What demands our first consideration in administering a dose of medicine, aside of its physiological applicability, is an estimate we have to make of its dynamic force. We can do this systematically, in a measure, on a scale from 1 to 100, as represented in the table of Therapeutics in this work. The higher the number the more powerful the remedy, and as the numbers run lower, the milder in force. This estimate of the force of a medicine is more cautionary than arbitrary. Many circumstances may intervene to change its status given in the table, in particular in many forms of sickness, in idio-syncracies, and by a combination with other remedies, etc. But on a general physiological basis the scale is exceedingly convenient, and a safe guide to go by for any consultant in administering a remedy for the first time. In estimating the dynamic force of a prescription we must observe it, independent of its component parts. For example, chloral stands at 80, and iodide of potassium at 60. The combination of the two would give it a place in the scale of deadly poisons. Where carbonate of ammonia, at a force of 55, and iodide of potassium, at 60, are combined, the ammonia will not materially lessen its force, but the iodide will be changed, even to the extent of destroying all tendency to iodism. Suppose we administer opium at 85, in connection with iodide of potassium at 60. Both would be somewhat augmented in force. Here opium stands with equal force with chloral, but not in combination with other medicines, but as two independent agents. Let us take chloral in connection with strychnine at 96. As these are antagonistic in their physiological effects, in combi-nination they both greatly lose force. The same is the case with belladonna and opium, and many other remedies. Corrosive sublimate and opium united are mutually augmented in force, and so are arsenic and tobacco.

The question naturally arises, where is the pharmaco-dynamic action of a medicine centred? Let us take quinine, at 70, to solve this question. Quinine, in small quantities, stands preeminent as a tonic or stimulant, and it is also just as true that in large doses it outranks every other article of the materia medica in reducing exalted temperature of the body. Now, there are, in some respects, two opposite, or, at least, altogether different pathological conditions, for the alleviation of which it is administered, in the former case to revive falling activity, and in the latter to depress activity.* According to our formula, the given force is manifested in the administration of the remedy tending to cinchonism. Few, if any, therapeutic agents are characterized by but a single mode of action, but produce effects in keeping with the quantity, administered or applied, and the condition of the body at such a time,* neither is the elementary composition of drugs sufficient to explain the properties of medicaments and their diversity of action. Perhaps the relative molecular structure alone, between the medicine administered and its organ of selection in the animal body is the source of its force in whatever degree it may be manifested. This theory would explain why some drugs are highly poisonous to some animal life, and to that of others perfectly harmless.

*Dr. Thomas J. Mays.

The legitimate force of a remedy cannot be produced without the aid of a physiological force to meet it. It is impossible to induce emesis in subjects who are in an adynamic state, †and in a state of profound collapse, the stomach will accept nothing for assimilation and absorption.

The effects of remedial agents are more intense when the economy is already turned in the direction towards which the medicaments tend to impel it, the effects, on the contrary, are less inlense, or what amounts to the same, tolerance is greatest when the economy is turned in the direction opposed to that towanls which the remedial agent has a tendency to impel it. †

It is important to seek an explanation of the circumstances which cause variation in the physiological and remedial effects. There are two principal causes for the variations of action; the first is the power of the agent itself, which varies in different cases and under different circumstances; the second is the ensemble of phenomena as regards the organism. †

The peculiar power of a remedial agent is not an expression having always the same significance; it does not signify that a medicament is always endowed with the same virtues, and in the same degree, and that it can always exercise a calming or stimulating action. The peculiar properties possessed by the remedial agent are not thus in relation with the particular conditions of pharmaco-dynamic energy possessed by or inherent in it. †

The physiological vital force necessary to manifest the dynamic action of a drug, whether molecular or chemical, or both, in combination are but depending operations in that simple chemical process of the action of oxygen carbon and hydrogen, which is so intense in its effects that nearly all the force which is generated outside and inside of the body results from its chemical combination.

In admitting a scale giving the power of a remedy, it is likewise admissible to make an estimate on the constitutional condition of the patient: let 1 stand for general good health and 100 for death, the intervening numerals giving the different degrees of constitutional impairment. We will show the importance of both of these scales - the one physiological and the other pathological - in another part of the book.

Chemical Changes of Medicine in the Stomach.

There are few remedies that are not materially changed when introduced into the stomach. Therefore it is of frequent occurrence that medicines are not admitted into the system as represented in a prescription. One ingredient ma}-modify the other, as opium and acetate of lead. They act chemically on each other in the stomach, producing the acetate of morphic