At the head of all stimulants stands oxygen, concerning which, for further illustration, we shall quote the following passage from Dr. Anstie:
"It needs but a glance at the vital condition of different populations in any country to arrive at a tolerably correct idea of the virtues of oxygen as a promoter of health and a curer of disease. If we compare the physical condition of the inhabitants of a London alley, an agricultural village, and a breezy sea-side hamlet, we shall recognize the truth of the description which assigns to it the same therapeutic action as is exercised by drugs, to which the name of stimulant seems more naturally applicable than to such a familiar agent as one which we are constantly breathing in the common air. A child that has been bred in a London cellar may be taken to possess a constitution which is a type of all the evil tendencies which our stimulants are intended to obviate…. It is highly suggestive to find that that very same quiet and perfect action of the vital functions, without undue waste, without pain, and without excessive material growth, is precisely what we produce, when we produce any useful effect, by the administration of stimulants, though, as might be expected, our artificial means are weak and uncertain in their operation, compared with the great natural stimulus of life."[13]
Stimulus implies no undue exaltation of the activity of any part of the organism. In complete health all parts of the body should work together in unhindered co-operation. Any undue exaltation of a particular function—excessive brain-action, excessive muscular-nutrition, excessive deposit of fat—is a symptom of lowered life, in which the co-ordinating control of the whole system over its several parts is diminished. Stimulus, on the other hand, implies an increase of the co-ordinating and controlling power. Dr. Anstie therefore recommends that the word "overstimulation" be disused, as unphilosophical and self-contradictory.
In yet one further particular, current notions need to be rectified before we can proceed. In no case is the action of a stimulant followed by a depressive reaction. This seems at first like a paradox. Physiologists have in times past maintained the contrary; and some have even ventured to apply to the phænomena of stimulation the dynamic law that "action and reaction are equal and opposite." But in physiology we shall not be helped much by the theorems of mechanics. In no case is the stimulus followed by any other "recoil" than that which is implied in the mere gradual cessation of its action, just as in the case of food which has been eaten, assimilated, and used up. We quote the following from Dr. Anstie:—"We often hear the effects of strong irritation of the skin, or the mucous surfaces, quoted as an example of the way in which action and reaction follow each other. The immediate effect of such treatment (it is said) is to quicken the circulation and improve the vital condition of the part, but its ultimate result is a complete stagnation of the vital activities in the irritated tissues. The real explanation of the matter is, however, very different. Mild stimulation of the skin (as by friction, warm liniments, &c.) has no tendency to produce subsequent depression; nor has mild stimulation of the mucous membranes (as by the mustard we eat with our roast beef). But the application of an irritant strong enough to produce a morbid depression at all, produces it from the first. Thus the cantharidine of a blister has no sooner become absorbed through the epidermis than it at once deprives a certain area of tissue of its vitality to a considerable extent, as is explained by the researches of Mr. Lister…. Here is no stimulation first and depressive recoil afterward, but unmitigated depression from the first."[4] "What has been commonly spoken of as the recoil from the stimulant action of a true narcotic is, in fact, simply the advent of narcosis owing to a large impregnation of the blood with the agent after the occurrence of stimulation, owing to a small one. Thus a man drinking four ounces or six ounces of brandy gradually, has not in reality taken a truly narcotic dose till perhaps half the evening has worn away; previously to that he has not been 'indulging in narcotism' at all; nor, had he stopped then, would any after depression have followed, for he might have taken no more than two ounces of brandy, equal perhaps to one ounce of alcohol. But he chose to swallow the extra two ounces or four ounces, thus impregnating his blood with a narcotic mixture capable of acting upon nervous tissue so as to render it incapable of performing its proper functions. The narcosis has no relation to the stimulation but one of accidental sequence. This is proved by the fact that in cases where a narcotic dose is absorbed with great rapidity, no signs of preliminary stimulation occur."[15]
This disposes of the popular objection to stimulants—based upon the long-exploded theories of vitalistic physiology[16] —that every stimulus is followed by a reaction. It is seen that when a man feels ill and depressed after the use of alcohol or tobacco, it is because he has not stimulated but narcotized himself. We challenge any person, not hopelessly dyspeptic, to produce from his own experience any genuine instance of physical or mental depression as the result of a half-pint of pure wine taken with his dinner,[17] or of one or two pipes of mild tobacco smoked after it.
Let us not, however, indulge in sweeping statements. We have expressed ourselves with caution, but a still further limitation needs to be made. There are a few persons who are never stimulated, but always poisonously depressed, by certain particular narcotics. There are a few persons—ourselves among the number—in whom a very temperate dose of coffee will often give rise to well-defined symptoms of narcosis. There are others in whom even the smallest quantity of alcoholic liquor will produce giddiness and flushing of the face. And there are still others upon whom tobacco, no matter how minute the dose, acts as a narcotic poison. But such cases are extremely rare; and it is needless to urge that such persons should conscientiously refrain, once and always, from the use of the narcotic which thus injuriously affects them. Our friendly challenge, above given, is addressed to the vast majority of people; and thus limited, it may be allowed to stand.
We have now defined a narcotic; we have seen that narcotics, in certain doses, will act as stimulants, and we have defined a stimulant. Until one's ideas upon these points are rendered precise, there is little hope of understanding the ordinary healthy action either of tobacco or of alcohol. But the reader who has followed us thus far will find himself sufficiently prepared for the special inquiry into the stimulant effects of these substances. Confining ourselves, for the present, to tobacco, we shall find that by assisting the nutritive reparatory process, it conforms throughout to the definition of a true stimulant.
What do we do to ourselves when we smoke a cigar or pipe? In the first place, we stimulate, or increase the normal molecular activity of, the sympathetic system of nerves. By so doing we slightly increase the secretion of saliva, and of the gastric,[18] pancreatic, and intestinal juices. We accomplish these all-important secretory actions with a smaller discharge of nerve force: we economize nerve force in digestion. And by this we mean to say that we perform the work of digesting food just as well as before, and still have more of the co-ordinating and controlling nerve-power left with which to perform the other functions of life. Thus at the outset tobacco exhibits itself as an economizer of life. Such is the inevitable inference from its stimulant action on the sympathetic. From the distribution of the sympathetic fibres, we deem it a fair inference that the bile-secreting function of the liver is also facilitated; but of this there is less direct evidence.[19] We can now understand why a pipe or cigar dissipates the feeling of heaviness ensuing upon a dinner, or other hearty meal; and when we recollect how instant is the relief, we can form some notion of the amount of nerve-force which is thus liberated from the task of digestion. We are thus also reminded of the hygienic rule that smoking must be done after eating, and not, in ordinary cases, upon an empty stomach. If we smoke when the stomach is empty and quiescent, the stimulated secretion of the alimentary juices is physiologically wasteful; and, moreover, the much more rapid absorption of nicotine by the blood-vessels increases the liability to narcotic effects. It is upon this very principle that the same amount of wine may stimulate at dinner, but narcotize when taken in the forenoon.
Thus far we find tobacco to be a friend and not an enemy. Now, in the second place, when we smoke, we stimulate the medulla oblongata, and through this we send a wave of stimulus down the pneumogastric nerve, and this makes the heart's action easier. One of the earliest stimulant effects of tobacco to be noted is the slightly increased frequency and strength of the pulse.[20] A narcotic dose produces quite the opposite effect. It begins by greatly increasing the frequency while diminishing the strength, so as to make a feeble, fluttering pulse; and it ends by reducing the frequency likewise. After some years of temperate smoking we accidentally felt, for the first time, the narcotic effects of tobacco. Eight or nine cigars (large twenty-cent ones, such as Mr. Parton delights in the recollection of) smoked consecutively while taking a cold midnight drive, were followed by unmistakable symptoms of narcosis. Along with the muscular tremour of the stomach, much more acute than that of ordinary nausea, it was observed that the pulse, normally strong and regular at 80, had been reduced to 69, and was feeble and flickering. Similar, no doubt, are the symptoms which ordinarily worry the novice, in whom acute narcosis is liable to result from the lack of skill with which he draws in too large a quantity of the narcotic constituents of his cigar. The effects of tobacco, through the medulla and pneumogastric, upon the heart, are among its most notable effects. A dose of pure nicotine stops the heart instantly, a narcotic dose interferes with its action, but a stimulant dose facilitates it. The same results are attainable by means of electricity.[21] A powerful current through the pneumogastric of a frog or rabbit will stop the heart, a less powerful current will slacken it, a slight current will somewhat accelerate it. Emotional effects are precisely similar. Sudden overwhelming joy or sorrow may operate as a true narcotic, arresting the heart's contractions, while steady diffusive pleasure always facilitates them.
The stimulant action of tobacco upon the heart is precisely the same as that of sunlight, which, by inciting the nervous expanse of the retina, indirectly strengthens and accelerates the pulse. So far as the circulation is concerned, there is no difference between the two. The one stimulus may indeed be popularly called "natural," while the other is called "artificial," but such a distinction is physiologically meaningless. The molecular action is the same and the consequences to the organism are the same in both cases. The heart's normal action being facilitated, the blood is poured more vigorously through every artery, every vein, and every network of capillaries. Every tissue receives with greater promptness its quota of assimilable nutriment. And, the web-like plexuses of nerve-fibres distributed throughout the tissues being simultaneously stimulated, the work of nutrition goes on with enhanced vigour and efficacy. Nor is it possible for the excreting organs to escape the influence. Lungs, skin, and kidneys must be alike incited; and the removal from the blood of noxious disintegrated matters, the products of organic waste, is thus hastened.