Scientific American Supplement, No. 458, October 11, 1884 by Various
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Various >> Scientific American Supplement, No. 458, October 11, 1884
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[Footnote 1: A detailed report is published in the _Berliner Klinische
Wochenschrift_ Aug. 4.]
Dr. Koch commenced by remarking that what was required for the prevention
of cholera was a scientific basis. Many and diverse views as to its mode
of diffusion and infection prevailed, but they furnished no safe ground
for prophylaxis. On the one hand, it was held that cholera is a specific
disease originating in India; on the other, that it may arise
spontaneously in any country, and own no specific cause. One view regards
the infection to be conveyed only by the patient and his surroundings; and
the other that it is spread by merchandise, by healthy individuals, and by
atmospheric currents. There is a like discrepancy in the views on the
possibility of its diffusion by drinking water, on the influence of
conditions of soil, on the question whether the dejecta contain the poison
or not, and on the duration of the incubation period. No progress was
possible in combating the disease until these root questions of the
etiology of cholera are decided.
Hitherto the advances in knowledge upon the etiology of other infective
diseases have done little toward the etiology of cholera. These advances
have been made within the last ten years, during which time no
opportunity--at least not in Europe--has occurred to pursue researches;
and in India, where there is abundant material for such research, no one
has undertaken the task. The opportunity given by the outbreak of cholera
in Egypt last year to study the disease before it reached European soil
was taken advantage of by various governments, who sent expeditions for
the purpose. He had the honor to take part in one of these, and in
accepting it he well knew the difficulties of the task before him, for
hardly anything was known about the cholera poison, or where it should be
sought; whether it was to be found only in the intestinal canal, or in the
blood, or elsewhere. Nor was it known whether it was of bacterial nature,
or fungoid, or an animal parasite--e.g., an amoeba. But other difficulties
appeared in an unexpected direction. From the accounts given in text-books
he had imagined that the cholera intestine would show very slight changes,
and would be filled with a clear "rice-water" fluid. He had not fully
recollected the conditions met with in post-mortem examinations had
formerly made, and was therefore at first surprised to meet with quite a
different state of things. For he soon found that in a large majority of
cases remarkably severe lesions were present in the intestines. In other
cases the changes were slighter, and eventually he met with some which, to
a certain extent, corresponded with the type described in text-books. But
it was some time, and after many inspections, before he was enabled to
correctly interpret the varied changes met with. In spite of a most
careful examination of all other organs and of the Mood, nothing was found
to establish the presence of an infective material, and attention was
finally concentrated on the intestinal conditions.
There were cases in which the lower segment of the small intestine, most
marked immediately above the ileocaecal valve, extending thence upward, was
of a dark reddish-brown color, the mucous membrane being covered with
superficial haemorrhages. In many cases the mucous membrane appeared to be
superficially necrosed, and covered with diphtheritic patches. The
intestinal contents in such cases were not colorless, but consisted of a
sanguinolent, ichorous, putrid fluid. Other cases showed a gradual
transition to a less marked change. The redness was less intense, and was
in patches, while in others the injection was limited to the margins of
the follicular and Peyerian glands, giving an appearance which is quite
peculiar to cholera. In comparatively few cases were the changes so slight
as to consist in a somewhat swollen and opaque condition of the
superficial layers of the mucous membrane, with delicate rosy-red
injection, and some prominence of the solitary follicles and Peyer's
patches. In such cases the intestinal contents were colorless, but
resembling meal-soup rather than rice-water. In only a solitary instance
were the contents watery and mucoid. Microscopical examination of the
intestine and its contents revealed, especially in the cases where the
margins of Peyer's patches were reddened, a considerable invasion of
bacteria, occurring partly within the tubular glands, partly between the
epithelium and basement membrane, and in some parts deeper still. Then he
found cases in which, besides bacteria of one definite and constant form,
there were others also accumulated within and around the tubular glands,
of various size, some short and thick, others very fine; and be soon
concluded that he had to do here with a primary invasion of pathogenic
bacilli, which, as it were, prepared the tissues for the entrance of the
non-pathogenic forms, just as he had observed, in the necrotic,
diphtheritic changes in the intestinal mucosa and in typhoid ulcers.
Passing to speak of the microscopical character of the contents of the
bowel, Dr. Koch said that owing to the sanguinolent and putrescent
character of these in the cases first examined, no conclusion was arrived
at for some time. Thus he found multitudes of bacteria of various kinds,
rendering it impossible to distinguish any special forms, and it was not
until he had examined two acute and uncomplicated cases, before haemorrhage
had occurred, and where the evacuation had not decomposed, that he found
more abundantly the kind of organism which had been seen so richly in the
intestinal mucosa. He then proceeded to describe the characters of this
bacterium. It is smaller than the tubercle bacillus, being only about half
or at most two-thirds the size of the latter, but much more plump,
thicker, and slightly curved. As a rule, the curve is no more than that of
a comma (,) but sometimes it assumes a semicircular shape, and he has seen
it forming a double curve like an S, these two variations from the normal
being suggestive of the junction of two individual bacilli. In cultures
there always appears a remarkably free development of comma shaped
bacilli. These bacilli often grow out to form long threads, not in the
manner of anthrax bacilli, nor with a simple undulating form, but assuming
the shape of delicate long spirals, a corkscrew shape, reminding one very
forcibly of the spirochaete of relapsing fever. Indeed, it would be
difficult to distinguish the two if placed side by side. On account of
this developmental change, he doubted if the cholera organism should be
ranked with bacilli; it is rather a transitional form between the bacillus
and the spirillum. Possibly it is a true spirillum, portions of which
appear in the comma shape, much as in other spirilla--_e. g_., spirilla
undula, which do not always form complete spirals, but consist only of
more or less curved rods. The comma bacilli thrive well in meat infusion,
growing in it with great rapidity. By examining, microscopically, a drop
of this broth culture the baccilli are seen in active movement, swarming
at the margins of the drop, interspersed with the spiral threads, which
are also apparently mobile. They grow also in other fluids--_e. g_., very
abundantly in milk, without coagulating it or changing its appearance.
Also in blood serum they grow very richly.
Another good nutrient medium is gelatine, wherein the comma bacilli form
colonies of a perfectly characteristic kind, different from those of any
other form of bacteria. The colony when very young appears as a pale and
small spot, not completely spherical as other bacterial colonies in
gelatine are wont to be, but with a more or less irregular, protruding, or
jagged contour. It also very soon takes on a somewhat granular appearance.
As the colony increases, the granular character becomes more marked, until
it seems to be made up of highly refractile granules, like a mass of
particles of glass. In its further growth the gelatine is liquefied in the
vicinity of the colony, which at the same time sinks down deeper into the
gelatine mass, and makes a small thread-like excavation in the gelatine,
in the center of which the colony appears as a small white point. This
again is peculiar; it is never seen, at least so marked, with any other
bacterium. And a similar appearance is produced when gelatine is
inoculated with a pure culture of this bacillus, the gelatine liquefying
at the seat of inoculation, and the small colony continually enlarging;
but above it there occurs the excavated spot, like a bubble of air
floating over the bacillary colony. It gives the impression that the
bacillus growth not only liquefies the gelatine, but causes a rapid
evaporation of the fluid so formed. Many bacteria also have the power of
so liquefying gelatine with which they are inoculated, but never do they
produce such an excavation with the bladder-like cavity on the surface.
Another peculiarity was the slowness with which the gelatine liquefied,
and the narrow limits of this liquefaction in the case of a gelatine disk.
Cultures of the comma bacillus were also made in agar-agar jelly, which is
not liquefied by them. On potato these bacilli grow like those of
glanders, forming a grayish-brown layer on the surface. The comma bacilli
thrive best at temperatures between 30 deg. and 40 deg. C., but they are not very
sensitive to low temperatures, their growth not being prevented until 17 deg.
or 16 deg. C. is reached. In this respect they agree with anthrax bacilli.
Koch made an experiment to ascertain whether a very low temperature not
merely checked development but killed them, and subjected the comma
bacilli to a temperature of 10 deg. C. They were then completely frozen, but
yet retained vitality, growing in gelatine afterward. Other experiments,
by excluding air from the gelatine cultures, or placing them under an
exhausted bell jar, or in an atmosphere of carbonic acid, went to prove
that they required air and oxygen for their growth; but the deprivation
did not kill them, since on removing them from these conditions they again
began to grow.
The growth of these bacilli is exceptionally rapid, quickly attaining its
height, and after a brief stationary period as quickly terminating. The
dying bacilli lose their shape, sometimes appearing shriveled, sometimes
swollen, and then staining very slightly or not at all. The special
features of their vegetation are best seen when substances which also
contain other forms of bacteria are taken--_e. g_., the intestinal
contents or choleraic evacuations mixed with moistened earth or linen and
kept damp. The comma bacilli in these conditions multiply with great
rapidity so as to far outnumber the other forms of bacteria, which at
first might have been in far greater abundance. This state of affairs does
not last long; in two or three days the comma bacilli began to die off,
and the other bacteria began to multiply. Precisely the same thing takes
place in the intestine, where, after the rapid initial vegetation is over,
and when exudation of blood occurs in the bowel, the comma bacilli
disappear and putrefactive bacteria predominate. Whether the occurrence of
putrefaction is inimical to the comma bacilli has not been proved, but
from analogy it is very probable. At any rate, it is important to know
this for certain, for if it be so, then the comma bacilli will not thrive
in a cesspit, and then further disinfection would be unnecessary. These
bacilli thrive best in fluids containing a certain amount of nutriment.
Experiments have not yet shown the limits in this respect, but Koch has
found them capable of growing in meat broth diluted ten times.
Again, if the nutrient medium become acid in reaction their growth is
checked, at least in gelatine and meat infusion; but singularly enough,
they continue to grow on the surface of a boiled potato which has become
acid, showing that all acids are not equally obnoxious to them. But here,
as with other substances which hinder their growth, they do not kill the
bacilli. Davaine has shown that iodine is a strong bactericide. He
experimented with anthrax bacilli in water to which iodine was added, and
the bacilli were destroyed. But practically the organisms have to be dealt
with in the alkaline contents of the bowel, or in the blood or fluids of
the tissues, where iodine cannot remain in the free state. Koch found that
the addition of an aqueous solution of iodine (1 in 4,000) to meat
infusion, in the proportion of 1 in 10, did not in the least interfere
with the growth of the bacilli in that medium. He did not pursue this line
of inquiry, seeing that in practice larger quantities of iodine than that
could not be given. Alcohol first checks the development of the comma
bacilli when it is mixed with the nutrient fluid in the proportion of 1 in
10, a degree of concentration which renders it impracticable for
treatment. Common salt was added to the extent of 2 per cent. without
influencing the growth of the bacilli. Sulphate of iron, in the proportion
of 2 per cent., checks this growth, probably by precipitating albumimites
from the fluids, and possibly also by its acid reaction; certainly it does
not seem to have any specific disinfecting action--i.e., in destroying the
bacilli. Indeed, Koch thinks that the admixture of sulphate of iron with
faecal matter may arrest putrefaction, and really remove what may be the
most destructive process to the comma bacilli. Hence he would distinguish
between substances which merely arrest putrefaction and those which are
bactericidal; for the former may simply serve the purpose of preserving
the infective virus. Among other substances which prevent the growth of
the comma bacilli may be mentioned alum, in solutions of the strength of 1
in 100; camphor, 1 in 300; carbolic acid, 1 in 400; oil of peppermint, 1
in 2,000; sulphate of copper, 1 in 2,500 (a remedy much employed, but how
much would really be needed merely to hinder the growth of the bacilli in
the intestine!); quinine, 1 in 5,000; and sublimate, 1 in 100,000. In
contrast with the foregoing measures for preventing the growth of these
bacilli is the striking fact that they are readily killed by drying. This
fact is proved by merely drying a small drop of material containing the
bacilli on a cover-glass, and then placing this over some of the fluid on
a glass slide. With anthrax bacilli vitality is retained for nearly a
week; whereas, the comma bacillus appears to be killed in a very short
time. Thus it was found that although vitality was retained--depending
largely upon the number of bacilli--for a short time, yet withdrawal of
the nutrient fluid for an hour or even less often sufficed; and it never
happened that the bacilli retained vitality after a deprivation lasting
twenty-four hours. These results would seem to point to the fact that the
comma bacillus does not, like the organisms of anthrax and vaccinia, pass
into the resting state (Daner-zustande) by drying; and if so, it is one of
the most important facts in the etiology of cholera. Much, however,
remains to be done, especially with regard to the soiled linen of cholera
patients being kept in a damp state. He found that in soiled articles,
when dried for a time, varying from twenty-four hours and upward, the
comma bacilli were quite destroyed. Nor was the destruction delayed by
placing choleraic excreta in or upon earth, dry or moist, or mixed with
stagnant water. In gelatine cultures the comma bacilli can be cultivated
for six weeks, and also in blood serum, milk, and potato, where anthrax
bacilli rapidly form spores. But a resting state of the comma bacilli has
never been met with--a very exceptional thing in the case of bacilli, and
another reason why the organism must be regarded rather as a spirillum
than a bacillus, for the spirilla require only a fluid medium, and do not,
like the anthrax bacilli, thrive in a dry state. It is quite unlikely that
a resting state of the comma bacillus will ever be discovered; and,
moreover, its absence harmonizes with our knowledge of cholera
etiology.--_The Lancet_.
* * * * *
[THE MEDICAL RECORD.]
MALARIA.--THE NATURAL PRODUCTION OF MALARIA, AND THE MEANS OF MAKING
MALARIAL COUNTRIES HEALTHIER.
[Footnote: An Address delivered at the Eighth Session of the International
Medical Congress, Copenhagen, August 12, 1884.]
By Conrad Tommasi Crudeli, M.D., Professor of Hygiene, University of Rome,
Italy.
Before entering upon my subject, I must crave the indulgence of those of
my colleagues whose language I have borrowed for any italicisms that I may
use, as well as for the foreign accent which must strike their ears more
or less disagreeably. Desiring to respond as well as lay in my power to
the invitation with which I have been honored to discuss the hygienic
questions relating to malaria, I have chosen the French language as being
the one in which, apart from my mother tongue, I could express myself with
the greatest ease and precision.
I shall be pardoned also, I hope, for having employed the terms "malaria"
and "malarial districts" in place of the more commonly used expressions
"paludal miasm" (_miasme paludeen_) and "marshy regions" (_contrees
marecageuses_). The substitution is not a happy one from a literary point
of view, but I have made it deliberately and for the following reason: The
idea that intermittent and pernicious fevers are engendered by putrid
emanations from swamps and marshes is one of those semi-scientific
assumptions which have contributed most to lead astray the investigations
of scientists and the work of public administrations. This idea, so
widespread and so well established by the traditions of the school, is
radically false. The specific ferment which engenders those fevers by its
accumulation in the atmosphere which we breathe is not exclusively of
paludal origin, and still less is it a product of putrefaction. Indeed, in
every region of the globe between the two Arctic circles there are swamps
and marshes, steeping-tanks of hemp and flax, large deltas where salt and
fresh waters mix, and yet there is no malaria there, although putrid
decomposition is on every side. On the other hand, in the same parts of
the globe there are places which are not and never were marshy, and in
which there is not the least trace of putrefaction, but which,
nevertheless, produce malaria in abundance. I reject, therefore, wholly
the paludal assumption, and in order to express this view in the title of
my paper, have been forced to employ terms which to my hearers may sound
like italicisms.
The Italians generally have not this paludal notion, for experience taught
them long ago that malaria is produced nearly everywhere--in marshy
districts as well as in those which might almost be called arid; in a
volcanic soil as well as in the deposits of the Miocene and Pliocene
periods and the ancient and modern alluvia; in a soil rich in organic
matters as well as in one containing almost none; in the plains as well as
on the hills or mountains. The word malaria (bad air), which it is the sad
privilege of Italy to have lent to all languages to express the cause of
intermittent and pernicious fevers, represents, then, among the majority
of our rural populations, the idea of an agent which may infect any sort
of country, whatever may be its hydraulic and topographical conditions,
and whatever may be its geological formation. This word, therefore, is the
one best suited to designate this specific ferment in question, and I have
on this account, employed it and its adjectival derivatives in order not
to resuscitate the idea of the exclusively paludal origin of the morbific
agent.
I shall not tarry long to speak of the nature of this ferment, for the
studies bearing upon that point, although far advanced, are not yet
completed. I may remark, however, that the idea that the ferment is formed
of living organisms is a very old one, and has not arisen suddenly because
of the modern theories of the parasitic nature of disease. From the time
of Varrar (who believed that malaria was made up of invisible mites
suspended in the atmosphere) to our own day this theory has been several
times advanced by hygienists. Independently of the general considerations
which led Rasori, and later Henle, to formulate the doctrine of the
_contagium vivum_ of infection (long before the progress of microscopical
science had revealed the existence of living ferments), there were
peculiar circumstances as regards malaria which should have impelled minds
to look in that direction, even in times long past.
Some of these circumstances are of a nature to strike every serious
observer, and deserve a few moments' attention. How could one maintain,
for example, that this ferment is a product of chemical reactions taking
place in the ground, when it is seen to remain constantly the same
whatever may be the composition of the soil from which it emanates! As
long as the paludal theory held sway, the chemical interpretation of this
identity of the product in every latitude was easy. Rica does not hesitate
to admit that when a swampy tract is heated by the sun's rays to the
necessary point for the putrid decomposition of the organic matters
contained in it, the "chemical ferment," or rather the "mephitic gases,"
to which is attributed the morbific action, are developed, whatever may be
the distance from the equator at which this marshy region lies. But since
it has been ascertained that malaria is produced in soils of the most
varied chemical composition, _the persistent identity of this product_ has
become chemically inexplicable; while it is however readily conceivable,
if one admits that malaria is an organized ferment which easily finds the
necessary conditions for its life and multiplication in the most varied
soils, as is the case with millions of other organisms vastly superior to
the rudimentary vegetables which constitute the living ferments.
The same thing may be said of _the progressive intensity of the morbific
production in abandoned malarious districts_. This fact has been
historically proved in several parts of the earth, and especially in
Italy. A large number of Grecian, Etruscan, and Latin cities, even Rome
itself, sprang up in malarious territories and attained a high state of
prosperity. First among the reasons for this success must be placed the
works undertaken with a view of rendering these places more salubrious,
and which lessened the evil production, _but almost never extinguished it
completely_. After the abandonment of these localities, the production of
malaria recommenced in a degree which went on increasing from age to age,
and which has rendered some of these places actually uninhabitable. This
was seen, in the time of the ancient Romans, in Etruria, when it was
conquered and laid waste, and in several parts of Magna Graecia, and of
Sicily. From the fall of Rome even to the present day, this phenomenon has
been manifested in a very evident manner in the Roman Campagna, in certain
parts of which, even up to the time of the Renaissance, it was possible to
maintain pleasure houses, but which are now unhabitable during the hot
season. In many cases the physical conditions of the soil have undergone
no appreciable change during centuries, so that it is impossible to
attribute so enormous an augmentation of malaria to an increase in its
annual production, itself increased by a progressive alteration of the
chemical composition of the soil. But if, on the contrary, it be admitted
that malaria is caused by a living organism whose successive generations
accumulate in the soil, the interpretation of this fact becomes very
simple.
There are, finally, _peculiarities in the local charging of the atmosphere
with malaria_ which can be explained only in this manner. If the malarial
miasm were composed of gaseous bodies emanating from the soil, or rather
of chemical ferments formed beneath the ground and raised into the air by
gases or watery vapor, the charging of the atmosphere with the specific
poison ought to arrive at its maximum during the hottest part of the day,
when the ground is heated the most by the sun's rays, and when the
evaporation of water and all chemical actions attain their maximum
intensity. But this is very different from what actually occurs. The local
charging of the atmosphere is always less strong during the meridian hours
than at the beginning and the end of the day, that is to say, after the
rising, and especially after the setting, of the sun. Now it is precisely
at these hours that the difference between the temperature of the lower
layers of the atmosphere and that of the surface of the ground is the
greatest, and that the ascending currents of air starting from the ground
are the strongest. If malaria consists of solid particles contained in the
soil, one may readily understand how their elevation _en masse_ into the
atmosphere should take place especially at these two periods of the day.
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