The organic properties of the skin are also frequently put into action by sympathies. The sweat on the skin is suppressed in a moment, if a cold body is taken into the stomach. The entrance of teas into this viscus, and an increased cutaneous exhalation, are two phenomena that take place almost at the same instant; so that we cannot refer the second to the absorption of the drink, then to its passage into the black blood through the lungs, and afterwards into the red blood. The production of sweat is then here analogous to its suppression in the preceding case; it resembles that of fear, and that of phthisis in which the lungs being affected act upon the skin. Shall I speak of the innumerable varieties of this organ in diseases, of its dryness, its moisture, its copious sweats, &c. phenomena for the most part sympathetic, and which arise from the relations which connect this sound organ with the diseased parts? I have pointed out those which exist between it and the mucous surfaces. The membrane of the stomach is the one with which it especially sympathizes. The digestive phenomena are a proof of this. It would be necessary to treat of all diseases in order to speak of the sympathetic influences exerted upon the skin. These influences are often chronic. How in many organic diseases, do different tumours form upon the skin? Precisely as petechiæ, miliary eruptions, &c. are produced in acute fevers; the difference is only in the duration of the sympathetic phenomena.
Animal and sensible organic contractility cannot be evidently put into action in the passive sympathies of the skin, since it is not endowed with these properties.
Active Sympathies.
The four classes of cutaneous affections of which we have spoken, occasion many sympathetic phenomena, the following are some of them.
1st. Whenever the papillæ are strongly excited, as in the tickling of very sensitive people, various organs feel it sympathetically; sometimes it is the heart; hence the syncopes that then take place; sometimes it is the stomach; thus I knew two persons who could be made to vomit by tickling them; sometimes it is the brain, as when in very irritable people, tickling is carried so far as to produce convulsions, which is not very rare in nervous women. Who is ignorant of the influence which the organs of generation receive from the skin, when stimulated in different parts?
Physicians are often astonished at the extraordinary effects which some mountebanks produce in the economy, who know how to profit by their knowledge of the cutaneous sympathies produced by tickling. But why should we be more astonished at these phenomena, than at the vomitings produced by an affection of the womb, at the diseases of the liver arising from an injury of the brain, or at hemicrania the seat of which is in the gastric viscera? The only difference is that we can in the first instance, produce to a certain extent those sympathetic phenomena, which we only observe in the other. Why do we not oftener make use in medicine of the influence which the skin when tickled exerts upon the other organs? In hemiplegia, in adynamic, ataxic fevers, &c. who knows if the excitement of the sole of the foot, which is so sensible, as every one knows, if that of the hypochondrium, which is not less so in some people, &c. would not be better, if repeated ten or twenty times a day, than the application of a blister, the irritation of which soon passes off? Besides you would never obtain by a blister, rubefacients, &c. means which act as much and more upon the organic than the animal sensibility, an effect as striking, an affection as general in the sensitive system, as by the tickling of certain parts, a means, which acting only upon this last species of sensibility, produces phenomena exclusively nervous; whilst the exhalant system and the capillary with red blood are especially affected by the others. Certainly there are cases in which one of these means is preferable to the other. I propose to ascertain these cases.
We have not yet sufficiently analyzed the different kinds of excitement in diseases; we have not endeavoured to profit enough by what observation has taught us, upon the sympathies we can produce at will. Might we not however say, that nature has established certain relations between very remote organs, that we may be able to make use of these relations in our means of cure? The charlatan, who employs external tickling for certain nervous affections, is often more rational, without knowing it, than the physician with all his pharmaceutical means.
2d. Whenever the cutaneous exhalants or the external capillary system from which they arise, are affected in any manner, many other parts feel it, and this is a second order of the active sympathies of the skin. Here are referred a great number of phenomena, of which the following are a part.
A bath which acts upon the skin during digestion, affects sympathetically the stomach, and disturbs this function. When this viscus is agitated by spasmodic motions, oftentimes the influence which it receives from it suddenly calms it, and brings it to its ordinary state. Not long since in my evening visit at the Hôtel Dieu, I saw a woman who was vomiting continually from a sudden suppression of her catamenia. I directed sedatives which were useless. The next evening she was in the same state; I had her put into a bath; every thing was calmed the moment she came out of it, and yet the catamenia did not return. Few organs are more dependant on the skin than the stomach.
The action of cold upon the cutaneous organ produces many sympathetic effects, especially when this action takes place while we are sweating. The term repercussion of transpiration is not proper to express what then takes place; it gives a very inaccurate idea. Let us suppose that a pleurisy arises from cold suddenly applied, the following is what happens; the organic sensibility of the skin being immediately altered, that of the pleura is sympathetically altered. By it the exhalants become in relation with the blood; they admit it instead of the serum which they before received, and inflammation supervenes. Thus this phenomenon is the same as that in which the application of a cold body upon the skin suddenly arrests uterine, nasal hemorrhage, &c. &c.; the result only differs. Now in this last case, no one ever supposed that there was a repercussion of fluid. The suppression of the transpiration is a thing purely accessory and foreign to the internal inflammation which takes place. When the skin sweats in summer, the vital forces are more raised by the caloric which penetrates it; in this state, it is more capable of acting sympathetically upon the forces of the other systems. Hence why all strong stimulants that act upon it are more to be feared then. It is so true that it is not the suppression of the sweat which is dangerous, but the alteration of the vital forces of the skin which sweats, that many kinds, as the sweat of phthisis, are not so injurious when they cease for a time; they are checked even with much more difficulty, because they are not produced by a cause acting immediately upon the skin. Now if there was a repercussion of the transpiration, every species of sweat that was suppressed would be injurious. We never hear of a peripneumony arising from a suppression of sweat produced by fear, rheumatism, &c. There would be then also a repercussion of mucous matter, when a pleurisy arises from swallowing a glass of cold water. Men judge only by that which is striking. The suppression of the sweat is an effect like inflammation of the pleura, but it is not the cause of it. If there was no sweat the instant the cold was applied to the skin, inflammation would nevertheless come on. In wounds of the head, with abscesses of the liver, &c. there is no repercussion of fluids.