Studies in the Osteopathic
Cells of the Blood: Volume
Louisa Burns, M.S., D.O., D.Sc.O.
THE BLOOD PLASMA, PLATELETS AND FIBRIN
The fluid part of the blood is not less important
than the cells which are carried therein. The constituents of the
plasma change constantly, as the constituents of living cells change constantly,
and, like living cells, the blood plasma maintains always a fairly uniform
chemical structure. This uniformity is not, apparently, maintained
by any vital activity of the plasma itself. The tissues which are
bathed by the fluids derived from the plasma vary their activities according
to varying plasma conditions, and the result of such variations in the
physiological activities of normal tissue cells is the maintenance of a
chemical and physical equilibrium of blood plasma, tissue fluids and lymph.
So long as the circulation of the blood remains normal, and the various
tissues of the body not too badly injured, the blood plasma and the fluid
derived from it retain at nearly the same level of water-content, chemical
structure and osmotic tension. The various salts and organic substances
vary slightly according to varying diet, exercise and other physiological
conditions but even these variations are only slight and transitory, so
long as the circulation of the blood is normal and the tissues reasonably
normal in structure.
The blood plasma serves as a method of transportation.
The waste products of katabolism are removed by the blood plasma and are
carried to the various emunctories to be eliminated from the body.
Katabolites which can be utilized again are carried in the plasma to the
tissues which need them. Hormones are katabolites of one tissue which serve
a useful purpose in some other tissue; they are carried in the blood plasma
from the places of their manufacture to the places of their functional
activity. Various gases are transported in solution by the plasma.
Food materials are carried from the intestinal tract to the liver and other
tissues, to be elaborated into the compounds required by the living cells
of the body, and from these various organs to the tissues which need food.
The blood cells themselves are fed by the plasma
and they give off katabolites to the plasma. The plasma transports
the newly formed blood cells from their sites of origin in the bone marrow
and the lymphoid tissues over the entire body; the plasma feeds them through
their lives within the blood stream, the plasma receives their dead bodies
and disposes of them.
The plasma is a medium of communication between distant
tissues, by means of the hormones and enzymes which it carries and by the
manner in which it is affected by varying physiological states. For
example, if the blood plasma carries an excess of carbon dioxide certain
groups of nerve cells are thereby so affected that they cause increased
respiratory activity. Many such reactions occur constantly and the
entire body is enabled to act as a unit because the circulating blood plasma
as well as the delicate nervous tissues maintain always these systems of
inter-communication between distant tissues.
The varying states of the blood plasma are best studied
by means of the changes which occur in the blood cells, and by chemical
analysis of the bloods. The latter subject is beyond the scope of
this book. The changes which occur in the blood cells as a result
of changes in the circulating plasma is a matter of much interest.
TOTAL PLASMA VOLUME
The importance of determining the total plasma or
blood volume is evident, yet at this time there is no known method which
is sufficiently accurate and simple to be used in ordinary circumstances.
In hospitals with a large and efficient laboratory staff it is possible
to determine the total blood volume with reasonable accuracy. From
published reports of work in this field it is now known that the total
blood plasma per unit of body weight or body surface varies only moderately
in nearly all diseases, and that so far as practical clinical experience
is concerned the studies made of any given amount of blood are sufficiently
accurate for diagnosis in most cases.
Much work has been done in an attempt to determine
the normal amount of the blood in the entire body.
Welcher’s findings were based upon a study of decapitated
criminals. The blood was received into vessels, and the veins were
then washed out with water. The hemoglobin was determined for the
fresh blood and also for the washings mixed with blood. He estimated
the total blood weight as 7.7% and 7.2% of the body weight for two different
Haldane and Smith allowed the patient to inhale a
measured amount of carbon monoxide and after a time the amount of carbon
monoxide hemoglobin was determined. This method gives figures approximately
identical with those secured by the vital red method.
The best method now known for the determination of
the total amount of blood in the human body is that employed by Rowntree
and his associates of the Mayo Clinic. It consists, briefly, of the
injection of a known amount of some harmless dye into one cephalic vein,
then the withdrawal of a known amount of blood from the opposite cephalic
vein three or six minutes later. The total amount of blood in the
body can be estimated from the dye present in the withdrawn blood.
According to Denny and also to Bock the plasma volume
of the blood remains at a definite level per unit of body weight in nearly
all normal and abnormal conditions except in those associated with severe
dessication of all the tissues. Changes in the total blood volume
are due to changes in the corpuscle volume. Blood volume is increased
during pregnancy but returns to normal within about a week after delivery.
Blood volume is increased in certain anemias; the increase is in the plasma
alone. Increased blood volume occurs in chlorosis, polycythemias
and a few other diseases. Decreased blood volume occurs in dessication,
after very severe hemorrhages and after severe diarrheas and severe sweating.
The total blood volume remains remarkably constant
under varying physiological conditions.
Rowntree advises the use of the terms normovolemia,
hypovolemia and hypervolemia to express a normal relation between blood
volume and body weight, abnormally low blood volume per kilo of body weight
and abnormally high blood volume per kilo of body weight. When the
blood cells are relatively increased the condition is called polycythemic
normovolemia, polycythemic hypovolemia or polycythemic hypervolemia, according
to the increase in cells in blood of normal volume (relative to body weight),
or in blood of diminished or increased volume. Similarly, when the
cells are relatively low and the serum relatively high the condition is
called oligocythemic normovolemia, oligocythemic hypovolemia or oligocythemic
hypervolemia according as the diminished cell count occurs in blood of
normal, increased or decreased volume per body weight.
NORMAL VOLUME RELATIONS
Rowntree has taken the figures which he has derived
from an average of normals as a criterion; for blood, 87.7 cubic centimeters
per kilogram of body weight; for plasma 51.2 cubi centimeters per
kilogram of body weight; for blood cells, 36.5 cubic centimeters per kilogram
of body weight. This means that approximately one-eleventh of the
body weight of normal individuals is composed of blood. Findings
for normal persons vary by 10% or more from these figures, just as some
perfectly normal persons may have a basal metabolism rate of 10%
more or less than 40 calories per hour per square meter, or a temperature
slightly above or below 98.6 degrees F. or a red blood cell count of four
million or of five and one-half million, per cubic millimeter, and so for
every other condition in which a definite normal figure is generally accepted.
ABNORMAL BLOOD VOLUME
Under several abnormal conditions Rowntree found
significant variations in plasma volume and in blood volume.
In obesity without edema the amount of blood in the
body is considerably increased, while the amount of blood per unit of body
weight or per unit of body surface is considerably diminished.
In pernicious anemia the blood volume per unit of
body weight or body surface is diminished. In secondary anemias the
blood volume may be increased, decreased or unchanged, according to the
causes of the anemias.
In polycythemia vera the total volume of blood is
increased both actually and per unit of body weight and body surface.
In secondary erythrocytosis the total blood volume remains almost or quite
In edematous states there is little or no variation
in the blood volume except in glomerulonephritis. In this renal disease
the total blood volume may not be affected, and if it is affected at all
it may be increased or diminished. Cardiac edema shows no significant
changes in the total blood volume.
In Banti’s disease and in splenomegaly without anemia,
with or without cirrhosis of the liver, the blood volume is somewhat increased.
In all forms of leukemia the total blood volume is increased considerably.
Hypertension is associated with a normal blood volume per unit of body
surface and body weight.
ALKALINITY OF THE BLOOD
The blood has feeble alkalinity due to the presence
of alkaline carbonates and alkaline phosphates. These bases are in
feeble combination with the blood proteins, including hemoglobin, under
ordinary conditions. With increasing carbon dioxide content the bases
are set free, combine with the carbon dioxide and the essential neutrality
of the blood is preserved. The presence of these bases in this loose
chemical combination provides the “buffer action” which is of such great
importance in maintaining the power of the blood to carry oxygen and carbon
dioxide to and from the active tissues of the body. The alkalinity
of the blood is commonly measured in terms of its ability to carry carbon
dioxide, and variations in the carton-dioxide-combining-power of the plasma
are identical with variations in the alkalinity of the blood.
The average reaction of the blood of a healthy young
man, at rest, as reported from several laboratories, is as follows:
blood plasma . . . . . . .pH 7.443
Arterial blood cells . . . . . . . . .pH
Venous blood plasma . . . . . . .pH 7.416
Venous blood cells . . . . . . . . .pH 7.134
The average reaction of the blood of a healthy young
man, after vigorous exercise lasting for about an hour, is as follows:
blood plasma . . . . . . .pH 7.375
Arterial blood cells . . . . . . . . .pH
Venous blood plasma . . . . . . .pH 7.277
Venous blood cells . . . . . . . . .pH 7.026
The alkalinity of the average young healthy woman
is somewhat lower, the variation being in harmony with the lower hemoglobin
and the lower specific gravity of the blood of women. These variations
are not primarily sex characteristics. Women who live active lives
show the specific gravity, cell count, hemoglobin content and alkalinity
characteristic of the blood of men who live active lives, and men who live
sedentary lives show the specific gravity, hemoglobin content, cell count
and alkalinity characteristic of the blood of women who live sedentary
lives. Since more women than men are inactive, and more men than
women live active lives, the proportions given as characteristic of the
sex variations in blood are fairly accurate, so far as averages are concerned.
It must always be remembered, however, in making blood examinations for
women who are athletic, and for men who live quiet and inactive lives,
that figures normal for the habits of the patient must be taken as normal
without regard to sex.
The alkalinity of the blood varies slightly and temporarily
as a result of many physiological conditions. Increase in the
amount of carbon dioxide of the blood results in increased respiratory
activity, the elimination of the carbon dioxide and return to normal resting
alkalinity. Increased intake of alkaline substances results in the
elimination of the excess, chiefly by the kidneys.
Changes in the alkalinity of the blood as a result
of disease may be considerable. In diabetic coma there are several
organic acids present in the blood plasma. Henderson gives the following
figures for a patient in diabetic coma:
blood serum . . . . . . . . pH 7.140
Arterial blood cells . . . . . . . . . pH 7.075
Venous blood serum . . . . . . . . pH 7.028
Venous blood cells . . . . . . . . . pH 6.955
The alkalinity of the blood is diminished in all
diseases in which the aeration or the circulation of the blood is impeded,
as in pulmonary tuberculosis, pneumonia, endocarditis and other cardiac
diseases. The alkalinity of the blood is also diminished in renal
disease. Henderson gives the following figures for a moribund nephritic:
blood serum . . . . . . . . pH 6.994
Arterial blood cells . . . . . . . . . pH 6.987
Venous blood serum . . . . . . . . pH 6.969
Venous blood cells . . . . . . . . . pH 6.970
The fact that so little difference exists between
venous and arterial blood cells and blood serum is of interest in this
The alkalinity of the blood is increased by increased
atmospheric pressure. Menten gives the following figures:
pressure . . . . . . . . . . . . . mm
Reaction venous blood serum . . . . . . . .
Atmospheric pressure . . . . . . . . . . . . . mm
Reaction venous blood serum . . . . . . . . . . .
Menten’s figures are, for normals . . . . . . . .
Menten gives also the following figures for abnormal
(60 cases) . . . . . . . . . . . . . .
Malignancy ( 5 cases) . . . . . . . . . . . . . . .
Active syphilis . . . . . . . . . . . . . . . . . . . .
Henderson gives the following figures for a patient
blood serum . . . . . . . . . . . . . . . .
Arterial blood cells . . . . . . . . . . . . . . . . .
Venous blood serum . . . . . . . . . . . . . . . .
Venous blood cells . . . . . . . . . . . . . . . . .
Henderson gives for a patient with pernicious anemia:
blood serum . . . . . . . . . . . . . . . .
Arterial blood cells . . . . . . . . . . . . . . . . .
Venous blood serum . . . . . . . . . . . . . . . .
Venous blood cells . . . . . . . . . . . . . . . . .
Accurate determinations of the reaction of the blood
can be made by means of a potentiometer or a voltmeter. These methods
do not require an unreasonable amount of blood. Determination of
the carbon-dioxide combining power of the blood serum gives results of
practical value but this method requires rather more blood than it may
be advisable to remove from the veins of a very sick person.
Methods based upon the use of reagents are much less
accurate but they may give results of clinical value under certain circumstances.
The effects produced upon the cells of the blood
by variations in the reaction of the blood plasma are of considerable interest.
In acidosis due to the presence of abnormal acid
substances in the blood stream, such as may be found in diabetes mellitus,
the cells show no marked variations in their staining reactions.
In acidosis due to renal disease differential staining
is difficult because the chemical differences between nucleus and protoplasm,
and between the hyaloplasm, deutoplasm and granuloplasm of the dells are
less marked than in normal blood. In slides stained with eosin and
methylene blue the nuclei take a dull, grayish blue, the neutrophilic granules
a grayish lavender, the eosinophiles show a dull, bluish hyaloplasm with
grayish, pink granules, the hyaline cells show a dull, bluish protoplasm
in which irregularities of staining often cause a semblance of granulation.
The various structural changes in the cells due to disturbances in protein
katabolism are usually present also.
In acidosis due to circulatory disturbances, such
as are found when cardiac inefficiency supervenes in other diseases, the
changes in staining are similar but are usually less marked. In addition
there is considerable gregariousness of the cells, and the neutrophiles
and the monocytes show marked irregularities in contour; often they have
their edges quite ragged and grayed. Concentration of the cells of
the peripheral blood, with red and white cells counts considerably above
that normal to the individual are also usually conspicuous factors in the
acidosis due to cardiac inefficiency.
In the blood of persons with alkalosis the cells
show increased avidity for differential stains. In slides stained
with eosin and methylene blue the nuclei are a very vivid and brilliant
blue. The hyaline cells also show unusual brilliance of staining
and they frequently contain azur granules of large size and a royal purplish
blue. The neutrophiles are definitely lavender in hue and the eosinophiles
shine with even more than their normal brilliance. All the cells
of the blood are a trifle smaller than in normal blood and the red cells
crenate very quickly on the warm slide.
These variations are recognizable only if the methods
employed in studying different specimens is uniform, and if the stains
can be varied to meet varying conditions of the blood cells. If the
conditions usually associated with acidosis are found, the stain should
have a crystal or two or three of sodium bicarbonate added to the solution.
This should show an approach to normal staining if acidosis is really present.
If the conditions characteristic of alkalosis appear,
a stream of carbon dioxide should be passed through the stain before it
is used, or a drop of weak acetic acid may be added to the stain.
This should cause the cells to swell slightly and to give more nearly normal
staining reactions, if the cause of the staining peculiarities is really
PIGMENTS OF THE BLOOD PLASMA
Variations in the color of the plasma or of the
serum are often noted in pathological blood. Normally the blood plasma
and the serum alike present a rather pale straw color due to the presence
of urobilin and other bile derivatives. Abnormally several other
pigments are present and these may be of importance in diagnosis under
certain conditions. Incorrect readings of hemoglobin may be made
as a result of discoloration of the plasma in severe cases of cholemia
Hemoglobin and its derivatives may tint the plasma
under those conditions which disintegrate the erythrocytes. Malaria
is a common cause of hemoglobinemia; the malarial parasite causes fragmentation
and stroma injury of the red cells and laking occurs easily. The
hemoglobin is finally excreted in the urine and the bile. The pigment
within the parasite is probably a derivative of hemoglobin. The death
of the parasite sets this free in the plasma. The kidneys and the
liver finally eliminate it from the body. The leucocytes and the
cells of the reticulo-endothelial system ingest the fragments of erythrocytes
which have been ruined by the malarial parasite, and the iron-free moiety
of hemoglobin is finally transformed into bilirubin or some related pigment.
This pigment also is set free in the plasma. As a result of these
various reactions the plasma often becomes definitely tinged in cases of
Hemoglobin may be set free from the erythrocyte stroma
by several other conditions. Saponins and certain other glucosides,
several types of venom, certain bacterial products and the bile salts all
have the property of laking the blood. Excess of heat and cold, especially
alternating heat and cold, may also cause laking. This may occur,
though rarely after severe frost-bites and after some part of the body
has been frozen. Hemolytic streptococci may cause very severe anemia
which is associated with a dark-colored blood plasma. Infection by
the blastomycetes hemolytica causes hemoglobinemia like that produced by
malaria; both conditions being due to the fragmentation of the erythrocytes
by the organism and the ultimate laking of the fragments with destruction
of the hemoglobin. (Plate IX)
CARBON MONOXIDE POISONING
The blood of patients with chronic mild carbon monoxide
poisoning shows some traces of methemoglobin derived from the carbon monoxide
hemoglobin of the erythrocytes injured by the gas. The erythrocytes
whose hemoglobin has been combined with caarbo monoxide remain for a time
in the circulation but are finally destroyed. The pigment derived
from these blood cells includes methemoglobin and some r elated compounds
which tinge the plasma a peculiar brownish color. Such plasma does
not give a reaction for bile pigments by any of the usual tests.
Persons with lesions of the lower thoracic vertebrae
and the related ribs suffer somewhat from renal and hepatic disturbances,
and such persons are often unable to eliminate the coloring matter of vegetables
adequately. These persons are usually somewhat emaciated and anemic,
quite nervous and irritable and show other symptoms of mild, chronic toxemia.
Unfortunately a diet rich in the colored vegetables is often advised for
such patients. Being unable to eliminate the carotin speedily this
pigment accumulates in the blood plasma. The plasma and also the
serum in such cases presents a peculiar greenish tint which is quite distinctive,
and it does not give any reaction for the bile pigments.
Carotinemia is not an uncommon condition in those
countries in which colored vegetables are freely eaten. In order
to correct the condition it is necessary that the patient should eat only
colorless vegetables until the blood plasma has returned to its normal
color and the symptoms of toxemia have disappeared. Unless the patient
receives adequate osteopathic treatments he must always refrain from eating
more than a small amount of colored vegetables.
Mr. P. C. This patient was a young man with
early pulmonary tuberculosis. He had been advised to go to Southern
California and to live largely on vegetables. He earned his living
by working in a small roadside lunch room. Being persuaded of the
great value of spinach and other colored vegetables as blood-building materials
he ate spinach three times each day, and ate other colored vegetables and
fruits freely. He ate no cereals or starchy vegetables, no meat,
eggs, milk or milk products.
The lesions usually present in tubercular subjects
were found on osteopathic examination. The blood cell examination
showed moderate secondary anemia and the usual evidences of milk toxemia
and malnutrition. There was also a greenish tint of the blood serum.
The serum did not give any of the ordinary reactions for bile pigments.
For three weeks no osteopathic treatments were given,
in order that the dietetic condition might be tested. Mr. P.
C. was given a balanced diet which included all good wholesome foods except
colored vegetables or fruits. He was permitted a reasonable amount
of colorless vegetables and fruits. As a result of this diet alone
the symptoms of vegetables and fruits. As a result of this diet alone
the symptoms of toxemia and malnutrition diminished, the blood serum regained
its normal color and the general condition improved. Some malnutrition
and toxemia persisted, and the symptoms of tuberculosis showed no changes.
After the carotinemia had disappeared the usual osteopathic treatment for
the vertebral lesions was given and ultimately Mr. P. C. recovered.
Blood platelets, or “third corpuscles” are small
masses of protoplasms found in the blood stream. They vary in size
with an average diameter of three microns. They have no recognizable
cell membrane and no true nucleus, though the center of the mass often
takes nuclear stains in a feeble and atypical manner. They are of
varying forms, being roundish, oval, rod-like or spindle-shaped.
They disappear very quickly after the blood has been drawn and special
methods of technique must be employed in order to count them. A few
are still visible in nearly every smear preparation. They have a
peculiar sticky consistency and they adhere to glassware very closely.
They are concerned in the coagulation of the blood.
THEORIES OF ORIGIN
Views concerning the origin of the platelets are
interesting. Engel, Maximow, Preisch and others considered them the
extruded nuclei or remnants of the degenerated nuclei of the normoblasts.
Hayem thought them immature red cells. Wlassow considered them fragments
broken from red cells. Schultze believed them to be fragments of
broken down leucocytes. Lowit denied their actual existence and thought
them merely artifacts. Bizzozero, Osler and Deetjen considered them
truly cells, in the sense that the erythroytes are cells. Cole found
that certain agglutinins which affect the platelets do not affect the red
blood cells. Kemp found evidences of hemoglobin in the platelets.
Marchesini considered erythrocytes grouped into three classes, stable,
partly stable and unstable. Platelets are formed from fragments of
the third class. De Govaerts and several others described bacteria
found within platelets, and supposed this form of phagocytosis of bacteria
and other foreign objects to be a factor in immunity. It is now thought
that reports of this kind rest upon the presence of fragments of white
cells containing bacteria, and that these have been mistaken for platelets.
By means of more recent methods of staining, such fragments can be differentiated
from platelets, and this source of error eliminated.
Platelets arrange themselves in groups in shed blood
and these groups may be the center from which radiating threads of fibrin
arise. Disintegration occurs rather rapidly unless some methods of
preserving them has been employed and during the process of degeneration
various peculiar appearances occur, these have been called “mucoid degeneration”
and “viscous metamorphosis;” various other terms have been applied to pseudo-structures
produced during the degeneration of the platelets.
The platelets are now known to be formed by budding
from the protoplasm of the megakaaryocytes in the red bone marrow.
Other sources have been described; none has been definitely proved, but
there may be several other methods of development of platelets than from
the megakaryocytes. The platelets in mammalian blood are analogous
to the thrombocytes in the blood of birds and reptiles.
The normal number of platelets seems to vary between
rather wide limits at different times of day for the same person, and for
different normal individuals. The normal number of platelets in normal
human adult blood has been estimated at from 200,000 to 350,000 per cubic
millimeter with variations of 50,000 in either direction for the same person
at different times.
They are physiologically low in the new-born and
in senility. The blood of animals which live in darkness and of young
born of such animals is low in platelets Persons whose diet contains
little or no vitamin A, and animals kept without vitamin A have low platelet
count. In such cases the platelets can be increased by exposure to
sunshine or, less efficiently, to radiations from a mercury lamp.
Increase of the foods containing vitamin A facilitates the return of the
platelets to normal, though these foods are less efficient without sunshine.
The sunshine seems to affect the development of platelets from tissues
of the body, since platelets are increased during starvation if the animal,
previously bred and maintained in darkness, is placed in sunny quarters.
They are greatly increased after hemorrhages whether these are due to accident
or to the effects of disease.
They are increased in all secondary anemias, in chlorosis
and in some cases of myelogenous leukemia. They are diminished in
typhoid fever, idiopathic purpura , aplastic anemia, pernicious anemia,
lymphatic leukemia, and in almost any very severe anemia with inefficient
regeneration of blood. In sudden acute fevers the platelets first
diminish, then increase; the changes parallel the changes in the leucocyte
count. In acute fevers of somewhat longer course the platelets do
not follow the leucocyte changes but diminish during the early weeks, then
increase as the strength of the patient diminishes. Rapid decrease
of platelets is of ominous significance during the course of the slower
acute fevers, especially typhoid fever.
In most cases of acute, severe, high pyrexia the
platelets are very low; in severe pneumonia and in severe malaria it may
be difficult to find any platelets at all, even by the most careful methods.
After crisis in pneumoia, and after sudden decrease in any fever, the platelets
may suddenly rise far above normal, and then within a few days return to
normal numbers. In erysipelas, septicemia and acute articular rheumatism,
however, the platelets are considerably increased.
Platelets are diminished in the circulating blood
during the formation of a thrombus; this fact may be useful in the diagnosis
of thrombosis in the early stages. In one case of ours the diagnosis
made upon this fact, in a case of doubtful nervous disease, was quite important.
The platelets remain unchanged in most hemorrhagic
diseases, and in most other forms of secondary anemia the platelets are
considerably increased. This fact is sometimes useful in diagnosis.
FATE OF BLOOD PLATELETS
These particles of protoplasm seem to undergo dissolution
in the circulating plasma, and probably serve as food materials for various
tissues. The spleen and other areas of the reticulo-endothelial system,
and the monocytes of the circulating blood all ingest and destroy them.
Their length of life has not been well studied.
Probably they live only a few days at most. Indeed the term “life”
is scarcely applicable to their feeble activities of the time of their
THE FIBRIN RELATIONS OF BLOOD
The relations of the fibrinogen of the blood, the
phenomena of clotting and the mechanisms by means of which the blood is
maintained in a fluid state under ordinary conditions present a group of
The functional value of coagulation is evident.
Upon even a slight injury to the blood vessels the blood coagulates and
thus plugs the bleeding vessels. The formation of a coagulum in wounded
areas serves several useful purposes. The injured cells are cemented
together and held in place. The peripheral layer of adult cell protoplasm
is subjected to the tension normally present in embryonic cells and the
pressure thus exerted upon the cell contents initiates cell division, thus
leading to replacement of the cells destroyed by the injury. Further
bleeding is prevented and conditions adapted to rapid repair of the wound
are presented. The repair of wounds by first intention is often surprisingly
rapid and this is due to the fact that the coagulum provides these necessary
conditions for the recovery of injured cells and the replacement of destroyed
THEORIES OF COAGULATION
The mechanism of coagulation has been studied carefully
by many workers but the problems are not yet solved in any satisfactory
manner. It seems fairly well demonstrated that coagulation of the
blood can occur only when there are present fibrinogen, platelets, calcium
salts and extract derived from injured cells, either of the blood itself
or of their tissues. The relations between these factors and the
steps by which each substance reaches the final clot have been variously
described by different students.
Howell’s theory is the basis upon which more recent
investigators have developed many ingenious descriptions. According
to Howell, normal circulating blood contains fibrinogen, prothrombin, alcium
salts and anti-thrombin. The function of the last named substance
is to hold the prothrombin in combination and to prevent the formation
of thrombin within the blood vessels. When blood escapes from the
vessels, or when certain abnormal conditions occur within the vessels,
the platelets disintegrate and thromboplastin is set free; this combines
with the antithrombin, which in turn sets free the prothrombin. The
prothrombin becomes thrombin in the presence of calcium salts; this acts
upon the fibrinogen and transforms it into fibrin, which is the substance
which forms the clot. In the blood of birds and lower vertebrates
the thromboplastin cannot be formed from blood alone, which is due to the
fact that these animals have no true blood platelets. For coagulation
to occur in the blood of nearly all birds there must be some substance
derived from tissue cells.
Thromboplastin is a substance related to the phosphatids
and it an be extracted from injured tissues by means of ordinary fat-solvents.
The Morawitz theory assumes that thrombin exists
in the circulating blood in an inactive state (prothrombin; thrombogen).
Thrombokinase is produced by the action of calcium salts on some tissue
extract or some product of injured living cells. Or, by the simultaneous
presence of calcium salts and cell products without chemical relationship,
the same effect is produced. This thrombokinase acts upon the thrombogen
(prothrombin) causing it to become transformed into thrombin. The
cell product is called a thromboplastic substance. Soluble calcium
salts must be present in order that the thromboplastic substance and the
prothrombin may form thrombin, but it is doubtful whether the salts enter
into chemical relationship with the thromboplastic substance or not.
Several variations of these two theories have been
offered, but they are based upon one or the other of the two just described.
It will be noticed that they differ only in the points affecting the development
Coagulation occurs under several different circumstances
and the essential nature of the process must vary to some extent with these
circumstances. Artificial and experimental methods as well as the
conditions which occur under pathological conditions must be considered.
The coagulation which occurs within the blood vessels, that which occurs
upon the surface of a wound and within the meshes of injured tissue, that
which occurs outside the body in whole blood and that which occurs when
blood is coagulated after various experimental procedures present different
phases of activity.
Intravascular clotting or thrombosis occurs under
different circumstances. Extracts from injured cells are always concerned
in thrombosis, and it is rare that injured blood cells themselves are the
important factors. When the blood vessels are injured, the endothelial
cells produce the extract needed for clotting. Such a clot begins
at the site of injury, gradually fills the vein and may extend toward the
heart until the clot has reached the next branch of the vein; the clot
may continue past one or several branches of the veins and these also become
filled with the clot. Fragments may be broken from the clot and pass
in the blood current as emboli, with further pathogenic influences.
Thrombus formation presents several peculiarities.
The part of the thrombus first formed contains a great abundance of platelets.
These apparently have agglutinated for some reason. In certain cases
it seems that some change in the platelets themselves facilitate abnormal
agglutination. In other cases it seems that some abnormal current
of blood causes mechanical grouping of the platelets with resultant adhesion
and agglutination. The grouping of floating elements of like weights
and sizes in the eddy of a stream illustrates the method of grouping of
platelets at the site of an aneurysm or in vessels which are irregularly
dilated. The presence of a foreign substance, an injury to the vessel
wall, or an inflammation of the intima may initiate accumulation and agglutination
of the blood platelets, and the thrombus follows inevitably. In many
cases of thrombosus it is impossible to determine the cause of the intravascular
Blood found in the serous cavities at operation is
usually free from clots, though it may have been outside the blood vessels,
so far as can be determined from the symptoms for several hours.
Absorption of such blood can occur. From experimental evidence it
seems that many cells become degenerated, but that some of them may be
absorbed by the peritoneal lymphatics. The plasma seems to be absorbed
chiefly by the capillaries and veins. In other cases of peritoneal
hemorrhage blood clots are found at operation. It is not known whether
this is due to some difference in the rate of bleeding, in the quality
of the blood or in some condition of thrombokinase, antithrombin or fibrinogen.
There is no reason for supposing that there is any difference in the calcium
content of the blood which coagulates in the peritoneal cavity and that
which does not clot under apparently identical circumstances.
Foreign substances in the blood stream may cause
coagulation. It may be that the blood cells injured by the foreign
substance provide the necessary cell extract, but in nearly all cases it
is the injured endothelium which produces this substance. The floating
foreign particle rarely, if ever, forms the nucleus of a clot. It
is quite possible that this is due to the fact that the particle ceases
to float as soon as it is surrounded by coagulum. An embolus derived
from a thrombus serves as the starting point of other thrombi; in this
case the thrombus is itself a foreign substance.
Intravascular coagulation may occur as a result
of the injection of solutions containing tissue extract, such as may be
derived from testis, thymus, lymph nodes, spleen, liver, and other tissues
rich in nuclei. Extracts may be prepared from any of these tissues
which cause speedy coagulation of the venous blood when they are injected
in a vein. It seems to be nucleoalbumin or some related phosphoprotein
which causes the clotting, and its manner of action is not clearly understood.
In terms of Howell’s theory, such a substance neutralizes the antithrombin.
In terms of the Morawitz theory the extracts provide a thrombokinase.
If the animal is poorly nourished the clot is confined to the vein injected.
The well-fed animal, under the same circumstances, produces clot through
all the veins.
If, however, instead of a single mass injection of
the tissue substance is made, a series of injections of very small amounts
of the same substance are given an animal the coagulation time may be greatly
prolonged. By careful manipulation of the extracts and of the nutrition
of the animal the coagulability of the blood may be completely destroyed.
It is not possible to act upon blood in vitro in such a way as to secure
such changes and the repeated injections of small amounts of the cellular
extracts must cause a reaction on the part of the living cells of the body
somewhat similar to that caused by mild infections or by the absorption
of the products of infectious processes within the body.
The stroma of mammalian erythrocytes from which the
hemoglobin has been washed facilitates clotting. If any considerable
amount of this stroma is made into a suspension and injected into the veins
of an animal, even of the same animal from which the erythrocytes were
derived, the blood clots within the blood vessels within a few minutes.
This stroma is not related to fibrinogen but is composed chiefly of cholesterin
or some similar lipoid.
ORIGIN OF FIBRINOGEN
Fibrinogen is present in the circulating blood and
in various tissue fluids, such as lymph, chyle and certain transudates
and exudates. Fibrin may be found in the sputum, urine, various inflammatory
exudates and occasionally in the contents of cysts. Fibrinogen may
occur in these fluids also, in which case coagulation can be produced by
the addition of thrombin, calcium or tissue extracts, according to the
lacking factor in the fluid being examined. Fibrin in sputum and
in certain inflammatory products and certain cyst contents presents a gross
resemblance to mucus. The differentiation is made by chemical and
Fibrinogen in the circulating blood is not very abundant.
It is a globulin which is constantly being utilized as a food by nearly
all the cells of the body. It is formed chiefly in the liver but
is also formed, to some extent, by the intestinal walls, the spleen, the
bone marrow and, possibly, by certain leucocytes of myeloid origin.
The lymphocytes seem unable to form any fibrinogen at all, and the endothelial
cells of the blood are very inefficient as manufacturers of fibrinogen.
The amount of fibrinogen in the circulating blood
is greatly diminished in human subjects suffering from any disease of the
liver except abscess and cancer. Phosphorous poisoning, acute yellow
atrophy and any form of cirrhosis of the liver are associated with extremely
small fibrinogen content. In such cases the coagulation time is not
greatly increased but the resultant clot is very soft; in some cases the
blood may not form a recognizable clot at all.
In animals the removal of the liver from the circulation
by any operative procedure (or its destruction by poisons) prevents the
development of fibrinogen after this substance has been removed from the
Both human and animal subjects with bony lesions
affecting the circulation through the liver show similar but less marked
effects. The clot is formed almost or quite within the normal time
but it is soft and the clot does not retract readily. After the correction
of the lesion the fibrinogen returns to its normal amount within a few
weeks or months, according to the size of the animal and according to the
diet and the nutritive condition of the human subject.
Under certain physiological conditions the blood
varies in coagulability without regard to the fibrinogen content.
Increase in the epinephrine content of the blood
hastens coagulation. This occurs normally whenever an animal becomes
angered or frightened and there is much reason to believe that the same
reaction occurs under emotional excitement in man.
The place of adrenal secretion in modifying coagulation
is of importance. The experiments of Cannon and others are enlightening.
As a result of fright or anger the adrenals secrete increasing amounts
of epinephrine, and this increases the coagulability of the blood.
The biological significance of the reaction is apparent; the speedy closing
of the wounds anticipated in battle is thus facilitated. The contraction
of the peripheral blood vessels under similar circumstances has also the
effect of preventing serious hemorrhage from superficial wounds.
Epinephrine added to blood in vitro does not hasten its clotting, and the
addition of epinephrine to the blood of animals does not affect its coagulability
unless the circulation of the blood through the liver remains unimpeded.
The diminished coagulability of the blood of humans with atrophy of the
liver or with certain serious degenerations of liver cells is of interest
in this connection.
Repeated massive doses of epinephrine may delay coagulation
of the blood of dogs, and may even destroy coagulability altogether.
By varying the amounts it is possible to hasten or delay coagulation time
or to cause prolonged or delayed changes in coagulability.
THE SPLANCHNIC CENTERS
Direct stimulation of the splanchnic nerves increases
coagulability. This reaction does not occur in animals whose adrenals
have been removed, which suggests that the nervous stimulation of the adrenals
might be responsible for the effects of splanchnic stimulation.
Human subjects with lesions affecting the splanchnic
spinal centers show diminished coagulability; this more commonly displays
itself in a soft clot with little or no retraction than in increased coagulation
time. Such persons have almost always a low blood pressure, weakened
heart action and some visceroptosis, all of which indicates diminished
activity of the adrenals. However, the presence of bile pigments
in the blood of these persons suggests also diminished hepatic activity,
and since the liver is the chief source of fibrinogen the lack of this
substance may be the most important factor in the effects of splanchnic
vertebral lesions. Further work must be done before these relations
can be explained.
DEFIBRINATION OF DRAWN BLOOD
The fibrin can easily be removed by heating and
stirring freshly shed blood with any slender rough rods, such as metal
wires or wooden sticks. The fibrin is deposited upon the foreign
substance and thus can be removed easily, leaving the serum and the cells
in a fluid state. The fibrin holds some red cells, many hyaline cells
and nearly all the granular cells within its meshes. A differential
blood count made of the fluid blood therefore shows an undue proportion
of hyaline cells. Normal blood which has been defibrinated is useful
for a study of the changes occurring in vitro in the cells of the shed
blood. The injection of defibrinated blood into the veins of the
person from whom the blood was taken, or into the veins of anemic persons,
has been used in therapy.
EXPERIMENTAL PREVENTION OF COAGULATION
Animals differ somewhat in the coagulability of
blood. The vein of a horse can be tied in two places, enclosing any
convenient length of vein between the ligatures. The vein then can
be severed above the highest and below the lowest ligature and it will
then retain the blood in a fluid state for a long time, sometimes for several
days. If this bag be kept quiet, the corpuscles sink to the lowest
part and the supernatant plasma may be poured off into another vein or
into a glass vessel which has been coated thoroughly with paraffin or some
other perfectly smooth surface. If the plasma is poured into glass
or other vessels, not specially treated, coagulation occurs almost immediately.
Horses’ blood received into a prepared vessel at 0 degrees C. and kept
at that point does not coagulate.
The blood of a bird coagulates very quickly after
ordinary wounding. But the blood can be removed from a vein by means
of an oiled or paraffined canula, avoiding contamination of the blood by
any substance derived from the tissues, and coagulation may not occur for
several days, if all dust and foreign matter be kept away. Such blood
can be centrifuged and the plasma and cells secured separately.
Several salts can be added to the blood which prevent
coagulation. Human blood to be used for chemical tests is usually
taken from a vein by a sterile syringe and immediately thrown into a vessel
containing a few crystals of sodium citrate or sodium oxalate. The
oxalate precipitates the calcium. One part of oxalate to 1,000 parts
of blood is sufficient. Rabbits, cats, dogs, guinea pigs and other
laboratory animals have speedier clotting time. In taking their blood
for chemical tests we use a syringe which has been rinsed in oxalate or
citrate solution, and put the blood into a vessel also rinsed with the
same solution, in order to prevent clotting. The corpuscles settle
out of oxalated blood or they may be thrown down more quickly by centrifuging.
Oxalated blood or plasma can be made to clot by adding some suitable calcium
The citrate has a somewhat different action.
This salt does not precipitate the calcium but it enters into the formation
of a double salt, sodium calcium citrate, in which the calcium is in the
anion; that is, the calcium is associated with the acid radicle while the
sodium is the kation. Coagulation does not occur, even in the presence
of a soluble calcium salt, unless the calcium is ionized past the kation.
This condition is present in calcium chloride and calcium sulphate.
Either of these salts added to either oxalated or citrated plasma or whole
blood is followed by almost immediate clotting.
The addition of one part of a 25% solution of magnesium
sulphate to four parts of blood prevents coagulation in the blood of any
mammal for an indefinite length of time. Magnesium sulphate precipitates
the thrombokinase but this reaction proceeds slowly. If the blood
is centrifugated immediately the plasma is clear and fluid, but it coagulates
within a short time after it has been diluted to about the normal specific
gravity. But if the magnesium salted plasma of whole blood is allowed
to remain for one to several days then neither dilution nor the addition
of tissue extracts causes clotting; evidently this is due to the precipitation
of the thrombokinase by the salt.
The addition of one part of a half-saturated solution
of sodium sulphate to one part of blood also prevents coagulation of the
blood of any mammal for an indefinite time. Either the whole blood
or the plasma freed from the cells coagulates at once after dilution with
water to about the original specific gravity of the blood.
ORGANIC SUBSTANCES WHICH PREVENT COAGULATION
Certain animal extracts prevent coagulation in vitro
or when injected into the veins of the animal.
Hirudin is an extract made from the anterior part
of the body of a leech. The prolonged bleeding time of wounds produced
by the bites of leeches has long been known. The efficiency of leeches
in old-time methods of treatment by bleeding depends upon the fact that
a peculiar albumose derived from the buccal glands of the leech was injected
into the tissues of the wound, and this prolonged the bleeding time.
Blood received into a vessel containing a solution of hirudin does not
coagulate. Hirudin injected into the veins of an animal prevents
coagulation within the blood vessels after death. Blood drawn either
before or after the death of the animal injected with hirudin does not
Since hirudin is an antithrombin, blood which has
been prevented from clotting by its use needs only to have thrombin added
to it in quantities beyond the efficiency of the hirudin still present.
Clotting then occurs.
A solution of peptone injected into the veins of
an animal prevents the coagulation of the blood both within the vessels
after death and in vitro whether the blood is removed before or after the
death of the animal. Peptone does not prevent coagulation if it is
added to the blood in vitro, however. The nature of the physiological
relations concerned is puzzling An animal which has received an injection
of peptone and has thus the coagulability of its blood diminished or destroyed
cannot be used for a second similar test for several weeks. At any
time within a few days a second or later injection of peptone solutions
has little or no recognizable effect on coagulation. There is no
other recognizable change in the physiological condition of the animal
under such circumstances.
A solution of peptone perfused through an extirpated
liver causes the appearance of an anti-coagulating agent in the hepatic
veins. This agent seems to act by neutralizing the fibrin ferment
but its nature is not yet known.
Peptone is much more efficient as an anti-coagulant
if the animal to be employed has fasted for a few hours before the experiment
is begun, and if the peptone be injected rather slowly. An anticoagulin
is formed within the liver and this may be antithrombin.
Peptone plasma can be induced to clot by adding an
extract from tissue cells to it, or by passing a stream of carbon dioxide
through the vessel containing it. The addition of ordinary amounts
of fibrin ferment may induce coagulation in peptone plasma or peptone whole
Venoms from snakes and other lower animals produce
different effects on coagulation. The venom of the cobra inhibits
coagulation whether it is injected into the blood in minute amounts during
life or is placed in a vessel into which the blood is to be received.
Other snakes (for example the pseudechis porphytacrous) produce a venom
which causes abundant coagulation within the vessels of a living body,
such as might follow the injection of tissue extracts into the blood stream.
It is not known to what constituents of the venom this effect is due.
Certain intestinal parasites produce a substance
which prevents coagulation. Wounds made by them in the intestinal
wall continue to bleed for a long time and the entire blood may show greatly
diminished coagulability because of the absorption of this substance.
The severe anemia due to the hook worm, the dibothriocephalus latus and
other intestinal worms is thus explained.
COAGULATION AT VARIOUS PERIODS OF LIFE
There is little change from birth to senility in
the coagulability of normal blood. The coagulation time has been
determined for newly born infants by many authors. The figures vary
slightly from four to ten minutes, with an average of seven minutes; this
is longer than the average coagulation time of adults. Newly born
infants with hemorrhages show greatly prolonged clotting time and increased
coagulation time. Intramuscular or intravenous injection of paternal
or other whole blood frequently provides the necessary substances and after
coagulation of the blood has been established the hemorrhages may cease.
For a day or two before menstruation begins the
coagulability of the blood is slightly diminished for about two-thirds
of the women examined. The old idea that menstrual blood does not
coagulate is untrue; any blood mixed with mucus coagulates with difficulty
or not at all. The presence of mucus and of degenerated endometrial
cells prevents coagulation to some extent. Pure menstrual blood coagulates
as quickly as does blood derived form the veins of any part of the body.
During pregnancy the coagulability of the blood
is somewhat diminished; possibly the developing embryo or fetus needs the
serum albumins and globulins. Before labor an increased coagulability
of the blood is occasionally noted. The biological relations of these
facts are self-evident.
The blood from embryos shows low coagulability.
In pig embryos from 100 to 250 millimeters in length the average coagulation
time was found by Emmel and others to be twenty-three minutes. The
adult pig’s blood coagulates within about three minutes. Addition
of adult pig platelets or of extracts of adult cells to the embryonic pig’s
blood caused coagulation to occur within three to four minutes. Calcium
is higher in the blood of embryonic pigs than in the blood of adult pigs.
In normal old persons the coagulability of the blood
is normal or only slightly hastened. Various diseases affect senile
blood rather more seriously than younger blood but there is no quantitative
variation in the effects after adult life has been reached, so far as coagulation
COAGULATION IN DISEASE
Variations in the coagulability of the blood in
certain diseases present even more puzzling problems. The abnormal
conditions of coagulation include (a) delayed clotting (b) imperfect nature
of the clot (c) hastened clotting The causes of these different abnormal
conditions of coagulability may differ considerably.
There may be a lack of fibrinogen in the circulating
blood. This causes the formation of a soft and imperfect clot which
permits prolonged bleeding from wounds which may be almost negligible.
Lack of fibrinogen is known to occur when the liver is seriously injured,
as in cases of poisoning by phosphorous or chloroform, or in cases of hepatic
cirrhosis or acute atrophy, or in fulminating cases of certain infectious
diseases. There is not any delay in coagulation in uncomplicated
cases of deficiency of fibrinogen.
Morawitz considers lack of thromboplastin (prothrombin)
an important factor in cases of delayed coagulation. It is difficult
to see how there could be a lack of a substance derived from injured cells,
especially as injured blood cells may produce it. It is possible
that a disturbance in the metabolism of the cells, necessarily of developmental
and constitutional nature, may so affect the end-products of katabolism
that the thromboplastic substances are inefficient in the transformation
of prothrombin to thrombin.
Deficiency of calcium salts was at one time considered
important in the etiology of delayed coagulation. That the blood
always contains enough of the soluble calcium to provide for coagulation
seems definitely proved. Increased calcium intake does not hasten
coagulation in any useful degree, though certain cases of delayed coagulation
in obstructive jaundice seems to be somewhat improved by increased calcium
intake. Deficiency of prothrombin is present in cases of melena neonatorum.
In these cases intramuscular infusions of whole blood or intravenous injection
of blood serum or of whole blood are usually efficient in relieving the
condition, by adding the necessary prothrombin to the blood of the infant.
Excess of antithrombin may prolong coagulation.
Certain chemical agents, such as hirudin, act as antithrombins and coagulability
may be completely destroyed by such substances injected into the blood
Lack of blood platelets diminishes coagulability,
since these structures are the chief source of prothrombin, probably also
Increased rapidity of coagulation may occur as a
result of increased amounts of epinephrine, as already noted, under experimental
conditions. It does not seem to occur as a result of disease.
Increased amounts of antithrombin occur in pneumonia and this fact is useful
in diagnosis. In septicemia and in miliary tuberculosis there may
be excess of antithrombin. The biological significance of increased
coagulability in these diseases is evident.
Hemophilia is a puzzling disease which is characterized
by a marked tendency to continued bleeding from wounds apparently insignificant.
The blood coagulates in vitro within a normal time, but the clot is soft
and fails to show retraction present in a normal clot. In this disease
the platelets are normal in number but they do not agglutinate properly,
and it seems that they lack the ability to form prothrombin. The
nature of this functional defect is not known, but the hereditary character
of the disease indicates that the defect is inherent in the germ plasm.
The blood of a hemophiliac contains normal amounts of fibrinogen, calcium,
salts, and platelets; the blood cells are normal in both actual and differential
counts. A normal clot is formed in vitro from the blood of hemophiliacs
if kephalin is added to it. If the tissue of the bleeder is bruised
or if the blood flows over injured tissues after leaving the vessels, the
blood clots and the clot retracts as in normal blood. These various
observations indicate that the platelets defect is essential in the disease
Another peculiarity of the blood platelets of hemophiliacs is their failure
to agglutinate at the site of bleeding points, as do the platelets of normal
Deficiency of platelets may prevent normal coagulation.
Excess of platelets does not cause abnormally rapid coagulation nor the
formation of an abnormal clot. In certain hemorrhagic diseases such
as the leukemias, and in certain infectious diseases, such as “black” smallpox
and “black” diphtheria, the platelets are tremendously diminished.
As a result of leukemia the leucocytopoietic centers crowd out the megakaryocytes,
thus preventing normal replacement of the platelets. As a result
of the exhaustion of the bone marrow, in extremely malignant infections,
the megakaryocytes share in the atrophic changes. In these cases
it is occasionally impossible to find even one platelet by the most careful
methods of taking the blood. In these diseases the coagulation time
remains almost or quite normal but the clot is very soft. The bleeding
time may be prolonged almost indefinitely.
COAGULATION IN HEPATIC DISEASES
The diminished coagulability of the blood in persons
with hepatic disease has long been recognized. Several factors are
concerned in this relationship. The place of diminished fibrinogen
formation as a result of hepatic disease has already been mentioned.
The mixture of bile pigments, and especially of bile
salts, with blood in vitro diminishes coagulability. With hepatic
diseases cholemia is very common; the diminished coagulability may be,
in part, due to the cholemia. The bile interferes with the conversion
of fibrinogen into fibrin, but the amount of thrombin is not affected.
Carbon monoxide poisoning delays coagulation.
In lethal cases the blood may not coagulate at all within the vessels.
In the chronic mild carbon monoxide poisoning which is so common in large
cities the coagulation time is usually prolonged to ten minutes or more
(normal by our methods, four to six minutes).
Deficiency of fibrinogen may prevent the formation
of a normal clot. The coagulation time is not modified, if coagulation
occurs at all, but the resultant clot is soft, does not retract and serves
little useful purpose in closing wounds.
Deficiency in prothrombin is apparently the cause
of melena neonatorum. Intravenous transfusions or intramuscular infusions
of normal blood usually result in supplying the lacking factor to the infant’s
blood and recovery usually follows promptly.
Deficiency in thromboplastin has been emphasized
by Morawitz. Since this substance is derived from injured cells of
blood or tissues its presence would seem almost inevitable. Possibly
there is some developmental defect in the cells of bleeders of this group.
Excess of antithrombin occurs under experimental
conditions such as the injection of hirudin or peptone into laboratory
animals. An excess of antithrombin is said to occur during the course
of septic diseases, especially those affecting the lungs.
FIBRIN FORMATION ON THE WARM SLIDE
The manner in which the fibrin threads appear on
the warm slide which is practically a vital phenomenon, gives much useful
information. The slide is kept at 99 degrees F., to 100 degrees F.
usually by means of an electric appliance made for the purpose. The
blood is placed on this slide directly from the exuding drop, is immediately
covered with a warm cover-glass and examined immediately. Hence the
blood is under physiological conditions, except for the lack of circulation
and the recurring variations of oxygenation, nutrition and so on.
Vital phenomena occur under such circumstances almost normally. The
presence of the foreign bodies, the slide and cover-glass, initiate reactions
similar to those occurring within the body around a foreign body, if not
identical with them. The manner in which fibrin is formed under such
circumstances presents variations which are often very useful in diagnosis.
Normal blood placed on the warm slide begins to show
fibrin threads after about ten minutes. If the slide is warmed to
103 degrees F. fibrin threads may appear within five minutes. The
threads are very fine, so that accurate measurements have not yet been
found practicable under the circumstances of the warm slide preparations.
When threads of fibrin fail to appear upon the warm
slide within about ten minutes, the condition is distinctly abnormal.
In persons whose diet fails to include a proper amount of protein foods,
but who are not utilizing their own muscles as a source of energy, the
amount of fibrin may be extremely scanty and may appear only after fifteen
minutes or more. The greatest delay and the greatest lack of fibrin
upon the warm stage occurs in persons with serious hepatic disease, but
not in cancer of the liver, either primary or metastatic, nor in abscess
of the liver. The even caliber of the normal threads is noticeable.
The threads vary in length. When first visible, they are from three
to six microns long. During the fifteen minutes following their first
appearance they increase in length, at first visibly, then more and more
slowly. By careful watching it is usually possible to say that the
fibrin formation ceases at a definite minute.
Abnormally fibrin may be present as soon as the slide
is seen under the microscope, or it may not appear at all, or only after
half an hour or more on the warm slide.
In normal blood the fibrin threads appear to have
no relationship with one another, and rarely to any other blood structures.
Occasionally they seem to originate from a group of platelets; this is
in normal blood at correct temperature. The threads are straight
and they may or may not lie across one another.
Abnormally many fibrin threads radiate from groups
of platelets or from white cells; they form net-like arrangements which
may be quite complicated in structure; they may be so related with phagocytes
as to appear to be merely continuations of abnormally long and slender
pseudopodia; they may be abnormally long and abnormally heavy, or they
may present marked irregularities in contour or they may even have sharp
variations in thickness so that they present a definitely beaded appearance.
The significance of these variations is not yet clearly
understood. Much further work must be done before the problems presented
by these most interesting reactions are solved in any satisfactory manner.
But there are useful indications of diagnosis and prognosis to be gained
from a study of fibrin formation as it occurs on the warm slide.
Fibrin develops very speedily under several conditions,
and in many cases this is of great value in early diagnosis.
FIBRIN IN PNEUMONIA
In lobar pneumonia fibrin develops immediately and
abundantly. The threads are long, heavy, fairly even in content,
not arranged in nets but often so abundant as to present a felted appearance.
The fibrin is completely formed within a very few minutes or, occasionally,
is completely formed at once, so that no increase in the length of the
threads is visible. By the time the slide is placed under the microscope,
very often, the abundant heavy threads are easily visible. This reaction
is present in such degree in no other acute disease, and it occurs so early
that a diagnosis of lobar pneumonia can often be made twenty hours before
any other pathognomonic finding can be secured. During the course
of the disease and for several weeks after recovery this rapid fibrin formation
is present. It disappears gradually and the blood returns to the
normal condition after some weeks,--the exact time for recovery of normal
fibrin relations has not yet been studied.
In aborted cases of pneumonia this fibrin reaction
also occurs and it is possible to determine whether or not an actual pneumonia
has been aborted by a study of the fibrin at any time within a week after
the initial symptoms have disappeared.
In ordinary colds, in cases of influences without
pulmonary involvement, in bronchitis without alveolar involvement and in
other infections without lung disease but presenting symptoms that might
be confused with early pneumonia, the fibrin formation is either normal
or only feebly modified.
FIBRIN IN MALIGNANCY
In active carcinoma the fibrin formation is very
rapid, and in some cases is as rapid as in pneumonia. In malignancy
the threads are uneven in contour and there may be so many and such marked
inequalities that the threads present a definitely beaded appearance.
The threads often radiate from a small group of platelets or from a white
blood cell, usually a lymphocyte. In cases in which there is some
difficulty of diagnosis, the presence of these irregular fibrin threads,
appearing quickly and in great abundance, suggests carcinoma. In
sarcoma the fibrin threads present less marked modifications, and the reactions
are of much less significance.
FIBRIN IN MALNUTRITION
In malnutrition the fibrin threads are extremely
fine, delicate and scanty. If the malnutrition is associated with
any marked toxemia, the threads are apt to be uneven in contour.
If there is little or no toxemia, the threads are even and regular, but
are so very fine that it may be difficult to see them at all, except when
the field is darkened or a dark-stage illuminator is used. The fibrin
formation is considerably delayed in malnutrition, often to twenty or thirty
minutes after the blood is placed on the warm slide.
When malnutrition is associated with malignancy or
with early pneumonia, the fibrin threads become heavy, abundant, irregular
and are formed very speedily, as in ordinary malignancy and pneumonia.
In other diseases associated with moderate increase in the fibrin threads,
the presence of severe malnutrition modifies the fibrin reactions, so that
it may often be difficult to determine the relationships of the fibrin
studies. Fortunately most of the conditions in which there are complicating
factors are those in which some other laboratory findings or some symptom
complex helps in differentiation.
The fibrinolytic ferment was first studied in the
laboratory of The A. T. Still Research Institute in Chicago. Since
that time it has been studied in other laboratories of the Institute and
in several other laboratories, though the subject has not yet received
the attention to which its importance entitles it.
Normal blood usually contains an enzyme which digests
the fibrin of the blood clot but which does not digest the cells of the
blood or the tissues of the body. The blood of approximately one-fourth
of all persons, healthy or ill, fails to contain this ferment. The
fibrinolytic ferment is destroyed by heat above 108 degrees F., and its
activity is diminished at 104 degrees F. and by temperatures below 96 degrees
F. Tests have not yet been made determining the low point at which
the enzyme is destroyed. Fibrinolysis is decreased by the use of
distilled water in the tests and by the presence of any appreciable excess
of the salts present in tap water or spring water.
Roseman was able to precipitate a fibrinolytic substance
from fibrin autolysate. A similar substance was extracted from the
pressed juice of pneumonic lung. This substance differs from leucocytic
trypsin in its greater thermolability and by the fact that it is not related
to the leucocytic content of clot. The exudates from tubercular scrositis
markedly retards fibrinolysis. Roseman also later reported that the
fibrinolytic substance of horses’ blood serum is precipitable by alcohol,
ammonium sulphate and zinc chloride. It is not dialyzable.
Temperatures of 46 degrees to 48 degrees C. are destructive. Tubercular
exudates inhibit fibrinolysis by this enzyme also. Human material
gives the same findings, according to Roseman.
The function of this ferment in normal life is not
known. Inasmuch as persons who lack the ferment show no evil effects
referable to its lack, except as shown later in this chapter, its function
may be altogether protective. Possibly other ferments may perform
similar or identical functions under ordinary circumstances.
The function of fibrinolysis is most easily recognizable
after the repair of wounds. When any tissue is injured, the blood
vessels of the immediate vicinity are dilated. An increased amount
of fluid passes into the tissue spaces. Usually the capillaries of
the part are also injured so that there is some extravasation of blood
(hemorrhage per rhexin of the older pathologists). If there is no
frank bleeding the dilatation of the blood vessels permits some escape
of blood from the capillaries (hemorrhage per diapedesin). The fluid
derived from the blood plasma as well as the blood itself undergoes coagulation
throughout the areas involved. The clot contracts very slightly and
this reaction forms a fairly firm substance which exerts pressure upon
the periphery of every living cell within the area.
This pressure exerts the same influence upon the
cellular contents as that which is exerted by a cell wall. The mature
cells of animal bodies do not have a cell wall, and their surfaces offer
no resistance to the growth or the swelling of the cell. Mature animal
cells continue to grow until the metabolic control of the nucleus is reached
but they do not undergo division unless the cell contents are subjected
to pressure. The coagulum exerts such pressure. The cells imbibe
some fluid from the surrounding edematous fluids which, in turn, are due
to the vaso-dilatation. With increasing intercellular pressure the
phenomena of karyokinesis are initiated in some of the cells and they divide.
This division of the cells is necessary to the repair of the wounds.
Not only the tissue cells themselves but also the various hyaline cells
of the blood and of the tissue spaces begin to divide in the same way (plasma
cells, macrophages, lymphocytes, monocytes and others).
These processes follow a definite series of events
which differ slightly according to the histological characters of the tissue
which has been wounded but which always include the multiplication of several
types of cells after a preliminary pressure due to the clotting and the
swelling due to the edema. The ingestion, digestion and removal of
the debris left by the injured tissues is also an essential part of the
phenomena of repair.
When cell division is no longer required the clot
must be removed. In persons whose blood contains the fibrinolytic
ferment the digestion of the fibrin of the clot begins within about twenty-four
hours and is complete within about fifty hours. If the wound is simple,
without any serious bruising of the tissues and no infection; that is,
if the wound is repaired by first intention, there is little or no need
for further cell division after the first day or so. The digestion
of the fibrin thus removes the impulse to karyokinesis and no further multiplication
of the cells occurs. If the fibrinolytic ferment is absent the various
microphages and macrophages must destroy the coagulum; this is a slower
process and there is some reason to believe it less efficient than normal
After inflammations of any ordinary type, the presence
of normal fibrinolysis facilitates the removal of the remaining coagulum.
Persons recovering from pneumonia may show rapid and complete resolution
if their blood contains normal fibrinolysis, or resolution delayed with
a greater amount of cirrhosis if the blood lacks fibrinolytic ferment.
During high fever and under certain other conditions
there is produced a non-specific proteolytic ferment in marked degree.
This ferment is present in the blood of all persons in a very slight amount,
and it may be very greatly increased during high temperatures. This
non-specific proteolytic ferment facilitates the digestion and removal
of coagulum even in persons without fibrin ferment, so that the lack of
fibrinolysis is not a serious matter in those cases characterized by hyperpyrexia.
Low grade inflammations do not initiate any great increase in the non-specific
proteolytic ferment (or ferments), and persons whose blood lacks the fibrinolytic
ferment show delayed resolution, a greater amount of connective tissue
hyperplasia and more serious adhesions after recovery from inflammations
with mild pyrexia than do persons with normal fibrinolysis.
For example, of many patients with severe acute inflammatory
rheumatism with high temperatures about one-fourth have no fibrinolysis
while about three-fourths have normal fibrinolysis. All of these
patients develop an abundant supply of the non-specific proteolytic ferment
during the high fever. The coagula of the inflamed areas are digested
and absorbed, and there is no recognizable difference between the two groups
of persons so far as recovery is concerned. On the other hand, of
a considerable number of persons with some low-grade arthritis characterized
by little or no fever, about one-fourth have no fibrinolytic ferment while
about three-fourths have normal fibrinolytic ferment. As a rule (not
without exceptions) those persons without fibrinolytic ferments have greater
hypertrophy of the affected joints with denser adhesions than do the persons
with normal fibrinolysis. Of all persons with any type of chronic
articular rheumatism about eight-tenths have no efficient fibrinolytic
ferment. That is, persons with normal fibrinolysis have a partial
immunity or else they recover more speedily.
The place of fibrinolysis in protection against malignant
neoplasms has been studied with some care. Animals which have about
the same cancer-incidence as human beings have about the same fibrinolysis
incidence, that is, about one-fourth of all individuals lack the ferment
while about three-fourths show its presence in the blood serum. Animal
families which seem to be immune to cancer all show normal fibrinolysis.
Animal families which have no immunity to cancer have no fibrinolysis.
In human families in which cancer never occurs, all
members have blood with normal fibrinolysis. In human families in
which there are many cancers both in the paternal and maternal line of
inheritance, the fibrinolytic ferment is absent in nearly all individuals.
That is, many persons of the human race inherit an important factor of
protection against cancer. Persons who do not have this factor of
protection against cancer may still fail to develop cancer.
For the development of certain kinds of cancer repeated
irritation seems to be necessary; for other kinds some chronic inflammatory
processes seem to be necessary. Other types of cancers arise from
some developmental defect. For all kinds of cancer the cooperative
activity of two or several pathogenic processes seems to be necessary.
The lack of the fibrinolytic ferment is one factor which is common to many
cancer-producing conditions, among animals and human subjects alike.
Attempts have been made to produce the fibrinolytic
ferment in persons not naturally provided with this substance.
Neutrophiles in severe cholemia. From patient
with cancer of the liver, a few days before death. The protoplasm
is eroded, leaving the nuclear masses.
Persistent vegetable diet does not lead to its development.
This test was repeated in human beings because of the rather common idea
that vegetarianism tends to diminish cancer development. In this
connection it may be said that certain gramnivorous animals are very prone
to cancer, and that other gramnivorous animals are almost or quite immune;
that certain carnivorous animals are prone to cancer and other carnivorous
animals are immune; that of any animal group certain strains or families
may be immune while other strains or families may be unusually susceptible.
The animals most thoroughly studied in this connection are all laboratory
animals, kept under conditions as nearly normal as is practicable for animals
DIRECT ADDITION OF FIBRINOLYTIC BLOOD
Persons known to have cancer, and in whose blood
no fibrinolysis can be shown, have been treated by giving them infusions
of the blood of persons whose blood is known to be well-provided with the
fibrinolytic ferment. The number of cases so treated is too few to
warrant definite statements. The patients so treated were those for
whom recovery could not be expected under ordinary methods of treatment,
and a few of these have recovered from the cancer and have lived without
recurrence for ten years or more. Such persons have shown normal
fibrinolysis for six years or more after the last administration of blood.
Normal blood has been given to patients whose blood contained no fibrinolysis
and who suffered from arthritis deformans with unusually dense adhesions;
normal fibrinolysis was established in these cases and further adhesions
did not occur in the joints.
About two cubic centimeters of blood were taken from the
vein of a donor known to be in excellent health and free from any infection,
and injected into a muscle of the recipient. Usually two or three such
infusions at three to five day intervals resulted in the development of normal
fibrinolysis on the part of the recipient. This method presents certain
possibilities for cases otherwise hopeless but is not to be commended as a routine
Tests have been made in an attempt to find that some especial
organ or tissue produced the fibrinolytic ferment, in the hope of finding some
cause for its absence other than heredity. No tissue has been found to
be solely or especially capable of producing it. Persons lacking this
ferment do not show any particular lesions. Persons lacking it do not
develop it after the most persistent osteopathic treatments, no matter what
lesions were present before the treatments were begun. Persons normally
provided with this ferment do not lose it, though the activity of the ferment
is delayed or subnormal during the course of several abnormal conditions.
Much more study is necessary before definite reports can be made as to the relations
between abnormal conditions and the delay or inhibition of fibrinolysis in persons
normally provided with the ferment. It is not now possible to say that
there is any lesion or any disease which exerts a specific action upon fibrinolysis.