Prop. IV.—That some few remedial agents act locally on the mucous surface, either before absorption, or without being absorbed at all. That they are chiefly as follow:— (continued 3)

It is not to be wondered at that in many cases of deeply-rooted blood-disease, complicated perhaps with anæmia, structural change of organs, disordered assimilation, and various nervous symptoms, all remedies alike should prove useless. So that the experience of many practitioners, thus frequently disappointed in their hopes of a cure, has led them to question altogether the efficacy of Iodine in Scrofulous disorders. But it is generally allowed that it is more beneficial in such cases than any other medicine, and is the only remedy which is universally applicable in Scrofula. If this be true, it follows that it must have a special power over this blood-disease.

Burnt sponge, and the ashes of a seaweed, the Fucus vesiculosus, both of which contain Iodine, have been used in Scrofula from very early times. But it was not until the present century that Iodine was discovered, and its efficacy in Scrofula, particularly in the cure of Goitre, pointed out by Dr. Coindet of Geneva. After this it came to be generally applied in all Scrofulous cases, and was especially recommended by M. Lugol in France, as a specific for such maladies.

When given for some time, Iodine has the effect of impoverishing the blood, like Mercury and many other Catalytics, diminishing in it the amount of Fibrine. All remedies which do this favour absorption. This effect is obviously connected with the alteration in the blood, and there is no reason to suppose that any special stimulant action is exerted on the absorbent vessels. Those Catalytics which favour absorption are not all useful in the same cases, but some are most useful in one disorder, some in another. Thus they must exert a special action over morbid poisons; an action which is altogether distinct from the influence over absorption, although by this latter they may be able to cause the disappearance of effused products, and of tumours produced in various ways.

In some rare cases Iodine has even been known to cause the absorption of healthy glands, as the mammæ and testicles.

Iodine and Iodide of Potassium, when successful, do not merely cause the disappearance of scrofulous tumours, but further meet and neutralize the poison which is working in the system, and effect a more or less permanent cure. This could hardly be done by a remedy which had only the power of promoting absorption.

It seems that some systems are able to bear with impunity very large doses of Iodide of Potassium. I once met with a medical man who denied its power altogether, because he himself had frequently taken a scruple, and sometimes a drachm at a time, without any effect. Other men are readily affected by very small quantities, and quickly experience the symptoms of Iodism. It is probable that in the former case the medicine is very quickly eliminated by the kidneys; but that in the latter it remains in the system for some time.

The Iodide of Iron is a most useful medicine for scrofulous children, who commonly suffer under Anæmia, as it combines a Chalybeate with an Antiscrofulic action.

Bromine and Chlorine resemble Iodine in their Antiscrofulic effects. It is said that Scrofula and Consumption are unknown among the workmen in bleaching factories, where Chlorine is being constantly inhaled. Thus it has been strongly recommended that diluted Chlorine should be constantly inhaled by consumptive patients. It is probable that part of the efficacy of sea-side air and sea-voyages in scrofulous cases may be due to the free Chlorine which is given off in small quantities from the salt water of the ocean. The powers of Iodine and Bromine are shared by their compounds; and probably Chlorine is no exception to this rule. The bad consequences which follow the omission of common salt from the food, are sufficient to show that this substance has a beneficial action on the blood. Probably large doses of this article of diet would be found advantageous in Scrofulous disorders.

It is easy to recognise such an action as that of Iodine in Scrofula, but it is almost impossible to invent a satisfactory explanation for it.

Potash, free or carbonated, is another remedy of considerable importance in Scrofulous diseases. It is possibly one of those Catalytics which exert a simple chemical influence. It may act by holding in solution fibrinous and fatty matters, and preventing their abnormal deposit in a crude form in the shape of tubercular matter. It may also be found useful in cases of Syphilis, when aggravated by a previously existing strumous tendency, and where a course of Mercury cannot be safely prescribed.

Small doses of Mercury, as an alterative, are often efficacious in scrofulous constitutions. They appear to act simply by stimulating the torpid liver to a performance of its proper function.[40] (Vide page 144.)

Potash has been used as a prophylactic against Consumption. The efficacy of Cod Oil in this disease has been explained by some as depending on the Iodine which it contains in small quantities. I do not consider this explanation to be the correct one. (Vide Cod Oil, in Chap. IV.)

Ord. IV. Antiarthritics.

In this order are included some blood-medicines which exert a direct influence over certain disorders which depend on some fault in the complicated processes of assimilation and nutrition. The chief of these diseases are, Diabetes; Oxaluria; Lithic deposit in the urine; and the true Arthritic disorders, i.e., Gout and Rheumatism. Most of those blood diseases which cannot be clearly traced to the introduction of a poison from without may be arranged under this head, and appear to be curable by the same set of remedial agents.

There are certain processes always going on in the blood, whose continuance in the right direction is essential to health. When one of these processes is disturbed, it does not generally cease, but it goes on then in a wrong direction.

The natural processes result, on the one hand, in the preparation of fit and proper nutriment out of the materials of the digested food, for the growth and support of the several tissues and functions; and, on the other hand, in the gradual change and conduction out of the body of the products of the waste of those tissues. But when any process goes on in a wrong direction, it results in the formation of various products different from those which are required, and which the kidneys and other glands are at length called upon to excrete from the system. The result is that the general health is more or less seriously impaired.

There is also another way in which these diseases are not unfrequently caused. A natural process may stop at a certain point, and go no further. The material formed at that stage remains as it is. It is not wanted; it is morbid; and it also is excreted from the body. It is possible that these errors in the assimilative processes may sometimes arise in the first instance from a deficiency in the blood of some substance whose influence was necessary to the proper conduct or control of the natural series of changes. Some of these conducting materials may be formed by the liver; for it is found that these disorders are very commonly connected with an impairment of the function of that organ. Thus Mercury, which restores the secretion of the liver, is often useful in Arthritic disorders; as also is Quinine, which has already been shown to have a peculiar relation to liver diseases.

But these disorders, however they may first originate, consist in an active morbid process of one kind or another; and the surest way of counteracting this process, or of diverting it into a right direction, is by the employment of one of the Catalytic medicines contained in this order. Some stages of these diseases are attended with a want in the blood of some of its ordinary constituents; which condition may be relieved by the supply of a Restorative remedy.

Thus in this group of disorders three kinds of medicines may be employed, which tend in various ways to improve the condition of the blood.

Acids and Alkalies are sometimes needed, and act on the Restorative principle. The true Antiarthritics are those medicines which are employed on the Catalytic plan, to meet and neutralize the morbid material or process in the blood. And sometimes Eliminatives are made use of, which seem, by acting on the secretions of the skin, kidneys, or bowels, to be able to rid the blood of an unnatural product. Thus Guaiacum and Salines are employed in Rheumatism, and Purgatives in Gout.

These two joint affections are most characteristically under the influence of Catalytic remedies. Diabetes and Lithiasis are more under the control of Restoratives than the others.

The medicines composing this fourth order of Catalytics have been already enumerated.

That Colchicum tends in some way to neutralize in the blood the poison of Gout, and to a less degree that of Rheumatism also, is generally admitted, although various theories have been adopted to explain this action. (Vide Chap. IV. Art. Colchicum.)

In Oxaluria, the employment of Nitric acid as a remedy was first recommended by Dr. Prout. Dr. Golding Bird advised the substitution of Nitro-hydrochloric acid, which has proved to be a most valuable remedy, not only in this disorder, but also in some cases of lithic deposit. The Oxalate of Lime rarely occurs alone in the urine; there is generally along with it some Urate of Ammonia. The causes of the two deposits appear to be in some way connected. So also are the remedies similar. Dr. G. Bird has found Colchicum to be of signal service in cases of lithic deposit in the urine; and has proved the same medicine to be efficacious in Oxaluria.

I will now attempt to show how the action of these medicines may admit, on certain grounds, of a chemical explanation. There are very few Catalytic actions in which such an explanation can be attempted, but a degree of plausibility appears to attach to the idea in this case, though it cannot of course be considered to be susceptible of more than a demonstration of probability.

I have already said that in all the disorders now under consideration there are certain morbid constituents in the blood which have been recognised by chemical tests. In Diabetes there is an excess of grape-sugar formed in the blood, and excreted from it in the urine. In Rheumatism we have a painful joint affection, attended with a great development of acid in the system; and this acid, which we have many reasons for supposing to be lactic acid, is occasionally excreted by the skin. In Gout we meet with another Arthritic affection, in which there is urate of soda in the blood, and an excess of uric acid and urea in the urine. A simple excess of uric acid in this secretion constitutes Lithiasis. There is an obvious but ill-understood connexion between the last two disorders, and, indeed, between all those of which we are treating. In Oxaluria we have an abnormal formation of oxalic acid in the blood, which is excreted in combination with lime, for which base it has a great affinity. In oxalic urine there is generally an excess of urea, as I have found in many cases.

Now it seems to me that all these disorders are capable of being explained by reference to the series of changes in the blood which are associated with the respiratory process. (Vide Liebig's Anim. Chem., part i. p. 133; Dr. B. Jones' Anim. Chem., pp. 20, 118.)

It is the general opinion of modern chemists, that before the starch of the food can be applied to the maintenance of the animal heat, for which office it is chiefly intended, it passes through a series of chemical changes. First, assuming two equivalents of water, it becomes grape-sugar; next, this changes into lactic acid, which is isomeric with it; and this again combines with twelve atoms of oxygen, to form carbonic acid and water. This last change is a process of combustion, and thus produces heat. The oxygen needed for it is absorbed from the air by the pulmonary mucous membrane, and the carbonic acid formed passes out of the blood at the same surface.

Liebig was the first to point out the connexion between these changes and the phenomena of Diabetes. It is clear that if the process were to stop at the formation of grape-sugar, the condition of blood that exists in Diabetes would result. This sugar cannot be put to any use, and is excreted as fast as formed. There is an excess of urea in the whole quantity of urine passed in the day; probably because the nitrogenous food and tissues are undergoing combustion instead of the starch. Before becoming grape-sugar, starch undergoes a transitional change into Dextrine, a gummy insipid substance which has the same composition as itself. It seems that the process may even stop as early as this, and that by this stoppage another analogous disease may be produced, i.e. Diabetes insipidus. The common Diabetes is called D. mellitus. (Vide Jones' Anim. Chem. p. 120.)

If it were clearly proved that the acid of Rheumatic fever is lactic acid, then this affection might evidently be produced by a stoppage of the process at the next stage. Lactic acid has been formed; but, for some reason unknown, it is not oxidized into carbonic acid. Urea and uric acid are in excess in the urine, from the cause alleged above.

But suppose some of the sugar to be oxidized prematurely, without passing first into lactic acid. By this oxalic acid would be produced, and the phenomena of Oxaluria accounted for.

These things are only alleged as possible, and for the purpose of showing that, should they be true, the action of some useful remedies might be elucidated. It is not at all unlikely that the accuracy of such ideas may be completely established by fresh discoveries at no distant time. But let us continue.

In Gout and Lithiasis there is an excess in the system of nitrogenous matter, and thus a tendency to an extra formation of urea. These conditions are often brought on, and always aggravated, by over-indulgence in animal food. Now if we may suppose that some of the lactic acid, instead of oxidizing directly into carbonic acid, oxidizes in combination with this urea which is in excess, then uric acid and water might result, as is shown below. The uric acid passes out into the urine in excessive quantity.

Should this be the case, the great affinity existing between the course and symptoms of Gout and Rheumatism would be easily explained, there being in both disorders an impediment to the proper oxidation of lactic into carbonic acid. These things may be illustrated by a diagram, showing the results which are supposed to take place when the natural process is arrested at, or diverted from, any of its stages:—

Thus, at each of the two transitional stages, we might have one diseased condition produced by an arrest of the process, and another by its deviation. These deviations and stoppages may result from a failure of some natural principle which is gifted with the control and direction of the series of transformations; or they may simply be traceable to a want of vital energy, or nervous force.

The same ideas may be more distinctly expressed by a few chemical equations.

The last equation may be thus proved at length:—

It is next to be inquired how far the theoretical explanation of these diseases which has thus been sketched out can be applicable to the matter in which we are more immediately interested, viz., the action of the Catalytic remedies used to cure them.

For the radical cure of Diabetes there is no known remedy; though some relief may be afforded by a system of dieting. (Vide Aliments.) It is supposed that what we have to do is to convert diabetic sugar, i.e. grape-sugar, into lactic acid. This acid probably exists in the gastric juice. And some such substance as Pepsin, or the decomposing Caseine in sour milk, which is capable of effecting this change out of the body, might perhaps avail us, if we could contrive to introduce it into the blood.

In Oxaluria, the best treatment consists in a course of Nitro-hydrochloric acid. This remedy is prepared by adding one part of Nitric to two of Hydrochloric acid; and is diluted considerably with water when prescribed. The Nitric acid causes the oxidation of some of the Hydrogen of the other acid, and thus sets free Chlorine gas. This is stated by Mr. Brande to go on until the liquid is saturated with this gas. The result of the presence of Chlorine is, that from the affinity of this gas for Hydrogen, by which, under certain circumstances, it is enabled to set free the Oxygen of water, this compound acid becomes the most powerful oxidizing agent known. This acid has been lately used as a remedy for Gout and Rheumatism, in spite of the acid state of the fluids in those cases; and I believe it to be a very valuable medicine in both of these disorders. A simple mineral acid would do no harm in both instances. The Nitro-hydrochloric acid must operate in some special way.

It is probable that its action may depend upon its oxidizing power.

In Oxaluria it might cause the oxalic acid to be oxidized into carbonic acid, and thus restore health. Thus:

In Rheumatic fever, where we have supposed that lactic acid is formed as it should be, but then stops short, and proceeds no further, the oxidizing agent may convert this into carbonic acid.

In Gout and Lithiasis, where there seems to be an excess of nitrogen in the system, and thus more oxygen is needed to restore the equilibrium, I have supposed that lactic acid and urea are changed together into uric acid. If we adopt this hypothesis, it will be evident that under the above treatment this uric acid may be oxidized back into urea and carbonic acid, and the balance of health restored. Thus:

which may thus be proved:

Such may be the action of Nitro-hydrochloric acid. It exerts a true Catalytic or counteractive influence. But we have to explain the agency of another class of very different, and apparently opposite remedies. Alkalies are employed with benefit both in Rheumatism and in Gout; particularly in the former disease. Now I conceive these to act, in Rheumatism at least, simply on the Restorative principle; supposing lactic acid to exist in excess in Rheumatic blood. This by itself may have no more tendency to oxidize into carbonic acid, than so much vegetable acid would have. In ordinary cases a free vegetable acid passes out into the urine without undergoing any change in the system. But it has been proved by Wöhler that the same vegetable acid becomes oxidized when given in combination with an alkali. So that if we introduce into Rheumatic blood a free alkali, a lactate of potash or of soda will be formed; this may then be enabled to oxidize into a carbonate, and the natural process be completed. Such appears to be the rationale of the action of alkalies. They would be inefficacious in Oxaluria, because the oxalic acid has so great an affinity for lime, that it could not be separated from this combination by an alkali.

Dr. Rees and others have found Lemon juice of great use in the treatment of acute Rheumatism. It contains Citric acid, and some Citrate of Potash; the latter being in too small amount to explain the action of the remedy. I have already shown how it seems possible that the vegetable acids may act as refrigerants in simple fever; how they may then supply the place of the natural lactic acid in the blood, and become oxidized instead of the Proteinaceous compounds. (Vide Acids.) But Rheumatic fever is a very different case, for there is here apparently an excess of lactic acid, and an arrest of its oxidation. In considering, however, the formula for Citric acid, we perceive that not only does it contain proportionally more Oxygen than Proteins, as was proved in the former instance, but more than lactic acid contains. It is

Thus it is possible that it may act as a carrier of oxygen to the lactic acid, and so help it on towards its transformation into carbonic acid. It appears to be decomposed in the system, for Dr. Rees has never known it in these cases to increase the acidity of the urine. The matter is obscure; but we can discern enough of it to convince us of the possibility of different medicines acting in diverse ways so as to produce very similar results.

Colchicum has apparently some power in the diversion or control of these morbid processes, which we can only indicate, but cannot further comprehend. It is generally best to give it so that it shall neither produce purging, nor any great degree of general depression.

Mercury and other medicines which promote the secretion of the liver, are found to be of considerable use in the treatment of all of these diseases, but more especially in Gout. They seem to act by virtue of their power in eliminating and producing Bile. And it is likely that some constituent of Bile, reabsorbed into the blood, is able to exert a beneficial influence on the conduct of such processes as those which we have just now considered.

Quinine and Tonics have been strongly recommended by Dr. Todd in Gout; and they seem to be signally efficacious, both in this and in the other Arthritic disorders. This is a very interesting fact. If there should be any truth in an idea which I have explained at length in the article on Tonics (vide p. 142,) it would seem that these Tonics may be of use by supplying in the blood the place of one of the wanting elements of Bile. For in all Arthritic disorders there is more or less of hepatic derangement.

There seem then to be six separate and distinct explanations of the cure of these Arthritic diseases. There are six different modes of operation by which the same beneficial result may follow the employment of Nitro-hydrochloric acid, free Alkalies, Lemon juice, Colchicum, Mercury and Quinine.

So that if it should be proved, which is not unlikely, that the chemical theory propounded above for the purpose of accounting for the production of these disorders in the blood is a correct view of the case, then this explanation of the action of the various remedies used in such diseases would acquire an additional probability. But at present the idea is purely hypothetical, because depending upon a number of things which, although they seem likely, are far from being proved as yet.

All that we can affirm with any degree of certainty is that a number of blood-medicines are applied with advantage to the treatment of these kindred disorders, tending to counteract the morbid conditions by which they are severally produced. These Antiarthritics must operate, then, on the Catalytic principle.

A number of varieties and masked forms of these disorders are grouped together under the general title of Dyspepsia. The depraved condition of the blood which tends to the production of arthritic symptoms may, when controlled and disturbed by various causes, simply manifest itself by causing acidity of the stomach, flatulence, impairment of digestive power, and general lassitude. Different Antiarthritic remedies are applicable in different cases. Colchicum or Nitro-hydrochloric acid are serviceable when this condition of the system is of long standing. Small doses of Mercury are often efficacious. Tonics, and a Purgative occasionally, may be recommended in milder forms of the disorder.

Ord. V. Antiscorbutics.

These are remedies which are useful in the counteraction of Scurvy and Purpura. In these disorders there is a thin and poor condition of the blood, together with a deficiency in the amount of albumen, fibrine, and the solids generally; a tendency to hæmorrhages and ulcerations, consequent on this condition of the blood; and great general depression and debility.

There is no doubt that these changes in the blood are due to a certain morbid action. It seems that there are some kinds of food which are able to prevent the occurrence of this morbid action, or to control it when it has been set up. The worst forms of Scurvy occur among sailors in long voyages, who have been deprived for some time of fresh vegetable food; and it is often observed that those who have been thus afflicted on land have been subjected to the same deprivation.

But it does not follow as a matter of course that those who are thus deprived become invariably the victims of Scurvy. It seems that there are certain constitutions which are more disposed to it than others; and that when these systems are deprived of some articles of diet which are able to prevent or to neutralize the working of the poison in them, the latent morbid action is allowed to commence.

Of all the substances of which trial has been made, Lemon or Lime juice, and Potatoes, are said to be of the greatest use in the treatment of scurvy. The former is generally employed on board ships. These both contain Citric acid and salts of potash. But the chief agent in the cure should be something which is not contained in the food eaten by those who are commonly attacked with Scurvy. The food of the sailors who are thus afflicted consists mainly of salted beef and sea-biscuit. Both contain salts of Potash; neither contain Citric acid. So that from this consideration it would seem as if the free acid must be the remedial agent. Vegetables in their fresh state generally contain a small quantity of this or some other acid; and fresh vegetable food is always the best prophylactic against Scurvy and Purpuric diseases. Various wild herbs, some of which contain Oxalic instead of Citric acid, are used among the poor for this purpose.[41]

Dr. A. B. Garrod is of opinion that Scurvy is attributable to a deficiency in the system of the natural amount of the salts of Potash; he therefore treats it with salts of Potash, and apparently with success. (Monthly Journal of Medicine, January, 1848.)

The salts of Potash, if used on such grounds, would obviously act as Restorative agents, and supply to the blood a material in which it is deficient. But Citric acid could not remain in the blood; and if it cures Scurvy, it must act on the Catalytic principle. It could not supply to the system any permanent material.

Dr. Garrod concludes from analysis that the antiscorbutic articles of diet are distinguished by containing an abundance of the salts of Potash, but that the reverse is the case with the materials which form the staple food of those who are most liable to Scurvy.

He gives the following as the amounts of potash obtained from one ounce of each of the articles of diet named:—

Wheaten bread.259 grains.

Oatmeal.054 "

Salted beef.572 "

Boiled potatoes.529 "

Lemon-juice.846 "

Thus it appears that lemon-juice and potatoes contain more Potash than wheaten bread, and much more than oatmeal. But they do not so much excel salt beef in this particular, and that is one of the chief articles of diet among sailors. And if this deficiency of Potash were the sole cause of Scurvy, then it should be unknown in Ireland, where quantities of Potatoes are eaten, and very common in Scotland, where Oatmeal forms so important an article of diet among the peasantry. I am certainly not aware that such is the case, but believe it is rather the reverse.

In spite of the very able arguments and the instances adduced on the other side, it seems to me that the probability is still in favour of the vegetable acid being the active or curative agent in these antiscorbutic vegetables. It seems to exert a purifying power over the blood in this disorder, of the exact nature of which we are not aware. It is probably not only Citric acid that is efficacious, for it appears that some other vegetable acids, and vegetables which do not contain Citric acid at all, may be used with advantage in Scorbutic diseases.

Ord. VI. Antiperiodics.

Certain mineral medicines of the Catalytic division are employed in the treatment of periodic disorders.

Arsenic is a medicine of considerable power, which, when given in too large a dose, or indeed when given at all in most cases, becomes a poison. It has already been shown to act in the blood, and to produce in it a number of effects of a particular kind. One part of this operation is that it is capable of antagonizing the poisons of intermittent disorders, as also of certain convulsive affections and skin-diseases. In health a poison, in disease it proves a remedy. But the dangerous nature of its action is such as to demand considerable care in the administration of the preparations of Arsenious acid.

Dr. A. T. Thomson states that the action of Arsenic is liable to exacerbations and remissions, and sometimes even intermissions. Thus we may suppose that there is a certain degree of analogy between its operation and that of the malarious poison, by virtue of which it may perhaps exert a corrective power over the working of the latter in the blood. (Vide page 166.) Such an analogy could only exist in the case of a Catalytic medicine. It is not observed of Quina, which is employed in intermittents on the Restorative plan. Arsenic is foreign to the blood, and is in every way a Catalytic medicine.

In large doses Arsenical preparations act on the stomach as irritant poisons. Some of them have been used externally as Caustics, especially in Lupus. But this is a kind of action that does not concern us now.

The officinal solution of Arsenite of Potash was introduced into notice by Dr. Fowler, and is the chief preparation of Arsenic employed. De Valangin's solution contains a Terchloride of Arsenic, and is of less than half the strength of the others. Both of them are used in Ague. Some recommend, in all cases where Arsenic is used, to begin with small doses, as two drops of Fowler's solution three times a day, and gradually to increase the quantity; from the idea that the system will thus be enabled to tolerate the remedy better, and that irritation of the stomach will be avoided. Mr. Hunt deprecates this practice, and recommends regular doses of three to five drops or more. It may be safely continued during the paroxysm of Ague, which is a plan that is generally considered to be unadvisable in the case of Quina. The latter may be given in a very full dose between the paroxysms; but this cannot be done with Arsenic, for the consequences would be dangerous. It is best in all cases to give the Arsenic after a meal, on a full stomach, as then it is less likely to irritate, not coming directly in contact with the coats of the stomach, and being diluted by the food during its absorption.

Arsenic is useful in other intermittent disorders besides Ague, as in the various kinds of intermittent neuralgia. It has been given in some varieties of intermittent pulse, which are not due to organic disease of the heart. Dr. Darwin cured a case in which the beats of the heart intermitted regularly once in every three or four times, by the administration of four drops of a saturated solution of Arsenious acid three times a day.

The preparations of Arsenic have even been used in some cases of Gastrodynia with considerable advantage. In these instances the disorder of the stomach generally assumes an intermittent form. It has been supposed by some that Arsenic in such disorders acts directly upon the nerves; but it appears to counteract all the manifestations of this intermittent poison, whether local or general, by the same action in the blood. (Vide page 212.)

Several attempts have been made at different times to discover a substitute for Arsenic, and a cheaper remedy than Quinine, for the treatment of Ague. Iron is employed with advantage in old chronic cases attended with Anæmia; but it is not of service by counteracting the intermittent, but by remedying the anæmic condition which co-exists with it.

M. Piorry, in the course of some experiments made at the Hôpital de la Pitié at Paris, has found common salt in half-ounce doses to be very efficient. In his opinion it is more efficacious than Arsenic, and second only to Quinine, in the cure of this disorder. The suggestion is a valuable one; but the dose is very bulky, and it would be difficult to prevent it from causing vomiting in many cases.

Alum is another medicine which has been recommended in Ague. It also appears to act on the Catalytic plan; but it has not been often employed.

The compounds of Arsenic are found to exert a curious antiseptic influence on dead animal tissues. They particularly prevent decomposition in animal membranes, by virtue of a combination which Arsenic forms with Gelatine. Liebig has founded on these facts a theory of the medicinal action of Arsenic. (Anim. Chem., part i. p. 206.) He supposes that substances as Arsenic and Mercury may be able to arrest contagious and other disorders in the system in the same way that they control putrefaction out of the body. The use of Salt and Alum in Ague might seem at first sight to countenance such a hypothesis as applicable to the treatment of this disease. But we know that Arsenic does not stop all fermentations. The grain of wheat will germinate, and its starch be converted into sugar, after it has been steeped in a solution of Arsenic to protect it from vermin. And Gelatine, for which Arsenic has an affinity, has not been proved to exist in healthy blood.

The compounds of Mercury, the operation of which in Syphilis is sought to be explained on these grounds, are not nearly so antiseptic as many other minerals. If this theory were correct, then all Catalytic medicines, and all antiseptic substances, should be of equal efficacy in all morbid processes. But this is far from being the case. Many substances which are distinguished for their antiseptic powers are found to have no influence whatever on the progress of these disorders. Are Acetic acid and Creosote of any use in Ague? Does Alcohol prevent the drunkard from contracting Syphilis? And if Arsenic, Alum, and common salt, acted solely by arresting fermentation, how is it that they have no control over the supposed fermentations of Syphilis and other diseases? The explanation required must needs be more specific and particular.

Ord. VII. Anticonvulsives.

I have already sought to show that the metallic substances which are used in the treatment of spasmodic disorders act in the blood, and tend to establish in it a set of actions of a peculiar kind. I am able to add little respecting the rationale of their action to that which I have said of the operation of Catalytic medicines in general. It is certainly very mysterious; and it is perhaps mainly on this account that some have been induced altogether to deny it. But a denial so grounded is disingenuous and wrong, for we must often be content to know and to receive many things that we do not understand.

Perhaps the most evident and characteristic of these agencies is that of Nitrate of Silver in the cure of Epilepsy. The Acetate of Lead, and the Ammonio-sulphate of Copper, have been used with advantage in the same disorder. Dr. Babington strongly recommends the Sulphate of Zinc, given at first in small doses, and then gradually increased, so that it may not produce vomiting.

In the treatment of Chorea, Arsenic is highly esteemed and recommended by Dr. Pereira.

In Hysteria these medicines are all probably more or less applicable; but on account of the obstinate and multiform nature of this disease, their use in it is less obvious than in Epilepsy and Chorea. Hysteria, too, is more under the influence of Nerve-medicines than are the other two diseases.

The great objection to Silver, in whatever form given, is that its salts are liable to be reduced in the system, and it thus tends to produce a permanent discoloration of the skin, either browning it or communicating to it a dull leaden hue. This naturally constitutes a strong ground of objection with the unfortunate patient, who would often prefer to be left alone with his fits than to be turned blue for life.

M. Georget supposes that the advocates for the use of Nitrate of Silver in Epilepsy employ it on the principle of counter-irritation, saying that they attempt to cure a diseased brain by cauterizing the stomach. (Physiology of the Nerv. System, vol. ii. p. 401.) But I am not aware that any English therapeutists have adopted this view of its mode of operation. The dose of the Nitrate of Silver, and the state of dilution in which it is given, would certainly prevent it from manifesting any such action. And we should not be warranted in supposing that any of the medicines of this or any other order of Catalytic remedies could act in so direct and so easy a way as that, even if it were thus possible.

Some have supposed that Nitrate of Silver cures Epilepsy by diminishing an irritable condition of the stomach. But it is observed by Dr. Pereira that the existence of this irritability in all cases of Epilepsy is a mere assumption. The solution of this salt exerts, according to its strength, an astringent or caustic action on all mucous surfaces, and thus improves their condition when they are relaxed, inflamed, irritable, or ulcerated. The occasional benefit which follows the administration of the preparations of Silver in Gastrodynia may be referred to an action of this kind. The action of Arsenic in some intermittent varieties of this painful affection has already been mentioned, and is explained in another way. Caustic substances probably act locally in these cases; but Arsenious preparations exert an Antiperiodic influence in the blood generally.

Tetanus is by far the most incurable of these convulsive disorders. Arsenic and other medicines of this order have been recommended in the treatment; but although some cases appear to be partly connected in their first origin with a certain condition of the blood, this disease is very little under the influence of blood medicines, or indeed of any medicines at all.

Ord. VIII. Antisquamics.

Skin diseases are both caused and cured in a variety of ways. Some are produced by external influences. They may be brought on by mere irritation, as certain kinds of Eczema and Herpes, and are then to be treated with soothing unguents or cool lotions. Or they may even be connected with some external organization, of a vegetable or animal kind, as Porrigo and Favus are traceable to a parasitic fungus, and Scabies is accompanied by the development of a species of Acarus. Others are due to some wrong in the digestive process, or to a plethoric condition of the system. Urticaria is an example of the former, Acne of the latter. They may generally be treated most effectually by the exhibition of salines and rhubarb.

A third class of skin diseases are due to the existence in the blood of certain poisons or peculiar morbid conditions. The eruption may constitute one only among many symptoms of the action of this poison, or it may be the chief or only symptom. The former is the case in Syphilis and the Eruptive fevers. It is with the latter kind that we are now concerned.

There are two modes by which we may get rid of the poison that causes the eruption—Elimination and Counteraction. The first may sometimes be effected by the use of Purgatives, Sudorifics, or Diuretics.

But I have classed in this last order of Catalytic blood-medicines some remedies that have proved useful in counteracting the causes of these diseases. The eruptive disorders alluded to are all connected together both in their symptoms and treatment; but because the squamous diseases, Lepra and Psoriasis, are the most characteristically under the influence of these remedies, the latter have been named Antisquamics.

Arsenious acid, as contained in Fowler's solution, a remedy already twice named among Catalytics, is also the most powerful of these Antisquamic agents. Mr. Hunt considers it to be a specific for all skin diseases that are not syphilitic in their origin. Besides Lepra and Psoriasis, it is found useful in Eczema, Impetigo, and Lupus. In the last disorder it has been used both externally and internally, seeming to be in both cases specific in its action. Thus we find in these skin diseases another special antagonism for this extraordinary medicine, which has already been shown to be of considerable efficacy both in periodic and convulsive disorders.

Pitch or Tar is another remedy which seems to be capable of counteracting the scaly disorders. It may be either applied externally, or given internally in doses of 10 to 20 grains. It has been recommended for employment in some of the other skin diseases, but its advantage in them is not so obvious. When it is applied to the skin, some one of its principles is probably absorbed. Pitch, as a remedy for Lepra, is comparatively of recent introduction, but its efficacy has already been very widely acknowledged.

Tincture of Cantharides and Acetate of Potash, both diuretics, have been employed in Lepra to eliminate the materies morbi from the blood into the urine, and have sometimes appeared to succeed in so doing. But in this, as in many other cases, counteraction is both easier and more certain than elimination. The system itself naturally attempts this elimination, and when it finds it impossible, we often gain nothing by urging it.

I need scarcely say that these remedies are applicable only in simple Lepra and Psoriasis, and not in the syphilitic forms of those eruptions, which are treated best by Mercury, or by other medicines of the second order of Catalytics. These Syphilitic eruptions are distinguished by a coppery or a livid-grayish colour, and by the absence of itching.

Sulphur has been used with benefit in Eczema, Impetigo, and Lepra. It may be administered externally in the form of fumigation or ointment, or internally in combination with an alkali or with Iodine. In the case of Eczema and Impetigo, the fumigation and internal administration are preferable, as the ointment is apt to increase the existing irritation. In the cure of Lepra the mineral waters of Harrowgate and other places, containing Sulphuretted Hydrogen gas, have been much recommended. Thus we have in Sulphur a third Antisquamic medicine. It is more or less useful in all non-syphilitic cutaneous disorders. Dr. Burgess has found sulphur ointment and fumigations to be very useful in Psoriasis palmaris. (On Eruptions of the Face, etc., p. 229.)

Though Sulphur seems to act specifically in the treatment of these disorders, there is another disease of a similar kind which it has been supposed to cure by a mere external agency. This is Scabies. Some have fancied that even here it acted specifically, and that this also was a blood-disease. But Scabies has long been attributed to an external cause, an insect, or, more correctly, an arachnid, which, by burrowing in the skin, is thought to produce the vesicular eruption. The Acarus Scabiei, or Itch insect, was discovered in 1179 by Abenzoar, the Arabian. In 1687 Dr. Giovanni Bonomo wrote a full account of it in a letter to Redi of Florence. It is supposed that Sulphur ointments and Sulphur fumigations have a direct external action in causing the death of this Acarus, by the bodily transmission of which from one person to another the contagious nature of the disease is accounted for.

Dr. Billing considers that the confirmation of this discovery has given the death-blow to an idea which will probably last as long as medicine; viz., that certain remedies exert a special influence in the cure of particular diseases. (Principles of Medicine, p. 75.) But we must not deny the existence of special agents, simply because we cannot understand their operation; for it is apparent in too many instances. And from the circumstance that Sulphur has proved beneficial when given internally in Scabies, as well as the fact that this disease has often an idiopathic origin, I am still disposed to doubt the value of the inference which is drawn from the discovery of the Acarus, and inclined to believe that Sulphur may exert an action of a specific kind in this disease as well as in the others.

Some other internal remedies, and many other external applications, have been used in Skin diseases; but these that I have mentioned are the only ones that appear to exert something of a special action in all cases. Arsenic is perhaps the most universal in its application. It often happens that when this remedy entirely fails, the eruption is connected with a constitutional taint of Syphilis. When there is a suspicion of this, such a remedy as Donovan's solution, containing both Arsenic and Mercury, is peculiarly applicable, because capable of acting in a double way. This medicine also contains Iodine; and either this preparation, or the Iodide of Potassium, should be prescribed when the skin disease appears to be connected with a strumous diathesis.

As soon as the course of Arsenic is found to produce swelling of the face, or irritation of the conjunctivæ, symptoms which denote the saturation of the system with the remedy, its administration should be suspended for a while.

We have now concluded the subject of Hæmatic medicines. I have said that this class has been very generally neglected and overlooked by writers on the subject. For this reason, and because there are some ideas respecting their action which I have thought it worth while to work out and to investigate at some length, I have devoted more space to its elaboration than I shall be able to spare for either of the remaining classes, in the consideration of which we are not likely to encounter so many interesting and debateable points.

Prop. VIII.—That a second class of medicines, called Neurotics, act by passing from the blood to the nerves or nerve-centres, which they influence.

1. That of these, some, called Stimulants, act so as to exalt nervous force in general or in particular.

2. That others, called Narcotics, act so as first to exalt nervous force, and then to depress it; and have also a special influence on the intellectual part of the brain.

3. That others again, called Sedatives, act so as to depress nervous force, in general or in particular.

Having investigated at some length the action of Blood-medicines, we now commence the consideration of another class of remedies, which differ very widely from the last in their mode of operation.

The action of Hæmatics is slow, but more or less durable, because it is evidenced in the blood; and a change in the blood produced by this action continues for a longer or a shorter time.

The action of Neurotics, or Nerve-medicines, is rapid; but it is transient, and is soon over. A Neurotic medicine does not cause any change in the blood; and it cannot remain in it, but soon passes out. It acts by contact with nerve, apparently producing no lasting change even in nerve-fibre; and as the cause of the action cannot remain, the effect also soon passes away. Whereas Hæmatics, durable agents in the blood, are used to counteract the causes of inveterate and chronic disorders; these Neurotics, which produce a transitory, but more or less forcible impression on the nervous system, are employed to rouse it when torpid, or to depress it when over-excited. Rarely of use in chronic blood-disorders, they are given mostly in the temporary emergencies of acute diseases. But it is obvious that even a temporary agent may prove of permanent efficacy by remedying a temporary emergency.

It was feasible to attempt some explanation of the actions of medicines in the blood, occasionally more or less analogous to known chemical influences. But the agency of nerve-medicines is of a far more incomprehensible kind. When we consider that little or nothing is known, or can be known, about the ultimate causes of sensation, or motion, or nervous excitement, there is no need for wonder that we find ourselves at a loss to explain the operation of medicines that influence these conditions.

Thus I must chiefly limit my remarks on Neurotics to defining what their action is, finding it impossible to state with certainty how they act. And the field of inquiry being so limited, it follows that there is much less to be said about them than had to be said of Hæmatics.

Nearly all the powerful poisons that act after passage into the blood, belong to this class. Their action in most points of view is such as completely to exceed our means of comprehension.

Sudden death may be produced by it. But there is no apparent cause for this. We find no erosion or perforation of the coats of the stomach or intestines; no mechanical disorganization of the tissues, or chemical change in them; no hæmorrhage, or vascular disease; no rupture of nerve-fibres. Whence, then, could death have arisen? How could the mere presence of a few atoms in the blood,—half a grain, one-twentieth, or even one-fiftieth of a grain—how could this apparently contemptible influence have produced so essential a derangement of the vital functions as to stop them altogether? It is impossible to answer.

The action of such remedies in the sudden causation or alleviation of nervous symptoms, when applied in the cure of disease, is equally wonderful. How are we to account for their different actions on different nerves? How is it that Opium contracts the pupil, and Belladonna dilates it?—that Digitalis affects the heart, and Stramonium the respiration?—that Prussic acid will cause convulsions, and Hyoscyamus delirium? In what way are these various operations brought to pass? It is impossible to answer.

Though it is, I say, quite impossible to frame for any one of these questions a certain or satisfactory reply, on account of the manifest insufficiency of our acquaintance with the details of such actions as these, yet I must now venture to repeat an idea which I have already referred to at the commencement of this Essay (p. 46,) and state my belief in the bare possibility of the operations of Neurotic agents being explicable upon mechanical grounds. It is generally believed among scientific men that each particle of a compound body is made up of a number of indivisible atoms, each of which is inconceivably minute in size. And as these compound bodies have each a peculiar chemical constitution, so must each of their ultimate parts be composed of a peculiar arrangement of simpler atoms, and thus have a certain shape of its own more or less different from the shape of every other compound atom. Both the substance of a nerve, and the active part of a nerve-medicine, consist of a number of definite compound atoms. And it is possible that the atom of a stimulant medicine may be of such a shape as that it shall be unable to coincide with, or to fit into, the series of atoms forming the sensitive surface of the nerve, and thus irritate this when brought into contact with it; and that the compound atoms of a sedative may so arrange with these nerve particles as to fit among and extinguish their salient points, and annihilate their natural sensibility. We learn from the phenomena of the senses that the nerves are very much under the influence of mechanical impulses of all kinds, and particularly minute and inappreciable impulses of this description. Another fact which gives additional credibility to such an idea is, that those Neurotic substances which are chemically alike are in general alike also in their influence on nerve.

The particular way in which nerve-medicines affect different parts of the nervous system might perhaps be explained by supposing minute chemical differences in the composition of the atoms of which those parts are constructed, sufficient to alter their relations to the atoms of certain remedies. If we adopt the Atomic theory, we must perceive that no two chemical bodies can be precisely alike in the shapes of their particles. This various dissimilarity might throw some light upon the many shades of distinction between the operations of Neurotic medicines on different parts. Thus, as a general rule, both Morphia and Atropia are paralyzers of motor nerves. But they do not act alike on the Ciliary nerves by which the motions of the Iris are controlled. We may suppose that there is a certain chemical peculiarity in the particles of these nerves, by which they are enabled to coincide with the atoms of Atropia, and are thus blunted and paralyzed by them; but are, on the contrary, stimulated and excited by the atoms of Morphia, which have the contrary action, because unable, on account of their relative shape, to dove-tail with these atoms.

This idea is, as I have said, purely conjectural and fictitious, and is indeed likely to remain so; for the thing is not by its nature susceptible of proof, nor is it even possible to inquire into it. And I have only thought it worth while to explain it at length because it is desirable that every statement which is made, however improbable and unworthy of credence it may seem, should at least be placed in as clear a light as possible.

The action of a Neurotic is readily distinguished from that of Hæmatic medicines by the fact of its exerting a rapid and well marked influence of some kind on the nervous system. As it is impossible that the medicines contained in this class should remain in the blood, they therefore pass out of the blood through the glands, and in so doing generally act as Eliminatives. This, their secondary action, will be subsequently considered. It is generally of less importance than their action on nerve; with the exception of some which, as volatile oils and resins, exert a very feeble Neurotic action, but are comparatively powerful as Eliminatives. In this case the secondary action becomes the more important of the two.

The most dangerous symptoms of disease are evidenced in the nervous system. Neurotics are employed to control these symptoms as they arise, but Hæmatics are used to combat the cause of the disorder. As to their relative efficacy, there is an advantage and a disadvantage on each side. On the one hand, nerve-medicines are more numerous and more powerful than blood-medicines, and thus in the control of symptoms they are wielded with more immediate certainty than the others in the counteraction of diseases. On the other hand, the symptom that is dreaded is only relieved for a time by the Neurotic remedy, while the morbid condition that caused it continues, and will perhaps cause it again; but when a disorder is remedied by the employment of Hæmatic medicines, it is more or less permanently cured and put an end to.

In the above Proposition I have endeavoured to state as much as we know with certainty of the action of Neurotics. To this certainty I have already ventured to add a surmise, on which no certain reliance can be placed. But even if the theory of the action by atomic shapes should be rejected as improbable, because affording too easy an explanation of a naturally inscrutable operation, it would still seem likely that these medicines may take effect by exerting some minute and imperceptible influence on nerve-fibre, or producing in it some inappreciable disorganization or change, which has the effect of altering the natural performance of its functions. The effect of mechanical concussion or shock, which may produce death by minutely disarranging the particles of the nervous centres, presents an obvious analogy to the sudden and remarkable action of some nerve-poisons.

Having offered these vague suggestions as to the ultimate modus operandi of Neurotics, I will now proceed to divide the Proposition in which their more obvious action has been stated into a number of minor propositions. These apply to the whole class. The three divisions will be afterwards shortly considered separately.

Some space and labour was required in the proof of the minor propositions relating to Hæmatics, for among them were included some things that are not universally acknowledged; but the above account of the action of Neurotics concerns matters that are very generally admitted, and will not occupy us nearly so long in its discussion.

In the first place it is affirmed that Neurotic medicines pass into the blood. In the consideration of Prop. II., it was shown that all of them,—whether vegetable alkaloids, volatile oils, resins, or mineral substances,—were more or less capable of being absorbed. That they do pass into the blood is proved by the fact that many of them have been detected there, as well as found in the secretions into which they must have entered from the blood. Ammonia, Hydrocyanic acid, Antimony, Assafœtida, Turpentine, Alcohol, and Camphor,—all of which are Neurotic agents,—have been chemically detected in the blood by Tiedemann and Gmelin. A still larger number have been discovered in the urine by Wöhler, particularly of volatile oils and odorous principles. The active principles of Opium, Belladonna, Stramonium, and Henbane, have been detected in the same secretion by others.

Thus Neurotics pass into the blood. That they act after this absorption, and not by contact with the mucous surface, was proved in the consideration of Prop. I.

The second minor proposition is borne out even by the names by which the recognised action of these medicines is distinguished. Considered as a class, they have no action on the blood, but their influence is quickly and obviously exerted on the nervous system, or on the vital functions which are universally attributed to that part of the animal frame. Stimulants are so called because they are found by experience to exalt nervous force; Sedatives, because they depress it. Thus Ammonia is given to prevent Syncope, caused by a weakness or failure in power of the nerves of the heart; and Aconite is prescribed to relieve pain caused by an over-excitement of the sensory nerves. Though in these examples Ammonia acts on the centre, and Aconite on the peripheral nerves, yet they are both capable of exalting or of depressing nervous force in general. But neither Stimulants nor Sedatives, as defined by me, exert any marked influence on the intellectual part of the brain. They do not affect the phenomena of mind, or of the four special senses which are immediately associated with it. This influence is confined to the intermediate division of Nerve-medicines, called Narcotics. Their general action is evidenced by a short or long primary stimulation,—and a subsequent depression of nervous force, which is also of variable intensity. At the same time they affect the mind in various ways; exciting it, confusing it or lulling it. Opium and Alcohol are examples of Narcotics. These distinctions are in most cases obvious and well defined.[42]

The third minor proposition repeats the rule of local access, which has already been enforced in treating of the fifth proposition. It was not necessary to maintain this in the case of medicines acting on the blood; but Neurotic agents must be shown to operate locally on the various nervous organs. I have only to repeat the arguments which were urged before. It is proved that the action of nerve-medicines cannot be propagated by nervous connexion, but that passage in the circulation is necessary; that the course of the latter is sufficiently rapid to account even for the action of Hydrocyanic acid; and that, however near a medicine be introduced to a nervous organ, it does not affect it unless it be allowed to reach it. The nerves are not naturally constituted for the conduction of medicinal impressions, but only for the passage of impulses of volition, sensation, or emotion. And this evidently forms a powerful safeguard to the system against the effects of a poison. The assertion is further maintained by the fact that the action of a Neurotic, when applied topically to the part which it tends to influence, is the same as that which is exerted by it on the same part after absorption. And lastly, some nerve-medicines have actually been found after death in the substance of those nerves and centres which had been affected by them during life.

The use of these medicines in the treatment of disease is defined in the fourth minor proposition. They have no influence in the blood. They are not employed in slow or long continuing diseases. Their applications depend on their known physiological tendencies, already stated. Abnormal deviations from the proper functions of the nervous system are rectified by means of the influence which they exert over the nervous organs.

When the powers of life are sinking, the nervous force on which life depends may perhaps be roused by a strong Stimulant, and maintained by its repetition. Sometimes the emergency may be thus postponed, and the danger escaped.

In violent inflammations and fevers, when the action of the heart is so violent, and the nerves that control it so excited, as to place life in peril, we may do good by the administration of a Sedative, such as Antimony or Digitalis, by which the nervous force may be reduced to its proper level.

Narcotics are used in various cases, to cause sleep, or to quiet mental irritability. Both these and Sedatives are employed to alleviate the different kinds of pain.

Neurotics are thus applied to various symptoms, and to many disorders. Their different modes of action will be detailed more at length presently. It must be remembered that all these actions, powerful though they may be, are transitory. The effect produced on the nerve is not a lasting one, and no essential change in the blood is effected by true Neurotics. They are not natural elements of this fluid, but must quickly pass out of it; and they having thus left it, their action also is over. Thus the truth of the fifth minor proposition is plain.

I will now attempt to give a brief but distinct account of the three divisions into which I have divided this class of medicines.

STIMULANTS.

Stimulants are medicines which pass from the blood to the nerves or nerve-centres, and act on them so as to exalt nervous force, in general or in particular. That is, they may extend their operation more or less to the whole nervous system, having a general tendency to communicate nervous energy; or they may confine their action to particular departments of this system, having no manifest influence on other parts. On referring to the arrangement at the commencement of the Essay, it will be seen that Stimulants are subdivided, according to whether their action is thus extended or confined.

The first order includes all the medicines that are commonly understood to be Stimulants. But as the remedies of the second order obviously exalt nervous force, the term applied to the others on that ground could not consistently be withheld from them, although their action is more limited and local in its nature, being confined to a certain part of the body, and to certain nerves. The same remark may be made of the order of Special Sedatives, which will soon have to be considered.

Ord. I. General Stimulants.

(Mineral substances.—Ammonia and its Carbonates. Phosphorus.

Animal substances.—Musk, and Castor.

Vegetables containing volatile oils.—The aromatic Labiatæ, Compositæ, and Umbelliferæ. Cloves and Nutmeg. Cinnamon, Cassia, Sassafras. Rue, Barosma. The Aurantiaceæ. Canella. Valerian. Mustard. Cajeput and Pimenta. Hops. Juniper, Turpentine. Cardamom. Onion.

Vegetables containing acrid principles.—Senega. Horseradish. Serpentary. Cascarilla. Pepper. Contrajerva. Ginger. Capsicum. Mezereon.

Resinous substances.—Guaiacum. Mastich, Olibanum, Myrrh, Elemi. Copaiba. Peru, Tolu. Assafœtida, Ammoniacum, Galbanum. Benzoin, Storax. Pine resin.)

This list of General Stimulants is long, but it might even be further extended. The majority are produced by the vegetable kingdom. The acrid principles to which some owe their power are intermediate in nature between volatile oils and resins. Some of them are volatile, like the former; others fixed, like the latter. Some of the resinous products contain also a volatile oil. The principles of Capsicum and Mezereon are very similar in their chemical nature to the true resins. (Vide page 85.)

These remedies differ very much in power, but their influence is the same in character. They exalt nervous force in general. They seem to act on the whole nervous system; but their most obvious action is to increase the force and frequency of the pulse, and to invigorate the circulation. They are not, for the most part, very powerful medicines; and their action is seldom so violent as to be succeeded by much reaction. They improve digestion for a time, by a stimulation of the sympathetic nerves of the stomach and other viscera. In large doses they are irritants, and may impair the digestive powers, and cause headache. Though possessing no marked stimulant power over the function of mind, like that of the Inebriant Narcotics, yet they certainly exalt the activity of the brain, along with the other nervous forces.

Dr. Pereira classes the majority of Stimulants among Ganglionics, considering that they only act on parts supplied by the sympathetic system of nerves. But this view of their operation appears to me to be too limited; for all of them seem to have a certain action on the brain.

Thus Ammonia is used in Syncope, a state which no doubt depends upon a shock received by the brain. And there are several things which show that it relieves this state more by stimulating the brain than by merely rousing the heart and vascular system. It is found to be most effectual when inhaled through the nose; by which means it could easily pass at once into the cerebral circulation. Dr. Pereira thinks that when administered in the liquid form it can only pass into the blood as a salt, being neutralized by the stomach-acid. In this case it could only act before absorption. But it is probable that it is too diffusible and too rapidly absorbed to be entirely so neutralized; and besides, its operation when inhaled is the same as when ingested, which seems to point to an agency after absorption in the latter case. For when inhaled, it must be absorbed in the free state. And to suppose that it acts by stimulating the nerves of the stomach only, is to receive a thing for which we find no parallel in the action of medicines. (Vide Prop. I.)

Ammonia has been used with advantage in the prevention of Epileptic fits, being given just before their expected occurrence. It could hardly be of use in this disorder unless it affected the brain.

Other General Stimulants manifest this action on the brain to a greater or less degree.

Phosphorus is a Stimulant. In small doses it quickens the pulse. It somewhat heightens the mental activity. It is said also to have an aphrodisiac operation, due to its powers as a cerebral excitor. Volatile oils possess a certain influence over the functions of the brain, as well as those of the organic nerves. Cajeput oil has been used in Hysteria; employed to control various spasmodic movements; and administered in Typhoid fevers and Asiatic Cholera, to communicate nervous power. The fetid gum resins are well known as Antispasmodics. The spasms which these medicines relieve are due to a fault in the nervous polarity, commencing generally in the brain or nerve-centres,—and are more or less subdued by general stimulators of the nervous functions. Copaiba, an oleo-resin, may cause a general febrile condition, accompanied with headache,—when given in large doses.

So obvious is the cerebral power of some volatile oils, that Turpentine, in large doses, has been known to produce inebriation. It is not generally used for its Neurotic powers, but as a Purgative or a Diuretic; or else it might have been classed among Inebriant Narcotics. I have enumerated it above among volatile oils. It may be regarded as transitional between true Stimulants and Narcotics.

Ergot of Rye is another medicine which has a double action. It is used as a Special Stimulant to the Uterus; but it is also a Narcotic to the brain.

Most General Stimulants are without any marked influence on the mind; but stimulate the organic and merely animal function of the brain, and of the Sympathetic nerve throughout the system.

Concluding that General Stimulants have all more or less the power of exalting nervous force in general, we have still to consider some other questions relating to their action.

It is maintained by some that Stimulants have simply the power of calling forth the nervous force which already exists in the system, and that they cannot create any more in addition to this. But if this were the case, then the reaction, or subsequent failure of nervous power, ought to be exactly equivalent to the first temporary increase of that power; assuming this increase to have been simply abstracted from the natural resources. But we do not find it to be so. The reaction from the effect of a Stimulant is always very slight, and often quite imperceptible.

And there seems to be no à priori reason why we should not actually cause nervous force to be generated. We know that a galvanic current, or even a mechanical cause, may induce it to be suddenly and powerfully manifested. I believe that a Stimulant is able actually to produce nervous action; perhaps by an irritative operation upon nerve-fibre. So by continually repeating the dose of a Stimulant, as Ammonia or Brandy, it is possible to maintain the circulation and nervous energy at a certain level, without the occurrence of any reaction for a considerable period.

But we must take care not to confound nervous force with vital force. The former may be very much increased, as in high inflammatory fever, without a corresponding increase of the latter. The advantage of a stimulant is regulated by this rule. When there is a failure in vital energy, no Stimulant will serve to prolong life, for it cannot communicate fresh vital power. But there may be no such failure of vital energy, and yet a sudden or accidental deficiency of nervous force may serve to peril the continuance of health, or even the tenure of life. For a certain degree of this nervous force is necessary both for life and health. When it is diminished, all the functions must suffer; when it fails entirely, the circulation must stop, and death ensues. It is in these cases that a Stimulant medicine is appropriate. It does not do good by communicating vital energy, but by remedying the want of nervous action, by which want the manifestation of the vital energy is subdued. This must always be borne in mind when the applicability of Stimulants is under consideration.

Some writers have complicated the subject by classing as Stimulants all medicines which tend, directly or indirectly, to communicate vital strength; as Tonics, and remedies which counteract morbid depressing causes. This is in direct contradiction to the rule given above. True Stimulants are only of use by counteracting that failure of nervous force which hinders the manifestation of the vital strength which is stored up somewhere in the system. For I have just observed, that to exalt nervous force is not necessarily to exalt vital force, but that any thing which tends to destroy the former must at length repress and extinguish the latter.

The above considerations apply to the action of these Stimulants on the powers of the system generally. But they may act locally. Thus in moderate doses they promote digestion, by acting on the nerves of the stomach and intestinal canal. They increase most of the secretions in passing through the glands in the blood. In both cases they exalt nervous force; but in the latter case their action is of a particular nature, and will be treated of when they are considered under the title of Eliminative medicines.

To impress the system generally, Stimulants are used when there is a failure of nervous force on account of some sudden and acute disorder, without any material undermining of the vital energies. In long chronic cases, where there is real and manifest vital debility, Tonics or blood-medicines are required. But in such a case as Syncope, or stoppage of the heart on account of a sudden nervous shock, Stimulants are particularly appropriate; also in the latter stage of Typhoid fever, or of asthenic Pneumonia, or of Cholera, where the existence of life is endangered by a great loss of nervous power. In spasmodic diseases, as Hysteria, where the health is deteriorated on account of a derangement of the nervous functions, Stimulants may be of use.

Such then appears to be the modus operandi, and such are the chief applications, of the remedies belonging to the order of General Stimulants. Those of the next order exert an action of the same kind, but their field of operation is on a more confined scale.

Ord. II. Special Stimulants.

(Strychnia; Brucia; Toxicodendron; Ergot of Rye; Borax; Rue.)

These are medicines which pass from the blood to the nerves or nerve-centres, and act so as to exalt the energy of particular nerves or sets of nerves. They do not affect the whole nervous system, but they operate on one set of nerves in the same way that General Stimulants operate on all, though usually with greater energy.

The causes of such a localized action are hid in obscurity; but it has already been hinted that they may perhaps be partly accounted for by the differences in chemical or mechanical structure existing between different parts of the nervous system.

Strychnia, the alkaloid and chief active principle of Nux Vomica, acts as a Special Stimulant, chiefly to the spinal cord and the nerves that proceed from it. Its operation is mainly exerted upon the motor branches. Thus in large doses it causes a spasmodic and powerful contraction of the muscles of the trunk, and may even produce death by rendering respiration impossible. Its action is propagated from a motor nerve to a muscle, and is kept up for some time. In small doses it is useful in certain cases of paralysis. Two things are necessary in order that it may act efficiently. The muscles of the part must be whole and sound; for if destroyed by excessive atrophy or fatty degeneration, they cannot be roused by any stimulus. The nerve, too, and the centre from which it originates, must be sound, or else the medicinal impulse cannot be conducted along it. These two conditions can only concur in paralysis from disuse, i.e. when the incapacity to move a limb depends merely upon its having long been in a state of inactivity, but when the lesion of the centre which caused the paralysis has at length sufficiently healed, and the nerve is now in a fit state to conduct a motor impulse.

Strychnia has no operation on the intellectual functions; neither does it act upon the sympathetic nerves of the heart and arteries, so as to quicken the pulse like ordinary stimulants. It exalts sensibility as well as irritability, but not so powerfully. It is a special Stimulant to the motor and sensory nerves throughout the body. Acting upon the spinal cord, it tends thus to exalt reflex action, which is derived from that centre. In small doses it appears to promote digestion, and may perhaps act upon the ganglionic nerves supplied to the stomach.

Brucia, which is the other alkaloid of Nux Vomica,—and the leaves of the Rhus Toxicodendron,—resemble Strychnia in their action, but are less powerful.

Ergot of Rye is a stimulant to the muscular nerves of the Uterus of the female, but to no other nerves in any marked degree. Borax and Rue possess a similar action, but are not so efficient.

When labour is retarded on account of an atony or debility of the Uterine muscle, and when also there is no obstruction or danger which can result from bringing on contraction, Ergot supplies us with a ready and effectual means of doing this. It is also efficacious in cases of uterine hæmorrhage, because the open mouths of the bleeding veins in the wall of the uterus are closed by the contraction which it causes.

When given in an over-dose, Ergot has a dangerous action on the brain, producing at some times narcotism, at other times syncope. But this is not the effect for which it is employed, and is altogether distinct from its operation as a Special Stimulant, which is exerted only upon the ganglionic nerves of the muscular uterus. In small doses it produces no other effect than this.

Like the other medicines of this order, Ergot is not an excitor of the heart and circulation. Its stimulant action is strictly local in its nature.

NARCOTICS.

This, the second division of Neurotic medicines, is in one sense intermediate between the other two divisions, but in another sense different from both of them. Narcotics are defined to be medicines which pass from the blood to the nerves or nerve-centres; which act so as first to exalt nervous force, and then to depress it; and have also a special action on the intellectual part of the brain.

This primary exaltation of nervous force is produced by some to a very considerable extent, but by others very slightly. Of the three orders into which I have divided Narcotics, which are named from their respective actions upon the brain, Inebriants cause most, and Deliriants least, of this primary stimulation. In the second place, Narcotics depress nervous influence. This depression is not in a direct, but in an inverse ratio to the primary stimulation. The less the one, the greater the other. Thus the depression cannot be considered as the mere re-action from the stimulation, as supposed by Dr. Brown, for then there would be a direct relation between the two effects. But we find that the exhilarating action of Alcohol may often be followed by no manifest depression; and that Belladonna, which scarcely stimulates at all, exerts a very sensible depressing influence.

Regarded simply in their action on nervous force generally, the medicines of the first order of Narcotics would approach very nearly to Stimulants, and those of the third order to Sedatives. But Narcotics have all a power which is possessed by neither of the other divisions.

They influence the intellectual functions, i.e. the mind, and the physical ties by which mind is connected with matter. These physical ties are,—the functions of volition and sensation, by which the mind is connected with the body, moving it or feeling it; and the five senses, by which the mind, through the body, is connected with external things. These intellectual properties, the centre of which is the brain, are more or less affected by Narcotic medicines. The first action of the latter is, to exalt these functions, just as they first exalt nervous force in general. The degree of this exaltation varies, as in the former case. Inebriants stimulate the mind to a considerable degree; Soporifics less; and Deliriants possess least of this primary exciting power. But it is in their secondary action on the mind that we find the most characteristic difference between them.

On referring to the arrangement, it will be seen that I have divided Narcotics into the three orders to which I have already referred by name, and which are thus designated in Latin:

These Orders are named from the secondary action of these different Narcotics on the intellectual functions. In the production of inebriation these functions are impaired and deranged; in sleep they are lulled or extinguished for a time; and in delirium they are excited and led astray. The several actions of these orders will be more minutely described presently, and the individual medicines of which they are composed will be shown to agree with the general definition of Narcotics.

Dr. A. Billing considers that Stimulants call forth nervous force, and Sedatives depress it; and that Narcotics do neither the one nor the other, but merely impede its communication. I do not consider this distinction to be quite correct. Narcotics exert in the first place a stimulant, and in the second place a sedative action; but these actions have no relation in degree, for one of them always exceeds the other, as we have just seen. Thus in the whole effect, either the stimulation must exceed the depression, or the depression must be greater than the stimulation. So that in one way or the other the quality of nervous influence must be altered.

The medicines of the first order of Narcotics resemble Stimulants so far as this, that they tend altogether to increase the amount of nervous force. Perhaps Tobacco and Lobelia are exceptions to this. The medicines of the third order, and some of those in the second, tend on the whole to diminish the quantity of nervous force, and are thus akin to Sedatives. A correct understanding of the differences in action which exist between the groups of Neurotic medicines is, I think, very essential to a right application of these remedies in the treatment of disease.

Ord. I. Inebriantia.

(Alcohol; Wine; Ethers; Chloroform; Camphor; Indian Hemp; Tobacco; Lobelia.)

The medicines of this order, taking Alcohol as the type, approach more nearly to Stimulants than any other Narcotics. When given in small doses, their narcotic operation may hardly be perceived. They are then exhilarants; slightly quickening the pulse, and enlivening the mental faculties. When given in large doses, this stimulating action on the heart and mental powers occurs first, and is now more intense; but it is soon succeeded by disturbance and impairment of the intellectual functions. The secondary depression of the heart is comparatively feeble, except in the case of Tobacco and Lobelia, which are exceptional members of this order.

The disturbance of the mind produced by these medicines is not of a partial, but of a general character, extending to all the intellectual functions. It is called Inebriation, or drunkenness, and may exist in various degrees. The mind itself is confused and bewildered; volition is impaired, so that the man staggers in his walk; and the powers of the senses are disordered or lost. This condition, when carried to an excess, results in stupefaction, coma, and death. These are the several degrees of the same action, which is a general impairment of all the intellectual functions.

Alcohol and the Ethers produce the primary exhilaration in the greatest degree; Tobacco and Lobelia, in the least. Though varying in degree, yet, as far as the stage of inebriation, the effects of these medicines are similar in kind.

Stupefaction constitutes the next stage of the action of Alcohol, Camphor, Indian Hemp, Ether, and Chloroform. Camphor and Indian Hemp exert at this period an anodyne influence; to which also, in the case of Indian Hemp, may be added a very curious imitation of Catalepsy. Ether and Chloroform have at this time a peculiar action in extinguishing the sense of Feeling. With this object they are commonly administered by inhalation in painful surgical operations.

The stupefaction produced by the above medicines is not at all prominent in the case of Tobacco and Lobelia inflata. Instead of that they both exert a particular sedative action on the heart and circulation. This is accompanied with nausea, and with great relaxation of the muscular system, like that which is produced by Antimony. It may lead to syncope and death.

Syncope has been known to be suddenly produced in some cases of the inhalation of Ether and Chloroform. These two medicines are also muscular relaxers, like Tobacco.

The cases which demand the employment of these medicines, as also of the other Narcotics and Sedatives, will be considered at the close of the section treating of Neurotics, and again when some of them are separately described in the fourth chapter.

Ord. II. Soporifics.

(Opium. Lactuca. Hops. Nutmegs.)

Opium, which is the chief and only important medicine of this order, may be considered as the type of Narcotics. It causes in the first place a slight quickening of the pulse, and some excitement of the mental faculties. It is named from its peculiar secondary action on the latter. It produces drowsiness and sleep.

We have seen that the term intellectual function must be understood to include not only the mind itself, but also the powers of volition and sensation, by which the mind is connected with the body,—and the five senses, by which it is enabled to appreciate the external world.

Inebriants affect these three in about the same ratio. Ordinarily they impair the mind, and derange the functions with which it is connected; but they do not quite extinguish either volition, sensation, or the special senses. Soporifics differ from this action in two ways. In sleep the mind may remain active; but it is left alone, dreaming, and uncontrolled by physical ties. For the functions of volition and sensation, and the special senses of Sight, Hearing, Smell, and Taste, are entirely suspended in perfect sleep. So that while Inebriants affect similarly both the mind and the natural functions with which it is connected, Soporifics may leave the first untouched, but they entirely subdue the latter. The condition of sleep differs also in another important particular from the state of inebriation,—as well as from delirium, which we shall have presently to consider. Sleep is liable to be suddenly interrupted or suspended by comparatively slight causes, as a physical shock, or a forcible impression upon one of the senses which are held in abeyance and subjection. Neither inebriation nor delirium can be suddenly put an end to in this way.

Such appears to be the distinction between the operations of these two orders of medicines.

Pain prevents sleep, because it enforces sensation. Thus a mere Soporific, if effectual, would prove anodyne, and relieve pain.

But Opium has an important anodyne action, which is independent of its power of producing sleep, for it may occur without the latter. It is by far the best remedy for pain in the whole catalogue of medicines. It also produces relaxation of the muscular system, and is thus a powerful antispasmodic. In excessive dose it produces a marked sedative effect; causing an imperceptible or irregular pulse, and very slow breathing, with contraction of the pupil of the eye. It may kill by apnœa; i.e. by stopping the respiration.

Tobacco resembles Opium in causing contraction of the pupil, and relaxation of muscular fibre. But it is inebriant, and not soporific; and its secondary sedative action on the heart is more powerful than that of Opium. The order of Deliriants dilate the pupil. Inebriants and Deliriants act on the glands as Eliminatives, being mostly diuretic. Opium has a contrary action; it diminishes all the secretions except that of the skin, which it increases in amount. Most particularly it diminishes the secretion of the bowels, causing constipation. At the same time it impairs the appetite and digestive power, producing often nausea, and coating the tongue. It tends also to produce a determination of blood to the head.

Lettuce, from which Lactucarium is prepared, resembles Opium in its action, but is neither so powerful nor so efficient. Nutmeg and Hops have proved Soporifics when given in large doses.

The relief of pain, and the production of sleep, are about the commonest and the most grateful of the offices which fall to the lot of the physician; and in either case Opium, or one of its preparations, may be said to be indispensable. But a certain caution and care must be exercised, even in the administration of this most useful remedy. (Vide Art. Opium, Chap. IV.)

Ord. III. Deliriants.

(Hyoscyamus; Belladonna; Stramonium.)

These medicines are all produced by the natural order Solanaceæ. Of all Narcotics they approach the nearest to Sedatives. Their only stimulating action is to produce at the very first a slight and evanescent febrile condition,—a quick pulse and heat of skin,—which never lasts long, and is sometimes overlooked.

They are not Soporific. Their action is soon manifested by an anodyne operation, and a sedative influence on the heart and circulation. For this double action they are employed in medicine, being used in painful disorders, fevers, and inflammations. As anodynes they are not so efficacious as Opium, but their action is not followed by constipation, or by a diminution in any of the secretions.

They all dilate the pupil of the eye. Belladonna produces a peculiar dryness of the throat, and has been known to cause an erythematous eruption. Stramonium appears especially to control the respiratory nerves, and is thus used in Asthma, where there is a spasmodic circular contraction of the smaller bronchial tubes. Lobelia, a medicine of the first order, possesses a somewhat similar power. The action of the remedies of this third order of Narcotics is distinguished by the production of delirium when they are given in large doses.

Let us again assume the threefold division of the mental functions, to which allusion has already been made. Inebriants impair equally the mind, volition, and the five senses. Soporifics extinguish for awhile both volition and the senses, but may leave the mind alone. In delirium these functions are not thus impaired and held in subjection, but they are excited and led astray. The mind is occupied intently upon imaginary fancies; unreal objects and hallucinations are presented to the senses. So that Deliriants, in this peculiar phase of their action, tend to excite the mind and the volition, and to delude or derange the senses.

Speaking generally and rather inaccurately, we might say that the medicines of the first order of Narcotics bewilder and impair the powers of the mind; those of the second order subdue and extinguish them for awhile; and those of the third kind excite and derange them.

Certain peculiar and exceptional effects are produced by some Narcotics when they are administered in repeated doses for a long time together. Taken in this way, Alcohol produces delirium tremens, and great despondency of mind; as also often a chronic inflammation of the liver. The continued smoking of Tobacco is found to exert a tranquilizing influence over the mind. And the continual use of Opium or Indian Hemp, both of which are habitually consumed in large quantities in the East, produces a curious and melancholy series of mental hallucinations and disorders.

SEDATIVES.

We have now to consider the third and last division of Neurotic medicines. Sedatives are medicines which directly depress nervous force. Some affect nervous force in general; others confine their action to particular nerves. They are mostly energetic and dangerous agents. For the time being they may destroy nervous power, and remove nervous control.

It might already have been concluded, from what has been said of the secondary action of Narcotics, that there are two ways in which a Sedative action on nerve may be manifested. Sedatives may destroy nervous influence; or they may simply derange it.

Let us suppose a special Sedative to derange the action of the Vagus nerve. It would probably cause the rhythmical contraction of the heart to be abnormally slow or irregular. It would be likely to diminish in the lungs the sensation of want of breath, and thus decrease the number of the respirations; and at the same time it would repress the irritability of the pulmonary mucous surface. Further, it would in some way derange the normal function of the stomach. All these things a Sedative to the Vagus nerve does actually effect. Given in large quantity, it may cause death, by destroying those functions which in a small dose it deranges.

All the varieties in action of Sedative medicines may be accounted for by considering that they may either derange or destroy the nervous forces. In the case of each set of nerves in the body we may distinguish an action of derangement, and an action of destruction, both producible by Sedative medicines. Thus by an action on the motor nerves of the cerebro-spinal system, convulsions or paralysis may be produced. By an influence on the nerves of sensation; pain, or anæsthesia. By an affection of the organic nerves of the heart, or of the brain which controls them; palpitation, or syncope. By an action on the nerves of the lungs; cough, or apnœa. By the exertion of a sedative power over those of the stomach, nausea may result, or vomiting. These various symptoms are all brought about by Sedative medicines, but in each case the first effect is referrible to a derangement, the second to a loss of nervous power. In every instance there is an impairment of natural nervous force.

Narcotics act on the mind. They cause death, with stupor or delirium. Sedatives act on the organic function of the brain, which is necessary to life, but they do not affect the mind. In poisonous doses, they kill by producing syncope, which is a suspension of the action of the heart. Hydrocyanic acid causes at the same time convulsions. These convulsions appear to be caused by a derangement of the nervous polarity of the spinal cord; and not by a stimulation of this centre, as the tonic spasm of Strychnia. (Vide page 232.)

Sedatives are divided into two orders, according to the extent of their action; in the same way as Stimulants have been divided.

General Sedatives have a direct action upon all the nerves and nerve-centres in the body, the result of which is a diminution of nervous force.

Special Sedatives exert the same depressing action upon particular nerves only. Like the order of Special Stimulants, they are peculiar and exceptional agents. All those with which we are acquainted appear to direct their action to the branches of the Vagus nerve.