a necessary result of Villemin's[62] experiment, in which the rabbit
became tuberculous after inoculation with fragments of the pearly
tumor. Gerlach,[63] and especially Schüppel,[64] showed that the
structure of the nodules of the pearly distemper is the same as that
of the tubercles of man, and that the two diseases are identical from
the histological point of view.
[Footnote 62: _Op. cit._, 537.]
[Footnote 63: _Virchow's Archiv_, 1870, li. 290.]
[Footnote 64: _Ibid._, 1872, lvi. 38.]
From the anatomical identification and the etiological connection, as
shown by Villemin, Gerlach, and Aufrecht, the pearly distemper became
designated as a bovine tuberculosis.
The experiments of Villemin were further productive in leading to the
discovery by Koch of the bacillus tuberculosis. It was early obvious
that certain cheesy material and gray tubercles possessed the
infectious qualities, and Villemin[65] maintained that the immediate
cause of the latter was a germ introduced from without, which
propagated and perpetuated itself in man and certain animals. This
view acquired prominence through the investigations of Klebs, who in
1877 claimed to have isolated the micrococci which produced tubercles
when injected into animals. Three years later Schüller[66] confirmed
the statements of Klebs, and asserted that he had been enabled to
obtain infective micrococci by cultivation from {100} miliary
tubercles, scrofulous glands and joints, and from the tissue of lupus.
Aufrecht[67] found micrococci, single and in chains, and short
glistening rods, within tubercles resulting from inoculation with
material from pearly tumors. The same organisms were found in
tubercles produced by the inoculation of tubercles from man, and he
regarded these rod-shaped bodies as the specific element productive of
miliary tuberculosis.
[Footnote 65: _Op. cit._, 620.]
[Footnote 66: _Op. cit._, 55.]
[Footnote 67: _Pathologische Mittheilungen_, 1881, p. 43.]
The isolation of the virus of tubercle was thus regarded as an open
question till the announcement by Koch[68] of the constant presence of
a hitherto unknown, characteristic, well defined organism in all
tuberculous affections, which, when isolated and introduced into
animals, produced tuberculosis, the resulting tubercles likewise
containing the organism.
[Footnote 68: _Berliner klinische Wochenschrift_, 1882, p. 15.]
The latter, the bacillus tuberculosis, was to be seen in preparations
methodically treated and carefully stained with aniline colors, by all
of which, excepting the browns, the bacillus was tinged. It was found
in miliary tubercles of the lung, cerebral and intestinal tubercle,
cheesy bronchitis and pneumonia, phthisical sputa, scrofulous glands,
and fungous inflammation of the joints. It was also seen in the
nodules of pearly distemper and in the cheesy masses from the lungs of
cattle. It was furthermore met with in the cheesy lymphatic glands of
swine, in the tubercular nodules of a fowl, and in the tubercles of
guinea-pigs, rabbits, and monkeys. The bacilli were likewise found in
the tubercles resulting from the inoculation of animals with
tubercular virus from its various sources.
The microphytes were described as very slender rods, varying in length
from one-fourth the diameter of a red blood-corpuscle to its entire
diameter, and spores were occasionally seen within the rods. In shape
and size they resembled the bacilli of leprosy, but the latter were
narrower and pointed at the ends. They were found in greatest
abundance when the tuberculous process was recent and rapidly
advancing, and were present within, as well as between, cells. The
younger giant-cells contained them in larger numbers than the older
forms. They were present at the periphery of cheesy nodules rather
than at the centre.
The bacilli were cultivated through successive generations and
required a temperature of between 30° C. and 41° C. (86° F.-105.8° F.)
for their development, one of 37° C. or 38° C. (98.6° F. or 100.4° F.)
being the most favorable. The crop first became apparent on the tenth
day after sowing, and the growth extended through a period of three to
four weeks, forming a compact scale. The cultivated bacilli, even
propagated through several generations, when inoculated, produced the
same positive results as follow the inoculation of fragments of
tuberculous material, although animals might be used which are not
easily infected with tuberculosis.
Koch's publication was immediately followed by a statement from
Baumgarten[69] of his discovery of rod-like bacteria in the tubercles
of rabbits resulting from the inoculation with pearly masses, and in
the pleural and pericardial tubercles of man. They were made evident
by treating the sections for microscopic examination with very dilute
solutions of soda or potash.
[Footnote 69: _Centralblatt für die med. Wissenschaften_, 1882, xv.
257.]
{101} The discoveries of Koch thus show that the production of
tuberculosis is dependent upon the presence of distinctive bacilli,
and that these bacilli are present not only in miliary tubercles, but
in scrofulous glands and joints, in cheesy inflammation of the lungs,
and in the pearly distemper of animals. The identification of
tuberculosis with the pearly distemper and certain scrofulous
affections is thus established from the etiological as well as the
histological point of view.
As the bacilli are to be regarded as the virus of tuberculosis, so
their introduction into the human body is necessary for the production
of this disease in man. It is obvious, however, that other factors
than the virus are necessary, for not every one exposed to the
reception of tubercular bacilli becomes tuberculous. It may well be
that scrofula is still to be regarded as that condition of the solids
and liquids of the body which offers favorable opportunities for the
retention and growth of the bacilli, and thus for the production of
tuberculosis. Formad[70] claims that he has discovered structural
peculiarities of tissue as a cause for the scrofulous habit, which he
regards as synonymous with a predisposition to tuberculosis. These
peculiarities are manifested by a narrowness of the lymph-spaces and
their partial obliteration by cellular elements. He also maintains
that these features are not only of congenital origin, but may be
acquired through malnutrition and confinement.
[Footnote 70: _Studies from the Pathological Lab. of the Univ. of
Penna._, reprint, 1882, xi. 3.]
The occurrence of a local, circumscribed tuberculosis in extreme old
age, without antecedent or other concurrent evidence of scrofulous
disturbances, suggests that favorable opportunities for the
development of the tubercular bacillus may arise in advancing years.
In like manner, the frequent termination in phthisis of cases of
diabetes suggests the likelihood of tuberculous inflammation arising
in the absence of any evidence of previous scrofulous or tuberculous
disease. The scrofulous condition or constitution, as indicated by
vulnerable tissues, with a protracted course of inflammations, and a
persistence of their products, with a tendency to cheesy degeneration,
may still exist without a sign of tuberculosis. Those who claim that
scrofula and tuberculosis are identical must, in the light of Koch's
discovery, demonstrate the presence of the bacillus in all scrofulous
inflammations, and deny the existence of scrofula apart from
indisputable manifestations of the activity of the bacilli of
tuberculosis. It may be that such evidence will be presented; until it
is collected scrofula and tuberculosis are to be regarded as distinct
though often coexistent. The scrofulous person is frequently
tuberculous, the tuberculous person is usually scrofulous; the
non-scrofulous person, however, may die of tuberculosis, while the
individual may be scrofulous without containing tubercle.
The actual inheritance of tuberculosis is very unlikely, although this
disease is frequently found in successive generations of a single
family. The various members of the family are rather to be regarded as
furnishing a suitable soil for the growth of the tubercular bacillus,
and their exposure to its seed is favored by the existence of
tuberculosis in one or more members of the household. The scrofulous
condition is still to be regarded as hereditary as well as acquired,
and the scrofulous remain as the class to be especially protected from
the reception and effects of the bacilli of tuberculosis.
{102} It is obviously a matter of importance to determine in any given
case of phthisis whether bacilli are present or absent. A ready means
of ascertaining this fact is offered by the examination of the sputum
in cases of pulmonary phthisis, the feces in intestinal phthisis, the
urine in renal phthisis, and the aspirated pus in cases of supposed
tuberculosis of the joints. Koch has found in examining the sputa from
numerous cases of phthisis that the bacilli were present in one-half
the number, and that they were absent from the sputa of individuals
who were not phthisical. Balmer and Fraentzel[71] have found bacilli
in the sputum from one hundred and twenty cases of phthisis, and
concluded that the progress of a case of pulmonary tuberculosis might
be readily determined from the number and degree of development of the
typical bacilli present in the sputum. The more numerous and
well-developed bacilli, with distinct and constant spores, were found
in the graver cases, which advanced more rapidly. The sputum of the
protracted cases contained few, small, and thin bacilli with scanty
spores. The presence of fever was associated with numerous bacilli,
while its absence was noted in those cases where but few were present.
[Footnote 71: _Berliner klinische Wochenschrift_, 1882, xlv. 679.]
The bacilli are readily detected by means of the staining method
devised by Koch. Various modifications have been presented from time
to time, of which that of Ehrlich[72] has proved the most
satisfactory. The essential features are to obtain a dry, thin layer
of a selected portion of the suspected sputum, which is then to be
deeply stained with fuchsin or methyl-violet; the excess of color is
to be removed with nitric acid, and the preparation is then ready for
examination with the microscope. A power of four or five hundred
diameters is sufficient for the recognition, and the object should be
illuminated with a flood of light through a large diaphragm or an
achromatic condenser. The bacillus retains the color notwithstanding
its exposure to the acid, and the violet colors are more strongly
presented if the preparation is tinted yellow after the action of the
acid. If the bacilli are stained red with fuchsin, the background
should be made blue. It is important that the reagents should be
freshly prepared and filtered, that other bacteria may not obscure the
picture, and that all the apparatus employed should be thoroughly
clean.
[Footnote 72: _Allg. med. Centr. Zeitung_, 1882, xxxvii. 458.]
A fragment of thick, opaque sputum is to be taken in forceps, placed
on a cover-glass, and spread into a thin layer by means of a second
cover-glass. The prepared slide is then to be passed slowly through an
alcoholic flame, or that of a Bunsen burner, till the layer of sputum
is dried. A saturated alcoholic solution of methyl-violet or fuchsin
is made and filtered, and added, drop by drop, to a filtered,
saturated solution of aniline oil shaken in water. The color is to be
added with stirring till an opalescent film forms on the surface of
the mixture. The slide containing the dried sputum is to be placed in
or on this staining fluid, and allowed to remain for half an hour or
less, the application of warmth hastening the process, when it is
removed, and the specimen is decolorized in a solution of one part of
nitric acid and two parts of water. The preparation is then washed in
water, and may be examined directly in water, glycerin, or, after
dehydration in alcohol, in oil of cloves. The tinted bacilli are made
more prominent by a secondary staining, for a minute or two, of the
red (fuchsin) preparation {103} in a concentrated solution of
methyl-blue, the violet preparation being secondarily stained in a
like solution of aniline-brown. If the preparation is to be
permanently preserved, it should be dehydrated in strong alcohol after
washing with water, and it may then be treated with oil of cloves and
mounted in Canada balsam.
After the observer has become thoroughly familiar with the tubercle
bacilli by means of the method of Ehrlich, much time may be saved by
following that of Baumgarten.[73] The cover-glass bearing the dried
sputum is placed in a very dilute solution of caustic potash (two
drops of a 33 per cent. solution in a watch-glass of distilled water)
till the layer of sputum becomes transparent. The cover is then placed
on a slide moistened with a drop of water, tapped slightly, and
examined with the microscope. The bacilli are readily seen, and may be
differentiated from other varieties of bacteria, if necessary, by
again drying the object and examining it in a drop of a dilute watery
solution of aniline-violet or of other preparations of aniline used
for staining nuclei. The tubercle bacilli remain unstained, while
putrefactive bacteria are tinted.
[Footnote 73: _Centralblatt für die med. Wissenschaften_, 1882, xxv.
433.]
The tubercular products of the invasion of the body by the bacillus
tuberculosis are regarded as primary or secondary, according as they
are present at that part of the body which directly receives the
organisms or as they are dependent upon the transfer of the latter to
parts remote from the region of their admission and immediate effects.
This differing relation is also expressed by the terms local and
general tuberculosis. In the former the bacilli excite the growth of
tubercle only at a given part of the body. Their apparent effects may
be wholly limited to this region, and it not rarely happens that the
same is quite distant from the channels through which the bacilli are
admitted. A general tuberculosis occurs when the latter are
disseminated over the body, and their effects, especially the
production of numerous tubercles, are found at various parts. The
dissemination may take place at the time of entrance, or, as is more
commonly the case, apparently occurs at some subsequent period, the
immediate disturbances being localized at a given portion of the body.
The necessary conditions being here offered for the propagation of the
bacilli, their sudden distribution in great numbers is afterward
permitted when favorable opportunities arise for their absorption.
Such conditions are present when the local tubercular growths extend
into lymphatics or blood-vessels. The frequency with which scrofulous
glands are tuberculous--that is, contain miliary tubercles--is already
fully recognized, and a tuberculosis of the lymphatic glands is
essentially regional. These glands become affected in consequence of
disturbances, the local effects of which may have wholly disappeared,
in the region from which they receive their lymph. The cervical glands
become permanently enlarged, perhaps tuberculous, in connection with
persistent or recurrent inflammatory processes in the tonsils and
pharynx, the bronchial glands from similar bronchial or pulmonary
affections, and the mesenteric glands from like intestinal
disturbances. In such instances, the direct reception of the bacilli
into the lymph-current is assumed rather than demonstrated from a
knowledge of the possibilities of absorption and an appreciation of
the conditions in the glands.
That an actual growth of tubercles from the wall of the intestinal
{104} lymphatics may take place has long been known, and Ponfick has
recently discovered that tubercles may be found growing from the wall
of the thoracic duct. The possibility of the direct admission into the
lymph-current of the infective element in tuberculosis is thus
apparent, and its indirect entrance into the blood-current is equally
obvious. That the bacillus of tubercle may be directly received into
the blood-current is likewise evident from the observations of
Weigert, who found tubercles growing from the walls of the pulmonary
blood-vessels, venous as well as arterial. This discovery of a
tuberculosis of the blood-vessels was confirmed by Klebs, who had
found a tuberculosis of the azygos veins. The occurrence of multiple
miliary tubercles of the pulmonary veins, especially near the place of
entrance of smaller branches, has been asserted by Mügge,[74] although
appearances similar to those described by him may be met with, due
simply to the agglomeration of white blood-corpuscles and their
necrosis. Such a condition simulates very closely the miliary
tubercle, but is usually analogous to the appearances figured by
Virchow,[75] and described by him as one of the phenomena of
coagulation. In his observation the white bodies were adherent to the
red clots, and were with them drawn from the pulmonary artery.
[Footnote 74: _Virchow's Archiv_, 1879, lxxvi. 243.]
[Footnote 75: _Die Cellular Pathologie_, 4te Auflage, 1871, 184.]
With the admission into the body, and the colonization of the
tubercular bacilli, their effects may either be progressive until the
death of the individual is occasioned, or, with the cessation of the
growth of the bacilli or a possible modification of their noxious
properties, recovery may ensue. The history of scrofulous glands, as
well as that of circumscribed pulmonary inflammation in scrofulous
persons, both presumably of a tuberculous nature, show that the
effects of an invasion of the parasites may be overcome.
The regions of the body which are usually the seat of a primary
tuberculosis are unquestionably the respiratory and intestinal tracts.
With regard to the first of these regions, the one most frequently
affected, there can be no doubt that in most instances the inhaled air
carries the bacilli or their spores, or both. Their constant presence
in the sputum of the frequent cases of tuberculous phthisis suggests a
ready means for their escape into the atmosphere. The well recognized
infective qualities of the sputum, as demonstrated by the various
experiments before the bacillus was discovered, demand the thorough
disinfection of phthisical sputa, since these are in all probability
the chief source of the dissemination of the disease.
The tuberculosis of the intestine in like manner is to be regarded in
the main as the result of an absorption from its surface of the
specific agent. An obvious direct means of the approach of the bacilli
is offered in the sputum, which, when swallowed, is likely to retain
its virulent properties. The frequent coexistence of chronic pulmonary
and intestinal tuberculosis is thus most readily explained. To what
extent the presence of the bacilli in the pearly distemper of cattle
and in the tuberculosis of other edible domesticated animals, as fowls
and swine, may lead to an infection of the intestinal wall, still
remains an unsolved problem. It is not yet determined at what
temperatures the bacilli are destroyed, although their growth takes
place only between 30° C. (86° F.) and {105} 41° C. (105.8° F.). The
inoculation of pearly masses produces tuberculosis in certain animals,
yet the effect of cooking in destroying the bacilli and their spores
is likely to prove of great importance. Aufrecht's[76] attempts at
inoculating rabbits with cooked pearly masses proved unsuccessful.
Schottelius[77] publishes an interesting series of observations
relating to the prolonged use of meat from cattle affected with the
pearly distemper, and shows that after a period of years no disease of
the nature of tuberculosis occurred among the one hundred and thirty
individuals included in the families concerned. Whatever may be the
value of this negative testimony, there is, as yet, no evidence on the
other side which satisfactorily determines the point in question--viz.
that the flesh of animals affected with pearly distemper produces
tuberculosis in the human consumer.
[Footnote 76: _Op. cit._, 51.]
[Footnote 77: _Virchow's Archiv_, 1883, xci. 129.]
The milk from cows thus diseased has likewise been regarded with
suspicion, and the frequency of intestinal tuberculosis among children
has been attributed to this source. Although the theoretical
possibility of the escape of the bacilli into the milk of cows
affected with pearly distemper is obvious, their presence in such milk
is first to be demonstrated under conditions which necessitate their
origin from the animal. If boiling the infective material for three
minutes destroys its virulence, as claimed by Aufrecht, a ready means
is offered of destroying the tubercle bacilli which may be present,
not only in the milk from animals affected with pearly distemper, but
in all milk which has been exposed for a certain time to an atmosphere
which may contain the bacilli of tuberculosis. In the light of our
present knowledge extreme hygienic precautions are only demanded in
those cases where such a congenital or acquired basis (constitution)
is present as facilitates the development of tuberculosis.
Morbid Growths.
In a system of practical medicine it is obviously important to include
under the head of Morbid Growths not only what is spoken of by the
surgeon as a tumor, but also those new formations of tissue which, in
virtue of their nature, seat, manner of growth, and retrograde
changes, produce an important series of disturbances in the
physiological processes of the individual. The surgeon deals
essentially with the swelling, which, producing irregularities in the
outline of the accessible surfaces of the body, is regarded as an
excrescence or outgrowth. It is important for him to realize the
nature of this swelling, that he may follow a different treatment for
the abscess, the wen, the watery accumulation, or the fleshy mass. The
last is the tumor in the limited sense; it is the growth which, though
called morbid, becomes so only in consequence of its presence being
associated with symptoms whose existence and persistence interfere
with the well-being of the possessor.
The physician, on the contrary, is more concerned with the tumor as a
growth than as a swelling. The latter element in deeply-seated
portions of the body may not be brought to his attention. The growth
takes place in such a manner as to be productive of certain symptoms
more or less serious, among which swelling is least obvious. The
morbid {106} growth to him becomes prominent as it displaces or
replaces normal tissues by those newly formed, which may or may not be
normal to the part in which the growth is situated. His tumor is
therefore a morbid growth, a new formation, a neoplasm or pseudoplasm,
rather than a swelling, a bunch, or an excrescence.
In a consideration of the general pathology of morbid growths the
first question which suggests itself relates to the method of origin
of the tumor. The tendency of the present seeks for a local cause, and
the most recent theory, that of Cohnheim, demands an accumulation of
dormant embryonal cells as such a cause. Cohnheim supports this view
by the experiments of Zahn and Leopold, which show that foetal
cartilage transplanted into the tissues of a mature animal may grow so
rapidly as to present the characteristics of a cartilaginous tumor,
while tissues transferred from the animal after birth do not increase
in size, but are usually absorbed.