these complaints come generally
from individuals least acquainted with scientific investigations in
bacteriology.
In the study of the relation of a given bacterium to a certain
disease, it becomes necessary to attend carefully to three different
operations: First, the organism supposed to cause the disease must be
found and isolated. Second, it must be cultivated through several
generations in order that absolute purity may be secured. Lastly, the
germ must be again introduced into a healthy living being. If the
preceding steps be carried out, and the original disease be
communicated by inoculation, and the germs be again found in the
diseased body, we have no alternative; we must conclude that we have
ascertained the cause of the disease. The importance of being familiar
with the ætiology of the disease before we can expect to combat it
with any well-grounded hope of success is evident.
If the sputum of a phthisical patient be submitted to the skilled
microscopist, he is nearly always able to demonstrate bacilli, but
this goes for very little. Because bacilli are found in phthisis, it
is no more certain that they are the cause of phthisis than it is
certain that cheese mites are the cause of cheese. Well, suppose we
were to inject sputum from a phthisical person into the lower animal
and tuberculosis follows, and then announce to the profession that we
have demonstrated the relation of the cause and effect between bacilli
and phthisis? Why we would start such an uproar of objections as would
speedily convince us that there was much work yet in the domain of
bacteriology.
The scientific investigators would say you have injected with the
sputum into the blood of your unfortunate patient, pus, morphological
elements, and perhaps half a dozen other forms of bacteria, any one of
which is just as likely to produce the disease as the bacillus you
have selected.
The first important step is, first isolate your bacillus. If I were to
take a glass plate, one side of which is coated with a thick solution
of peptonized gelatin, and allow the water to collect, the gelatinous
matter will become solid. If now, with a wire dipped in some
tuberculous matter, I draw a line along the gelatin, I have deposited
at intervals along this line, specimens of tubercle bacilli. If this
plate be now kept at a proper temperature, after a few days, wherever
the bacilli have been caught, a grayish spot will appear, which,
easily seen with the naked eye, gradually spreads and becomes larger.
These spots are colonies containing thousands of bacilli. Let us
return to our gelatin plate.
We find a spot which answers to the description of a colony of
tubercle bacilli. We now take a minute particle from this colony on a
wire and convey it to the surface of some hardened blood serum in a
test tube. We plug the tube so that no air germs may drop in, and
place it in an incubator at the proper temperature. After several
days, if no contamination be present, a colony of bacilli will appear
around the spot where we sowed the spores. Let us repeat the process.
Take a particle from this colony, and transfer it to another tube.
This is our second culture. This must be repeated until we are
satisfied that we have secured a _pure_ culture. If this be carried to
the twenty-fifth generation, we may be assured that there remains no
pus, no ptomaines, nothing but the desired bacilli.
It is a proper material now for inoculation, and if we inoculate some
of the lower animals, for instance the monkey, we produce a disease
identical with phthisis pulmpnalis. Bacteria also afford peculiar
chemical reactions. For example, nitric acid will discharge all the
color from all bacilli artificially dyed with anilin, except those of
tubercle and anthrax. One species is stained readily with a dye that
leaves another unaltered. Thus we are enabled in the laboratory to
determine whether the bacilli found in sputum, for example, are from
tubercle or are the bacteria of decomposition.
From what I have said of the tubercle bacillus, it would seem
thoroughly demonstrated that it is the cause of tubercle in these
animals. But we must walk cautiously here. These are not human beings,
who know that like results would follow their inoculation. The animals
used by Koch are animals very subject to tubercle.
We must, from the very nature of our environment, be constantly
inhaling these germs as we pass through the wards of our hospitals;
yes, they are floating in the air of our streets and dwellings. It
becomes necessary then for us to inquire: If bacteria cause disease,
in what manner do they produce it? The healthy organism is always
beset with a multitude of non-pathogenic bacteria. They occupy the
natural cavities, especially the alimentary canal. They feed on the
substances lying in their neighborhood, whether brought into the body
or secreted by the tissues. In so doing they set up chemical changes
in their substances. Where the organs are acting normally these fungi
work no mischief. The products of decomposition thus set up are
harmless, or are conveyed out of the body before they begin to be
active.
If bacteria develop to an inordinate degree, if the contents of organs
are not frequently discharged, fermentative processes may be set up,
which result in disease. Bacteria must always multiply and exist at
the expense of the body which they infest, and the more weakened the
vital forces become, the more favorable is the soil for their
development.
Septicæmia is caused by the absorption of the products of
putrefaction, induced before bacteria can multiply inside or outside
the body. Bacteria must find a congenial soil. The so-called cholera
bacillus must gain access to the intestinal tract before it finds
conditions suitable to colonization. It does not seem to multiply in
the stomach or in the blood, but once injected into the duodenum
develops with astonishing rapidity, and the delicate epithelial cells
of the villi become swollen, soften and break down, exposing the
mucosa.
It has been shown that _bouillon_ in which Loeffler's diphtheria
bacillus has grown, and which has been passed through unglazed
porcelain filters, shows the presence of a poison which is capable of
producing the same results upon inoculation as the pure culture of the
bacillus itself. Zarniko, working upon the same organism, obtained a
number of positive results that led him to declare this bacillus is
the cause of epidemic diphtheria, in spite of many assertions to the
contrary. Chantmesse and Widal record the results of their work as to
what will most easily and effectively destroy the bacillus of
diphtheria.
The only three substances that actually checked and destroyed its
vitality were phenic acid (5 per cent.), camphor (20 per cent.), olive
oil (25 per cent.), in combination. For the last I substitute
glycerine, because this allows the mixture to penetrate farther into
the mucous membrane than oil, the latter favoring a tendency to pass
over the surface. This mixture when heated separates into two layers,
the upper one viscid and forming a sort of "glycerol," the lower
clear. The latter will completely sterilize a thread dipped in a pure
culture of the diphtheria bacillus. Corrosive sublimate was not
examined because in strong enough doses it would be dangerous and in
weaker ones it would be useless.
The facts obtained in regards to the streptococcus of erysipelas are
reported as follows: That both chemical and experimental evidence
teach the extreme ease of a renewed attack of the disease; that it is
possible to kill guinea pigs by an intoxication when they are immune
to an inoculation of the culture in ordinary quantities. And this
latter fact should warn experimenters trying to obtain immunity in man
by the inoculation of non-pathogenic bacteria, because the same
results may be reached.
A new theory in regard to fevers and the relation of micro-organisms
is suggested by Roussy, viz.: That it is a fermentation produced by a
diastase or soluble ferment found in all micro-organisms and cells,
and which they use in attacking and transforming matter, either inside
their substance or without it.
The resemblance of the malaria parasite to that of recurrent fever is
noted in the work of Sacharoff. He states that there exists in the
blood of those suffering from recurrent fever a hæmatozoon, which is
most prominent after the fever has begun to fall, when it is of
enormous proportions, twenty or more diameters of a red blood
corpuscle, although smaller ones may still be found. The parasite
consists of a delicate amoeboid body containing a multitude of dark,
round, uniform, sharply outlined, movable granules. Besides these, the
protoplasm contains a generally grayish homogeneous nucleus as large
as one or two red blood corpuscles. The protoplasm sends out
pseudopodia (with granules), which sometimes separate and appear as
small delicate pieces of protoplasm. They vary in size, and are often
swallowed by the red blood corpuscles in which they grow, and finally
develop into the above mentioned amoeboid bodies.
Prof. J. Lewis Smith has made a great many autopsies of children dead
from cholera infantum, and almost invariably found the stomach and
liver in a comparatively healthy condition. Ganghen, who has given
this subject considerable study, denies the existence of any specific
germ in the summer diarrhea of infants, but claims to have found three
different germs in the intestines of children suffering from cholera
infantum, each producing a chemical poison which is capable of
producing vomiting, purging, and even death. A great variety of germs
are found in drinking water, and no doubt countless numbers are taken
into the digestive tract, and the principal reason why pathological
conditions do not occur more frequently is on account of the
germicidal qualities of the gastric juice.
The comma bacillus of Koch, and the typhoid fever germ of Eberth, are
especially destroyed in normal gastric juice. When the germs are very
numerous, they run the gauntlet of the stomach (as the gastric juice
is secreted only during digestion); and once in the alkaline
intestinal canal they are capable of setting up disease, other
conditions contributing--ill health, deranged digestion, etc.
Mittnam has made a study of bacteria beneath the nails, and reports,
after examining persons following different occupations, having found
numerous varieties of micro-organisms; which are interesting from a
scientific standpoint relative to the importance of thoroughly
cleansing the hands before undertaking any surgical procedure. He
found, out of twenty-five experiments, 78 varieties of bacteria, of
which 36 were classed as micrococci, 21 diplococci, 18 rods, 3
sarcinæ, and 1 yeast. Cooks, barbers, waiters, etc., were examined.
The blood, defibrinated and freshly drawn, has marked germicidal
action; for bacteria its action is decidedly deadly, even hours after
it has been drawn from the body. Especially were anti-germic qualities
noticed upon pathogenic bacteria. Buchner put the bacilli of anthrax
in a quantity of blood, and in two hours the number was reduced from
4,800 to 56, and in three hours only 3 living bacteria remained. Other
bacteria were experimented upon in blood with similar results, but the
destruction of the organism from putrefaction was much less marked,
and on some varieties the blood had little or no action.
It is not the object of these remarks to even give a _résumé_ of the
_status præsens_ of bacteriology, but simply to stimulate thought in
that direction. The claims of some of the ultra-bacteriologists may
never be realized, but enough has been accomplished to revolutionize
the treatment of certain diseases, and the observing student will do
well to keep his eye on the microbe, as it seems from the latest
investigations that its star is in the ascendant. And who can
prognosticate but that in the next decade an entire revolution in the
ætiology and treatment of many diseases may take place?
Detroit, Mich.
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