There is not one thousandth of an inch of our body surface which does not swarm with innumerable bacteria, and as soon as the continuity of our skin is severed, as by a small wound, they immediately invade our tissues and attack us. Happily we are not without means of defense. Our organism is so well arranged that, as soon as a foreign body enters which might become injurious, a kind of police organization comes into action, and the leucocytes, like policemen, arrest the bacilli, and render them harmless by eating them up. This is phagocytosis, first described by the great French investigator, Metschnikoff. And so marvelously arranged is our body, that there are also special substances, the alexins (Buchner), which aid the leucocytes, and the opsonins, which first act upon the bacteria, so as to make them more digestible for the leucocytes.
To make the bacilli still more sensitive to the influence of the alexins there are the agglutinins, observed by Bordet, and by Gruber and Durham, which immobilize the microbes, and thus aid the phagocytes and alexins in the performance of their task.
The leucocytes are formed in the lymphatic tissues, especially the lymph glands and spleen. Thence they circulate through the body and offer opposition to the microbes and other foreign bodies which they meet on their way. The red blood-corpuscles of the adult are formed chiefly in the bone marrow.
The lymphatic glands play an important rôle, not only as the birthplace of leucocytes, but also in that they are able to arrest noxious substances, such as microbes, and keep them from entering the circulation. That the lymphatic structures are able to protect us against bacillary infection can be shown by the swelling of the spleen in infectious diseases,—such as typhoid fever, malaria, etc.
The tonsils are also of some importance for our protection against harmful substances. They become inflamed in various infectious diseases—such as scarlet fever, measles, acute nephritis, etc. Their great value may best be shown by the fact that not infrequently, after total extirpation of both tonsils, a generalized eruption has been observed. Thus we must always seriously reflect before advising the extirpation of these important organs, the rôle of which as sentinels is shown by their anatomical position on either side of the entrance for the most indispensable elements of our life: air and food. Unless frequent inflammation, and possibly irritative nephritis, demand an operation, it would be better not to undertake it. Even if it is done, the glands should never be entirely removed.
A great number of microbes enter our system through the mouth with the air and food, but happily they are antagonized by the saliva and the gastric juice, which are able to destroy a large number of these obnoxious invaders. Like the ductless glands, the lymphatic glands are closely connected with one another, and thus changes in one of these glands are apt to be followed by changes in the others. Hence we can see how a lymphatic structure contained in the intestine,—the appendix,—can often become inflamed after previous inflammation of the tonsils. As is well known, the appendix shows great similarity in its histological structure to the tonsils, so much so that some call it an intestinal tonsil. Several authors have drawn attention to the fact that appendicitis has often been observed after tonsillitis, and Delcour has written a monograph in which he attributes appendicitis, indirectly, to thyroid degeneration,—e.g., congenital myxœdema. Adenoid vegetations are always accompanied by chronic pharyngitis and tonsillitis, which bring about appendicitis. And since adenoid vegetations are an expression of thyroid deficiency, Delcour attributes appendicitis to a deficient thyroid. We are not prepared to accept Delcour’s statement, as there are cases of adenoid vegetations without a deficient thyroid. However, as we have personally observed, chronic nasal catarrh and tonsillitis are very frequent in persons subject to appendicitis. The appendix is an important lymphoid organ and, if possible, it should be preserved.
As I have already shown in a previous communication,[168] the lymphatic glands stand in very close relation to the thyroid gland. In diseased conditions of the thyroid we find, as a rule, enlarged lymphatic glands, as in Graves’s disease, myxœdema, cretinism, acromegaly, and also in diabetes. The thyroid seems to exert a great influence, not only upon the lymphatic glands, but also on the blood-corpuscles. The red blood-corpuscles are diminished after extirpation of the thyroid, as also in myxœdema, as well as in old age. On the other hand, they can be increased very considerably by thyroid feeding. The white blood-corpuscles are also influenced by the thyroid, for, after extirpation of the thyroid, their number is at first increased and later diminished. Very important is the discovery of Mlle. Fassin[169] (in the laboratory of the University of Liège, Belgium), who found a diminution in the production of alexins after extirpation of the thyroid, thus confirming what Sajous had pointed out four years earlier. According to Sir Almroth Wright, the discoverer of opsonins, the production of these bodies also depends upon the internal secretions. We have seen that Sajous has shown (a fact confirmed by others since) that opsonins are mainly composed of thyroid secretion.
Thus we see that the production of antitoxins is greatly under the influence of the thyroid, which governs the processes of phagocytosis, and thus powerfully helps in the defense of our system.
Besides microbes, we introduce into our body a large number of harmful products through food and drink (stimulants). Many toxic substances are formed by the decomposition of food, and also in the processes of metabolism in the tissues. We are protected against these substances by certain organs which destroy them (as the thyroid, parathyroids, and liver), and by other organs which eliminate them (as the kidneys, the skin, and the intestines). When these organs are all working well, we may get rid of these products and not be affected by them; but in old individuals it is different, as their protective and eliminative organs have more or less degenerated. Then these substances are not destroyed entirely, nor wholly eliminated. They are retained, and cause the condition of auto-intoxication.
It is very difficult to prove definitely by experiments, that there really exists such a condition as auto-intoxication; but, practically, its existence cannot be denied. We note after changes in the above-named organs, when their functions are in abeyance, signs of intoxication in a patient, which include headaches and other nervous symptoms, with a haggard and colorless face. After a good movement of the bowels, perspiration, and abundant diuresis, we see a great change for the better. Thus, even if scientific experiments which are made on small animals do not strictly confirm the existence of auto-intoxication, the great improvement in our condition after improved elimination speaks very strongly for its existence. Therefore, to prevent such a condition, we must do our best to keep these organs in good working order. In the succeeding chapters we shall consider in detail the protective and eliminative functions of these organs, and the possibilities of their improvement by hygienic and therapeutic measures.