The effort, normally present, towards warding off disease, such as for instance, the information of antibodies, the more active participation of the internal secretions, and similar activities are temporarily stimulated by the drug. By this means, the original natural disease is conquered and the physiological balance again restored. The stimulation due to the drug and the disturbance associated therewith are active for so short a period that not further disadvantage arises from them and the consequence especially peculiar to them are quickly remove.
The historical portion of our subject has been completed. Now, we are to concern ourselves with the task of investigating as to whether the principle, “Similia similibus curantur,” in its full import is justifiable or not. We must ask ourselves : Is it conceivable that a drug can produce in a healthy being a symptom complex which resembles one appearing in an illness of the same organ or even of the entire organism-an illness of the same organ or even of the entire organism-an illness due to entirely different circumstances? And further : If that is really so, how is it conceivable that a drug can cure a disease whose symptom complex so closely resembles the effect of the drug itself?.
If we proceed from the assumption that every living cell, every living tissue and organ, every living organism only exists because of the fact that in them all without exception a constant process of creation and destruction is taking place, the intensity of which is to be measured according to the rate of metabolism-if one will go further and compare this with he uniform swinging of a pendulum or the even turn of the analytical scales, one can speak with reason of a “physiological latitude” within which the life process of the individual cells, organs, and organisms play its part.
A foreign factor that in some way influences the even swinging of the pendulum, the uniform turn of the scales, must logically produce changes in the normal course of both of the mechanical appliances. In like manner does each extraneous disturbing influence act on the life process of any organ. It is force out of the normal physiological latitude of its life activity.
The foreign factor has in such a case acted as a “stimulus.” The deviation from the normal physiological latitude corresponds to the reaction of the affected organ to this stimulus.
We draw from the changes in the behavior of the organ and the organism-changes due to the effect of the stimulus, the double conclusion : First and above all, that a reaction occurred-that the factor serving as a stimulus had the power within itself to start a reaction-and Second, that the organ or the organism under discussion was in a condition to react.
Granted that the conditions necessary for the development of a reaction due to stimulation are present, how should this reaction express itself? To begin with, let us choose a very simple and easily comprehensible example. Suppose we take a freshly prepared nerve-muscle preparation of a frog, similar to that used by the physiologist for detection and demonstration of certain reactions which the muscle shows when the nerve which innervates it, is stimulated.
Experience has taught that it is a matter of indifference with what one stimulates the nerve in order to always obtain the same result, i.e., a muscle contraction.
One can pinch the bare nerve with pincers or apply to it a drop of acid or alkali solution, one can irritate it with the electric current or subject it to the influence of heat or cold, the result always remains the same : the muscle contracts, assuming, of course, that neither is the nerve too severely mutilated nor has the nerve-muscle specimen lost its viability.
The explanation of the fact that the muscle always reacts in the same way when its nerve is stimulated, is simple and the reaction is a matter of course.
In want other way should a muscle portray its capacity for reacting to a stimulus communicated to it through the nerve than by contracting or, in case the stimulation increases beyond a certain limit, by means of tetanic contractions? Contracting and relaxing are the two possible ways by which the muscle, due to its peculiar construction, can display its function. It possesses no other possibilities. I wish again to emphasize the fact that it does not matter in what way or through what influence the muscle is induced to respond. THE QUALITY OF THE STIMULATING AGENT DOES NOT COME INTO QUESTION; assuming that it is at all capable of stimulating and that the muscle is in condition to react to stimulation.
As another example, instead of the nerve-muscle preparation, which is in plain sight, let us take a gland still connected with the remainder of the organism. Its physiological function is to secrete. This activity can, according to the special stimulating influence that it may be subjected to, take place more slowly or more quickly in the same space of time. The secretion itself can change with regard to its chemical composition and thereby alter its physical reaction up to a certain limit. In the same way, combinations of these different variations from the normal are possible.
If a gland be exposed to such influences as ,may have a stimulating effect upon it, then one plainly recognizes the effect of the stimulation in the changes produced in its secretory behavior. However, in the case of a gland, the relation is much more complicated than in that of the muscle-nerve preparation. In the latter, the muscle can be made to contract just as well by direct stimulation applied to the muscle as by stimulating it indirectly through the nerve. In the foregoing paragraph, we spoke, for the sake of simplicity, only of the indirect way of stimulation through the innervating nerve.
With a gland however, the conditions are such that we can cause disturbances in the normal secretion-in the physiological latitude of the gland function-not only through the stimulation of the secretory nerve fibres alone but also by changing the blood supply of the organ, and finally also by factors of which we may assume that they act solely upon the secreting elements- the gland cells themselves.
In an organ the construction of which is so complicated as that of a gland, in which secreting cells, nerves, blood and lymph vessels, connective tissue, and occasionally also unstriated muscle are combined in a whole, each element of which can by itself or also in manifold combination with the other glandular elements come under the stimulating influence, it is not always possible to say with certainly which was the first of these to react when the gland was subjected to the stimulus.
But : assuming that there is any possibility whatever of reaction between the gland as a whole and the stimulating agent; the character of the reaction is always the same! As we do not know beforehand which element of the gland will react, it is reasonable to expect because of the complicated structure of the organ that there should result a variation in the details of the reaction according to the nature of the case. The secretions may flow more profusely or more scantily, it may be more dilute or less dilute, its chemical composition and there with also its specific effectiveness may be changed. The principal fact which concerns us, remains unaffected by these details. When a gland is effectively stimulated, we observed changes in secreting function.
The explanation of why this is as it is and not otherwise, is the same as in the case of the nerve-muscle preparation : the gland is just as restricted in its power to respond to an effective stimulation as is the muscle; for both are governed solely by their anatomical and histological structure and their physiological function. This holds good for all organs, whatever they may be called and however they may be constituted; consequently, for the organism as a whole.
Among the stimuli which are of interest to us and with which we are enabled to direct the activity of a particular organ or the reaction of the organism as a whole along a given course, belong the different means which we employ in our therapeutical procedure. Drugs, as such, compose by far the greatest portion of these. They do, however, compose by far the greatest portion of these They do, however, compose, as just mentioned, a part only. All other measures, the use of hydro and electrotherapy, radiation with roentgen rays or quartz lamps, application of he and cold, not to forget such factors as associate themselves with nutrition in a favorable and an unfavorable sense: all of these are to be given equal value in the solving of the problem.
We have seen: the quality of the stimulus is of no particular importance, granted that in a given case, it is able to bring about a reaction at all. It is quite a different matter, however, as regards quantity-the intensity of the stimulation. This plays a very great and important part. Its undervaluation and the lack of attention given to it, leads undoubtedly to therapeutic errors and failures. Rudolph Arndt was the first to show the far-reaching importance of the intensity of the stimulation for every physiological process.
