Blood serum

“ As is well known, blood serum possesses, as a rule, a bactericidal power upon most micro-organisms, and we have every reason to believe in the existence of specific substances in the serum which exert some influence upon the growth and development of micro-organisms, and also upon the toxic products they tend to elaborate. These protective substances—the alexins of Buchner—appear to be proteid in nature, resembling globulins, since they are precipitated from serum by the action of certain strong solutions of alkali salts, as sodium sulphate. ”

“ Now add 300 c.c. clear blood-serum (vide page 168, sections 1 to 4) to every 100 c.c. of this bouillon.
4. Fill into sterile tubes and complete as for ordinary blood-serum.
Blood-serum (Lorrain Smith) .—
1. Collect blood-serum (vide page 168, sections 1 to 4) , as free from hæmoglobin as possible.
2. Weigh out 0.15 per cent. sodium hydrate and dissolve it in the fluid (or add 0.375 c.c. of dekanormal soda solution for every 100 c.c. of serum) .
3. Tube, and stiffen at 100° C. in the serum inspissator.
4. Incubate at 37° C. for forty-eight hours to eliminate any contaminated tubes. ”

“ In order that it may exert this power it requires the presence of a substance normally present in the serum known as “complement.” The development of these “anti-bodies,” though it has been studied mainly in connexion with bacteria and their toxins, is not confined to their action, but can be demonstrated in regard to many other substances, such as ferments, tissue cells, red corpuscles, &c. In some animals, for example, the blood serum has the power of dissolving the red corpuscles of an animal of different species ”

“ If human defibrinated blood be injected into the peritoneal cavity of a rabbit, the serum obtained from the rabbit‘s blood, when mixed with a clear solution of the blood of man or ape, will produce a precipitate, and agglutinate the red blood corpuscles if present: the same reaction will not follow if such serum be added to a solution of the blood of any other animal. ”

“ The serum, mostly composed of albumen, is a transparent, straw-colored fluid, having the odor and taste of blood. The whole quantity of blood in the body is estimated on an average to be about one-ninth of its entire weight. The distinctions between the arterial and the venous blood are marked, since in the arterial system the blood is uniformly bright red, and in the venous of a very dark red color The blood-corpuscles contain both oxygen and carbonic acid in solution. When carbonic acid predominates, the blood is dark red ”

“ Blood plasma, when obtained free from corpuscles, is perfectly colorless, in thin layers, for example, in microscopical preparation; when seen in large quantities it shows a slightly yellowish tint. The red color of the blood is not due, therefore, to coloration of the blood plasma, but is caused by the mass of red corpuscles held in suspension in the liquid. The proportion by bulk of plasma to corpuscles is usually given roughly as two to one. The blood plasma is composed of two substances, blood serum and blood fibrin. ”

“ But if the spot of human blood were less than the size of a pin-head, it would show—it would show if the spot contained even so little as one twenty-thousandth of a gram of albumin. Blood from a horse, a deer, a sheep, a pig, a dog, could be obtained, but when the test was applied the liquid in which they were diluted would remain clear. No white precipitin, as it is called, would form. But let human blood, ever so diluted, be added to the serum of the inoculated rabbit, and the test is absolute. ”

“ But in certain directions, notably in regard to the relations with micro-organisms, changes in the blood-plasma can be made out, though they are not associated in all cases with changes in the formed elements which float in it, nor with any obvious microscopical or chemical alterations.
The phenomena of immunity to the attacks of bacteria or their toxins, of agglutinative action, of opsonic action, of the precipitin tests, and of haemolysis, are all largely dependent on the inherent or acquired characters of the blood serum. It is a commonplace thatImmunity. ”

“ And this goes on until you have left in the clot very little besides corpuscles entangled in a network of fibrin, and all the rest of the blood has been squeezed outside the clot, and is then called serum. Serum, then, is blood out of which the corpuscles have been strained by the process of clotting.
Now I dare say you are ready to ask the question, If blood clots so readily when it is shed, why does it not clot inside the body? Why is our blood ever{48} fluid? This is rather a difficult question to answer. When blood is shed from the warm body it soon gets cool. ”

“ He tells us that—
“Soon after salivation has been established, the blood exhibits an inflammatory crust; at a later period its colour deepens, and its coagulability is diminished; the proportion of clot, and, therefore, of fibrin, to serum (or watery part) becomes smaller; the formation of albumen and mucus sinks to that of serum; the whole organic formation of the patient is less consistent and cohesive.” ”

“ Extensive effusions of serum, lymph, and pus, mixed in different proportions, will take place in the serous cavities of the body, and become infiltrated in the cellular membrane, accompanied with very slight indications of inflammatory action. The colouring matter of the blood will also sometimes become effused with its other parts; but when this is the case, the blood will be found to have lost its coagulating power: in this respect presenting a direct contrast to the effusion from a healthy wounded vessel. ”

“ If there be a loss of tissue brought about by severe injury to the skin and the deeper tissues, there is usually an extravasation of blood from the severed vessels. Along with the exuded serum this fills up the breach in the tissues and the whole is rapidly formed into a fibrinous mass due to the disintegration of the polymorpho-nuclear leukocytes setting free their ferment. The ferment thus set free brings about the coagulation of the serum, which acts as a protective and temporary scaffolding to the injured tissues. ”

“ A good field is selected, one containing many leucocytes, the number of germs counted in the first fifty or hundred observed, and an average per leucocyte determined. If the average in the mixture containing the normal serum is two, we would say that the normal opsonic index is two, and if the mixture containing the patient’s blood serum is one per corpuscle, we would say that his index was one-half, etc. ”

“ During this momentary crush, part of the serum being forced on too fast, oozes through the wall of the over-filled capillaries, as water oozes through the leathern pipes of a fire-engine, and hence probably the appearance of serum or lymph in the organs, where it is immediately sucked up (i. e., absorbed) by the lymphatic vessels. Now, you will easily understand that the larger the proportion of serum in the blood, the greater will be the quantity to be expelled in passing through the capillaries, and the more will the lymphatic vessels swell. ”

“ Does not the restoration of the blood from its disorganized state, by means of bleeding, suggest an idea of a similar change being practicable in the solids, when they are disorganized by disease? And are we not led hereby to an animating view of the extent and power of medicine?
2. Blood of a scarlet colour, without any separation into crassamentum or serum, indicates a second degree of morbid action. It occurs likewise in the malignant state of fever. It is called improperly dense blood. It occurs in old people. ”

“ It is an observed fact that blood outside the body soon develops the property of auto-hæmolysis. If blood is drawn from a vein, put into a test-tube, and allowed to clot, then after twenty-four hours or more the serum which has separated from the clot begins to be tinged with hæmoglobin, even though it has remained absolutely sterile. It appears, therefore, that the serum develops a hæmolysin and the corpuscles the corresponding iso-hæmolysin, the interaction of which results in the breaking up of corpuscles. ”

“ The liquor sanguinis constitutes fully 66 per cent. of the volume of the blood. It is albuminous in nature and contains a small amount of coloring matter of a fatty nature. It holds in solution three proteids—fibrinogen, serum globulin, and serum albumin.
Second, the organized parts, or the cellular structure (Fig. 74, Nos. 1 to 21) . The cells float in the plasma and consist of three groups: the erythrocytes, or red blood cells, the leucocytes, or white blood cells, and the thrombocytes. ”

“ As already mentioned, the blood is the nutritive fluid of animals. When this fluid is coagulated, a thick, jelly-like mass floats in the serum, called coagulum. This coagulated mass is composed of fibrin, and red globulated matter. The color of the red globules is owing to the presence of iron, though some physiologists think it depends on an animal substance of a gelatinous character.
Observation. That portion of the serum which remains fluid after coagulation by heat has taken place, is called se-ros ́i-ty. It is more abundant in the blood of old, than in that of young animals ”

“ One drop of the serum is then added to nine drops of normal salt solution, making a dilution of 1:10. Distilled water may be used for dilution, but is more liable to cause error. The dilution can be more accurately made in the leukocyte pipet of the Thoma-Zeiss instrument. When the whole blood is used, it can be secured in the pipet and at once diluted with the salt solution. When it must be transported a considerable distance, dried blood is most convenient. A large drop is allowed to dry upon a clean slide or unglazed paper. It will keep for months without losing its agglutinating power. ”

“ These red particles are flattened disks; in man they are round. Their size is variable, being in man from one four-thousandth to one eight-thousandth of an inch in diameter, but larger in other animals.
The blood contains a large quantity of albumen, partly dissolved and remaining in the serum after coagulation, partly in a solid state, forming the great mass of the globules.
In the living body the blood also contains fibrine in solution, but this separates soon after extraction from the body; it assumes a solid form, and investing, as a sponge, the red globules, forms with them the coagulum. ”

“ The blood is thin and the serum tinged. The degenerative changes of the red cells are not as commonly seen as one would expect but this is probably due to the fact that degenerated cells are first destroyed in the excessive haemolysis. Hb percentage reduction generally parallels the reduction in red cells. Melaniferous leucocytes may be found and during the leucopenia, which follows the paroxysm, the large mononuclears and transitionals may be increased to 20%. There is a reduction in the alkalinity and coagulability of the blood. ”

“ In the first periods of inflammations, in which the exhalants of the serous membranes are full of blood which is preternaturally introduced into them, the serum does not ooze in greater quantity from their free surface. Then as they are on the one hand very sensible, and very dry on the other, the motions of the organs that they cover are wonderfully painful. ”

“ If the serum does not contain any defensive ferments against the form-elements of the blood, then, of course, even an organ containing blood may give correct results. As, however, mistaken results are liable to occur, such an organ should, as a rule, never be used.
It is advisable never to use one particular organ exclusively for testing a definite problem; and one should always work with controls. For instance, placenta is always tested with serum from obviously non-pregnant persons. Male serum should also be employed. ”

“ When blood is drawn and allowed to stand it emits a “halitus” or exhalation, which has a faint smell. In three or four minutes a film overspreads the liquid, commencing at the circumference and gradually spreading to the center. Two or three minutes later the lower part of the blood, in contact with the vessel, becomes solidified, and then the whole mass, only about eight or nine minutes being needful for the whole process from first to last. In about 15 or 20 minutes a thin serum begins to exude from it, and goes on to do so for two or three days. ”

“ The red blood corpuscles have consistently shewn themselves as almost exclusively concerned with variations in the specific gravity of the total blood; partly by variations in number, or changes in their distribution; partly by their chemical instability; loss of water and absorption of water, and variations in the amount of iron.
The plasma of the blood on the contrary—and there is no essential difference between plasma and serum (Hammerschlag) —is much more constant. ”

“ The antiserum produced in the case of the red corpuscles may sometimes, if injected into the first animal, whose red corpuscles were used, cause extensive destruction of its red corpuscles, with haemoglobinuria, and sometimes a fatal result.
Opsonic action depends on the presence of a substance, the “opsonin,” in the serum of an immunized animal, which makes the organism in question more easily taken up by the phagocytes (leucocytes) of the blood. The opsonin becomes fixed to the organisms. ”

“ Tested with nitric acid and ammonia, it is found to contain a protein substance which is called fibrin.
Blood plasma, then, is made up of a fluid portion of serum, and fibrin, which, although in a fluid state in the blood vessels within the body, coagulates when blood is removed from the blood vessels. This coagulation aids in making a blood clot. A clot is simply a mass of fibrin threads with a large number of corpuscles tangled within. The clotting of blood is of great physiological importance, for otherwise we might bleed to death even from a small wound. ”