The problems concerned in the nature and cause of tumors are the most important in medicine at the present time. No other form of disease causes a similar amount of suffering and anxiety, which often extends over years and makes a terrible drain on the sympathy and resources of the family. The only efficient treatment for tumors at the present time is removal by surgical operation, and the success of the operation is in direct ratio to the age of the tumor, the time which elapses from its beginning development. It is of the utmost importance that this should be generally recognized, and the facts relating to tumors become general knowledge. Tumors form one of the most common causes of death (after the age of thirty-five one in every ten individuals dies of tumor); medical and surgical resources are, in many cases, powerless to afford relief and the tumor stands as a bar to the attainment of the utopia represented by a happy and comfortable old age, and a quiet passing. Every possible resource should be placed at the disposal of the scientific investigation of the subject, for with knowledge will come power to relieve.
Chapter IV
The Reactions Of The Tissues Of The Body To Injuries.—Inflammation.— The Changes In The Blood In This.—The Emigration Of The Corpuscles Of The Blood.—The Evident Changes In The Injured Part And The Manner In Which These Are Produced.—Heat, Redness, Swelling And Pain.—The Production Of Blisters By Sunburn.—The Changes In The Cells Of An Injured Part.—The Cells Which Migrate From The Blood-Vessels Act As Phagocytes.—The Macrophages.—The Microphages.—Chemotropism.—The Healing Of Inflammation.—The Removal Of The Cause.—Cell Repair And New Formation.—New Formation Of Blood-Vessels.—Acute And Chronic Inflammation.—The Apparently Purposeful Character Of The Changes In Inflammation.
Injury and repair have already been briefly considered in their relation to the normal body and to old age; there are, however, certain phenomena included under the term inflammation which follow the more extensive injuries and demand a closer consideration than was given in Chapter II. These phenomena differ in degree and character; they are affected by the nature of the injurious agent and the intensity of its action, by the character of the tissue which is affected and by variations in individual resistance to injury. A blow which would have no effect upon the general surface of the body may produce serious results if it fall upon the eye, and less serious results for a robust than for a weak individual.
Most of the changes which take place after an injury and their sequence can be followed under the microscope. If the thin membrane between the toes of a living frog be placed under the microscope the blood vessels and the circulating blood can be distinctly seen in the thin tissue between the transparent surfaces. The arteries, the capillaries and veins can be distinguished, the arteries by the changing rapidity of the blood stream within them, there being a quickening of the flow corresponding with each contraction of the heart; the veins appear as large vessels in which the blood flows regularly (Fig. 11). Between the veins and arteries is a large number of capillaries with thin transparent walls and a diameter no greater than that of the single blood corpuscles; they receive the blood from the arteries and the flow in them is continuous. The white and red blood corpuscles can be distinguished, the red appearing as oval discs and the white as colorless spheres. In the arteries and veins the red corpuscles remain in the centre of the vessels appearing as a rapidly moving red core, and between this core and the wall of the vessels is a layer of clear fluid in which the white corpuscles move more slowly, often turning over and over as a ball rolls along the table.
If, now, the web be injured by pricking it or placing some irritating substance upon it, a change takes place in the circulation. The arteries and the veins become dilated and the flow of blood more rapid, so rapid, indeed, that it is difficult to distinguish the single corpuscles. In a short while the rapidity of flow in the dilated vessels diminishes, becoming slower than the normal, and the separation between the red and white corpuscles is not so evident. In the slowly moving stream the white corpuscles move much more slowly than do the red, and hence accumulate in the vessels lining the inner surface and later become attached to this and cease to move forward. The attached corpuscles then begin to move as does an amoeba, sending out projections, some one of which penetrates the wall, and following this the corpuscles creep through. Red corpuscles also pass out of the vessels, this taking place in the capillaries; the white corpuscles, on the other hand, pass through the small veins. Not only do the white corpuscles pass through the vessels, but the blood fluid also passes out. The corpuscles which have passed into the tissue around the vessels are carried away by the outstreaming fluid, and the web becomes swollen from the increased amount of fluid which it contains. The injured area of the web is more sensitive than a corresponding uninjured area and the foot is more quickly moved if it be touched. If the injury has been very slight, observation of the area on the following day will show no change beyond a slight dilatation of the vessels and a great accumulation of cells in the tissue.
Everyone has experienced the effect of such changes as have been described in this simple experiment. An inflamed part on the surface of the body is redder than the normal, swollen, hot and painful. The usual red tinge of the skin is due to the red blood contained in the vessels, and the color is intensified when, owing to the dilatation, the vessels contain more blood. The inflamed area feels hot, and if the temperature be taken it may be two or three degrees warmer than a corresponding area. The increased heat is due to the richer circulation. Heat is produced in the interior of the body chiefly in the muscles and great glands, and the increased afflux of blood brings more heat to the surface. A certain degree of swelling of the tissue is due to the dilatation of the vessels; but this is a negligible factor as compared with the effect of the presence of the fluid and cells of the exudate.[5] The fluid distends the tissue spaces, and it may pass from the tissue and accumulate on surfaces or in the large cavities within the body. The greatly increased discharge from the nose in a "cold in the head" is due to the exudation formed in the acutely inflamed tissue, and which readily passes through the thin epithelial covering. Various degrees of inflammation of the skin may be produced by the action of the sun, the injury being due not to the heat but to the actinic rays. In a mild degree of exposure only redness and a strong sense of heat are produced, but in prolonged exposure an exudate is formed which causes the skin to swell and blisters to form, these being due to the exudate which passes through the lower layers of the cells of the epidermis and collects beneath the impervious upper layer, detaching this from its connections. If a small wad of cotton, soaked in strong ammonia, be placed on the skin and covered with a thimble and removed after two minutes, minute blisters of exudate slowly form at the spot.