the traumatic agencies. It includes chemicals whose action is
indirect, through absorption in a diluted form rather than from direct
application in a concentrated condition. Such chemicals are derived
from without, as arsenic, phosphorus, and antimony; or may be formed
within the body, and the latter include the chemical products of
putrefactive changes--in the urine, for instance--and, with
considerable probability, certain of the active agents of
blood-poisoning in septic diseases. It is not unlikely that some of
the inflammatory affections met with among the so-called
constitutional diseases, as rheumatism and gout, may owe their origin
to the production of chemical substances within the body, excessive in
quantity if not changed in quality.
{45} The parasitic causes of inflammation are both animal and
vegetable, and act upon the surfaces of the body or within its
deeply-seated parts. Some of the animal parasites act locally at their
place of entrance, while others produce but slight disturbances in
this region, their effects usually resulting from the transfer of
their offspring to remote parts of the body. The vegetable parasites
are for the most part the various fungi, which act locally upon the
skin or on those transitional surfaces lying between skin and mucous
membrane. The resulting parasitic inflammations are known as favus,
sycosis, ringworm, thrush, etc. The border-line between such parasitic
diseases and those included among the infective diseases is somewhat
arbitrarily drawn. Parasites in the limited sense act chiefly as
foreign bodies, while the effect of minute vegetable organisms is
rather that of ferments, in virtue of their products. Such a
distinction is of relative value merely, as the micrococci and
bacteria are capable of acting in other ways than by the production of
septic material.
The infectious causes of inflammation are for the most part parasitic
in their nature, although the discovery and identification of the
parasite are in most of these inflammations assumed rather than
demonstrated. The relation of the anthrax bacillus to malignant
pustule no longer admits of a doubt, mainly in consequence of the
researches of Koch. This investigator has been enabled to establish a
definite etiological relation between the septicæmia of certain
animals and accompanying minute vegetable organisms. His recent
discovery of the bacillus of tuberculosis definitely removes the
tubercular process from the group of dyscrasic or constitutional
affections to that of the infective diseases. The constant presence of
minute organisms in relapsing fever, leprosy, malaria, typhoid fever,
diphtheria, erysipelas, and numerous other affections associated with,
if not characterized by, inflammatory conditions, renders extremely
probable the closest pathological relation between such diseases and a
microscopic organism. That an inflammatory process may be regarded of
infectious origin, it is necessary, according to Koch,[14] that a
characteristic organism should be found in all cases of the disease,
and in such numbers and distribution as to account for all the
phenomena of the disease in question.
[Footnote 14: _Untersuchungen über die Aetiologie der
Wundinfectionskrankheiten_, 1878, 27.]
These organisms may act in virtue of their growth and the consequent
demand for oxygen, as seems probable in certain cases of malignant
pustule, where the affected individual dies with symptoms of asphyxia.
Their operation may also be like that of ferments, which produce
chemical material whose effect may be remote from the immediate
presence of the minute organism. They may likewise, in connection with
their colonization in various parts of the body, act more immediately
upon the walls of the blood-vessels, and produce that increased
porosity which is so essential a factor in inflammation.
The discovery of the immediate cause of the various infective
diseases, as measles, scarlatina, variola, cholera, dysentery, mumps,
whooping cough, cerebro-spinal meningitis, and numerous other epidemic
and endemic affections, still remains a question for the future. The
constant association of microbia with any or all of such diseases is
but one fact in connection with them, and such a discovery is to be
regarded merely as a step forward, to be followed by others, each of
which represents not only an advance, but confirms the position
attained.
{46} The dyscrasic or constitutional causes of inflammation are those
which, though long established, appear less demanded as our knowledge
advances. Regarded as the result of an alteration in the composition
of the blood, it is obvious that such changes may arise from the
introduction, from without, of wholly foreign material. The dyscrasia
may also represent modifications in the relative proportion of the
normal constituents of the blood. In the former series are included
what, for the most part, have already been referred to under the toxic
and infectious causes of inflammation. The dyscrasiæ from lead,
alcohol, and the like belong to this series. Still more important are
the poisons, the virus of tuberculosis and scrofula, of leprosy and
syphilis. The dyscrasiæ known as anæmia, leucæmia, uræmia, icterus,
and diabetes are to be regarded less as inflammatory causes than as
predisposing conditions which favor the action of other groups of
causes.
The trophic causes of inflammation are those whose action is supposed
to take place through the influence of nerves. Although, as has
already been stated, a faulty innervation of tissues is an important
element in favoring the action of various inflammatory causes, there
remain certain forms of inflammation where the disturbance of nervous
action seems to be the essential feature. The occurrence of an acute
peripheral gangrene soon after certain traumatic or inflammatory
lesions of the brain or spinal cord, of articular inflammation
following chronic affections of the cerebro-spinal axis, are instances
in point. The origin and distribution of herpes zoster, the occurrence
of sympathetic ophthalmia and symmetrical gangrene, suggest a
predominant disturbance of innervation as the exciting cause. At the
same time, it is desirable to call attention to the recent
observations of MacGillavray, Leber, and others,[15] which suggest
that a sympathetic ophthalmia is due to the extension of a septic
choroiditis along the lymph-spaces of the optic nerve. It is further
apparent that in certain so-called trophic inflammations, as the
pneumonia after section of the pneumogastric, and the inflammation of
the eye following paralysis of the trigeminus, the paralysis of the
nerve is a remote, rather than an immediate cause, of the
inflammation. There still remain, however, a number of localized
inflammations whose origin is so intimately connected with nervous
disturbances as to demand, for the present at least, a corresponding
classification.
[Footnote 15: Wadsworth's "Report of Recent Progress in
Ophthalmology," _Boston Medical and Surgical Journal_, 1882, cvi.
517.]
The course of an inflammation is often indicated by the predominance
of certain symptoms, which, for the most part, indicate a condition of
the individual acted upon rather than a peculiarity of the cause. The
sthenic inflammations take place in robust individuals with powerful
hearts and an abundant supply of blood. In such persons a strong
pulse, high fever, and an injection of the superficial blood-vessels
suggested, in former times, the necessity of bloodletting as the
essential therapeutic agent. The sthenic form of inflammation was most
commonly associated with pneumonia, where the obstruction to the
passage of blood through the lungs was an important cause of the
superficial injection of the blood-vessels.
The asthenic inflammations, on the contrary, are those occurring in
feeble individuals, debilitated in consequence of pre-existing
disease, exposure, or habits. A weak heart, low febrile temperature,
and {47} superficial pallor, characterize the asthenic inflammations,
which show a frequent tendency to become localized in the more
dependent parts of the body, the force of the circulation being too
feeble to overcome the effect of gravitation.
In the typhoidal inflammations are associated those symptoms which are
so prominent in the severe varieties of typhoid fever. These are the
predominant symptoms: hebetude or low, muttering delirium, picking at
the bed-clothes, involuntary evacuations, stertor, and the like. The
nervous disturbances are associated with a feeble pulse and a dusky
hue of the skin.
The constituents of an inflammatory exudation are frequently used as a
basis of classification, and characterize the inflammation from the
anatomical point of view. As the exudation is complex in its
composition, the predominant element is made use of to designate the
variety, and in doubtful cases a combined adjective indicates the
presence of the two most abundant constituents. As the exudation is
directly derived from the blood and contains serum in addition to
white and red corpuscles, the serous, purulent, and hemorrhagic
varieties of exudation naturally arise. The fibrinous and diphtheritic
inflammations relate to the presence of membranes or false membranes.
Finally, there are the productive inflammations, resulting in the new
formation of tissue, and the destructive inflammations, where losses
of substance occur.
Serous inflammations are most frequent in those parts of the body
where the structure contains the largest lymph-spaces. The so-called
serous cavities of the body offer the most favorable opportunities for
the accumulation, as well as for the exudation, of the inflammatory
product; then follow the regions of the larger lymph-spaces, according
to the size and number of the latter.
The serous inflammations may also arise from the epithelial coverings
of the body, as the cutaneous, alimentary, and respiratory surfaces.
The serous exudations of the skin are those present in vesicles,
blisters, or bullæ, which owe their limitation to the resistance
offered to the spreading of the liquid inflammatory product by the
coherent epidermis. Serous inflammations of the alimentary canal may
assume a vesicular character, although, from the structure of its
mucous membrane and the macerating influence of its contents, the
vesicles are apt to be of an extremely transitory character.
The more important serous inflammations of the intestines are those
manifested by profuse watery evacuations, the extreme form of which is
to be found in cholera.
Serous inflammation of the lungs accompanies the more severe forms,
and usually represents but a limited and circumscribed affection,
associated with more abundant cellular and fibrinous products.
Serous inflammations of the peritoneum, pleura, pericardium, tunica
vaginalis, and central ventricles often give rise to the presence of
enormous quantities of fluid, whose partial removal from many of the
cavities concerned by operative measures frequently represents a most
beneficial result of treatment.
The smaller lymph-spaces of the connective tissue in various parts of
the body are the frequent seat of the inflammatory oedema, so called,
whose presence is an important indication of the direction assumed by
a {48} spreading inflammation, as well as a suggestion of the frequent
virulence of its cause.
In general, the serous inflammations are to be regarded as less severe
than other varieties, or as representing an early stage of what later
may be otherwise characterized by a change in the nature of the
products.
The purulent variety of inflammation is present when the exudation is
abundantly cellular. As has already been stated, such cells are, for
the most part, white blood-corpuscles. The purulent exudation, like
the serous variety, may appear either on surfaces, when the term
secretion is applied, or within the lymph-spaces of the connective
tissue over a considerable space, when the pus is said to be
infiltrated. When the infiltration is more circumscribed and the walls
of the affected lymph-spaces are destroyed, so that adjoining cavities
are thrown into larger holes, an abscess is present, from whose wall
pus is constantly derived, while the inflammation is progressive.
The attention of the surgeon, in particular, has been directed to the
isolation of the immediate cause of suppurative inflammation, and the
modern, antiseptic, treatment of wounds is essentially based upon the
view of the infectious origin of pus. The frequent presence of
microbia in purulent exudation where no precautions are taken to
exclude their admission, and their frequent absence or presence in
minute quantities where such precautions are taken, have suggested
that through their influence an inflammatory exudation is likely, if
not actually compelled, to become purulent.
Whether the microbia or their products are the cause of most
suppurative inflammations may be regarded as an open question. It is
generally admitted, however, that, as a rule, an inflammation becomes
purulent in consequence of the presence of an infective agent; in
other words, that most pus is of an infectious origin and possesses
infectious attributes. The labors of Lister in insisting upon the
exclusion of all possible putrefactive agencies in the treatment of
wounds have met with universal approval, and the basis of his
treatment remains fixed, although different methods have been devised
for its enforcement. His researches, and those stimulated by his work,
have resulted in the establishment of principles which affect the
whole field of theoretical as well as practical medicine.
Although most pus may be considered as due to the action of a virus
introduced from without, and capable of indefinite progressive
increase within the body, all pus is not to be regarded as of
infectious origin. There are pyrogenetic agencies, like petroleum,
turpentine, and croton oil, which, introduced into the body, produce
suppurative inflammation without the association of microbia.
A bland pus is usually in a state of beginning putrescence, so that it
is only relatively bland, and acquires extreme virulence when long
exposed to putrefactive agencies. It is possible that those agencies
producing an ichorous pus are the same or different from those present
in bland pus. The ichorous exudation contains less corpuscles than
bland pus, is more fluid, less opaque, strongly alkaline, of a
greenish color, and of offensive odor.
In hemorrhagic inflammation the exudation contains large numbers of
red blood-corpuscles. The occurrence of this form is sometimes
associated {49} with peculiarities of the cause, as is obvious from
the epidemics of hemorrhagic small-pox, measles, scarlatina, and
cerebro-spinal meningitis. It is also associated with peculiarities of
the individual, as in such epidemics all cases are not equally
hemorrhagic, and in scurvy the hemorrhages are attributable to the
abnormal conditions to which the sufferers are exposed. Hemorrhagic
exudations are also met with in those inflammations of serous surfaces
accompanying the outcropping of tubercular and cancerous or
sarcomatous growths. In all cases a hemorrhagic exudation represents a
grave complication, and when found in serous cavities has a certain
diagnostic, as well as prognostic, importance.
Fibrinous inflammations are characterized by the presence in the
exudation of considerable quantities of fibrin. As the prevailing
theory of the formation of fibrin demands fibrino-plastic as well as
fibrinogenous material, both are to be sought for in the exudation.
The latter is present in the liquid portion of the exudation; the
existence of the former, as well as that of the ferment, is dependent
upon the presence of the white blood-corpuscles. The more numerous
these, within certain limits, the more abundant the formation of
fibrin. As their death appears essential for the fibrinous
coagulation, the latter is most constantly met with in those parts of
the body where the white blood-corpuscles are quickest separated from
influences favoring their life. The farther removed they are from the
blood-vessels, the more likely is their early death. Fibrinous
exudations are therefore frequent and abundant in cellular and serous
(sero-cellular) inflammation of the great serous cavities of the body.
The clotted fibrin appears as false membrane lying upon the serous
surface, either smooth or rough, tripe-like, or as villosities
projecting above the surface, and again as bands, fibrinous adhesions,
stretching across the cavity and uniting opposed surfaces.
The frequent occurrence of fibrinous exudations on the mucous
membranes of the larynx and trachea, accompanied by the suffocative
symptoms known as croup, has led to the use of the term croupous
inflammation as synonymous with fibrinous inflammation, and its
application to various parts of the body where croupous--_i.e._
suffocative--symptoms are not in question. Croupous inflammation, when
used, is to be considered as an anatomical term, indicating merely the
production of fibrin, and, for the avoidance of confusion, it is
preferable to substitute fibrinous for croupous when such
inflammations are described.
The disease, croup, it is well known, may exist without a
croupous--that is, fibrinous--inflammation, as is familiarly
recognized in the constant use of the terms spasmodic, membranous, and
diphtheritic croup.
Fibrinous inflammation of the mucous membrane of the larger
air-passages is much more frequently met with than that of mucous
membranes elsewhere, as of the intestines, uterus, and bladder. The
pseudo-membranous inflammations of the latter tracts are more commonly
the result of the catarrhal and diphtheritic varieties than of the
fibrinous form. Fibrinous exudations on mucous surfaces, according to
Weigert, can only take place when the epithelium is destroyed. Hence
those causes which give rise to the destruction or detachment of the
epithelium are alone capable of producing a fibrinous inflammation of
mucous membranes, and a fibrinous laryngitis, trachitis, and
bronchitis may result from {50} the local application of such
irritants as steam or ammonia, as well as occur in the diseases croup
and diphtheria.
Fibrinous exudations may also be present within tissues, especially in
those whose meshes are wide, provided the essential elements of
coagulation are present. The coagulative necrosis of various organs,
to be more fully mentioned hereafter, is closely allied to fibrinous
clotting, the fibrino-plastic element being derived from the death of
the parenchymatous cells of the part.
In the existence of a fibrinous pneumonia the conditions are somewhat
analogous to those present in the fibrinous inflammation of serous
surfaces and of the areolar connective tissue. There is present an
abundantly cellular exudation, held in the place of its origin, the
cells undergoing rapid death and surrounded by a wall whose
superficial cells resemble in structure, if not in origin, the
endothelial cells lining the smaller lymph-spaces of connective
tissue, as well as the larger cavities within the same, known as
serous cavities.
The diphtheritic inflammation is no more to be confounded with the
disease diphtheria than is the fibrinous inflammation with the disease
croup. Although diphtheria owes its name to the frequent presence of
an apparent membrane, it may be said that the latter is not essential
to the existence of the former. Diphtheria, like croup, is an
affection in which various exudations may be present, and the
anatomical product alone does not suffice in all instances for the
recognition of the disease. In croup there may be a swollen mucous
membrane, with a slight superficial mucous exudation, or a more
abundant exudation of desquamated epithelium and mucus, as well as a
fibrinous false membrane. In diphtheria the same varieties of
exudation may occur, and in addition the diphtheritic exudation may
also be present. The latter, however, is not limited to the disease
diphtheria, for its presence is apparent in other mucous membranes
than that of the air-passages, and in the pharyngeal mucous membrane
in other diseases than diphtheria. A diphtheritic conjunctivitis,
enteritis, cystitis, and endometritis are recognized. The cutaneous
surfaces of the body may also furnish a diphtheritic exudation. The
diphtheritic inflammations of wounds and of variolous eruptions are
instances in point.
The characteristics of a diphtheritic inflammation are the presence
within the tissues of a clotted exudation, which is associated with a
defined swelling and death of the part. The exudation contains not
only dead leucocytes and interlacing fibres, but is also provided with
abundant granular material, much of which presents the well-known
peculiarities of microscopic organisms. The apparent false membrane is
thus dead, infiltrated tissue, which may be torn away from the
continuous unaffected tissue, leaving a raw, rough surface, but not
peeled from a comparatively smooth surface, as in other forms of
pseudo-membranous inflammation.
The frequent association of a superficial false membrane,
corresponding in area with that of the deeper-seated changes, in which
cells and fibres may be present, is to be recognized. The diphtheritic
process, however, is localized within, and not upon, the tissues
affected. The diphtheritic exudation represents a local death, a
necrosis, of the part concerned, and the result has frequently been
compared with the death consequent upon the action of a caustic.
{51} The immediate cause of a diphtheritic inflammation is now
generally attributed to the action of microbia which enter the tissue
from without, and in their growth beneath the surface produce not only
the local, but also the remote, constitutional disturbances which are
associated with a diphtheritic inflammation. The investigations of
Wood and Formad[16] point to ordinary putrefactive organisms as a
sufficient cause for the diphtheritic inflammation of diphtheria,
while other observers demand a specific organism as the exciting
cause. The occurrence of diphtheritic inflammations in various parts
of the body, in regions, as the intestine, where putrefactive
processes are constantly present, and in the bladder and uterus, where
the phenomena of putrefaction are often associated with diphtheritic
inflammation, suggest the efficacy of ordinary putrefactive agencies
in producing the latter. As all microbia found in putrefaction are not
alike, and as the properties of certain, differ from those of others,
and as our knowledge of the effects of all is but fragmentary, the
characteristics of specific germs for a diphtheritic inflammation of
one part of the body, or of all parts of the same, must still be
regarded as not proven.
[Footnote 16: _Research on Diphtheria for the National Board of
Health_, 1880, Supplement No. 7.]
Productive inflammations are those which result in the new formation
of tissues. One of the frequent products of inflammation is fibrous
tissue, which, at first abundantly cellular, later becomes more
vascular, and is finally transformed into a tissue whose fibres
predominate over its cells. This formation of a cicatricial tissue
demands further recognition when the termination of inflammation is
considered.