be-'witb&ht ft for &ny consideration; He had gone Bo fat as to give it to the same patient sfct days in succession, without any incon^ venienee or bad effects whatever. Within a Week past I have had one of those superlatively sensitive patients in the chair every other day for ive or six hours at a time, and performed difficult and painMi operations with impunity, and without any unpleasant effects Whatever. There have been no ill effects in any instance. I generally i*ecbmineftd the patient to take some saline Waters the following morning. The compound seems to be a substitute for fbod, a& tobacco oftentimes is; persons taking it have no disposition to eat or drink .during the day, and on arriving at home, instead of eating meats and other solid food, they have an appetite for fruit and vegetable diet,—fruit especially. I have proceeded in my experiments with great care, prudence, and delicacy, and I am satisfied that this article will be a boon to our profession. I want all of you to test it for yourselves, and any hints or assistance I can give you in the matter I shall extend to you with pleasure and satisfaction. My method of introducing it into the system is this: An hour previous to the proposed operation I give one-sixtieth of a grain of atropine, which can be obtained of McKesson & Eobbins, or any other drug manufacturer. It is manufactured in a variety of forms. I give it to my patients in various quantities, according to their peculiarities or idiosyncracies; for we know that some persons can take with impunity sufficient opium to kill a number of persons with no injury to themselves. I start with one-sixtieth of a grain of atropine, combined with one-eighth of a grain of morphine; and an hour afterwards I repeat the dose. When I have ascertained the particular idiosyncracy of the patient, I often increase the dose of morphine. With the lady I had in my chair yesterday I started with onesixtieth of a grain of atropine and one-fourth of a grain of morphine, and an hour afterwards I repeated the dose of morphine. Those two doses carried her through the day. With some one-eighth of a grain Of morphine has the effect that one-half a grain has upon others.

The suspension of the action of the salivary glands by atropine is an effect which is exceedingly interesting. The mouths of some patients under its influence are as dry as possible. Oftentimes I can fill their teeth without any protection whatever against saliva. In no instance have I used a rubber-dam while the patient Was under the influence of atropine. I use a napkin as a matter of precaution, but I often take them away as dry as I put them into the mouth,—I have no trouble whatever. I throw this out as a hint ami suggestion to you, and I think that, if you act upon it, you and the profession at large Will-derive great benefit from it. I presume I have written

'one hundred letters upon tl?te subject since last winter, and my large correspondence with the profession all tends to establish the great practical value of this agent. It can be introduced into tbe system in a variety of ways. You can make a liquid solution of .both atropine and morphine, and introduce them into the system hypodermieally. I have been experimenting with it in different, forms, and always with success. Either method is entirely unobjectionable. In pursuing these experiments I have derived most valuable" aid from the suggestions of Dr. W« J. Morton, of this city.

While I am up I would like to direct the attention, of the members of the profession present to another discovery whieh has been made recently by Dr. Koller, a young German ophthalmist at Heidelberg. At a recent convocation of the Ophthalmological Congress in that city he made an expositipn of his discovery, which very likely will prove a boon to us in our profession. It is a new local anesthetic. We are all familiar with the properties of coca,—the leaves of the erythroxylon coca. Humboldt tells us in his works how the inhabitants of Peru, who make themselves beasts of burden for carrying merchandise up the mountains to the city of Quito, some ten thousand feet above the level of the sea, require only a pocketful of coca leaves for their subsistence, its tonic influences being of such a high order. It has been introduced into materia medica in various forms as a specific in that direction. Heretofore we have known it in the form of leaves, decoctions, or extracts. M. Niemann found in coca a new alkaloid, which he named cocaine, with the formula Cyi^^Og. One kilogramme of coca leaves gives about two grammes of cocaine. This alkaloid is bitter, and produces a very decided numbness of the tongue when brought in contact with this organ. It is yellowish-white, and appears in the shape of soft, silky prisms. It is almost insoluble in water, quite soluble in alcoholized water, and very soluble in alcohol and ether. Cocaine has a very alkaline odor, completely neutralizes acids, and forms with them salts difficult to crystallize. Dr. Koller, in his recent exposition of experiments before the Congress at Heidelberg, made known the fact that a few drops of the muriate of coca, or cocaine, dropped into the eye ten minutes before an operation, rendered the eye perfectly insensible, so that the surgeon could then perform the most critical, delicate, and severe operations upon it without producing any sensation whatever; and if the operation was prolonged it was only necessary to apply a few more drops of this agent to the organ, and the insensibility would be continued until the operation could be completed, afterwards passing away in the course of fifteen or twenty minutes. I derive my information in regard to this new anesthetic from the last number of the Medical Record, in a letter from its special correspondent,. Dr. Noyes, at Kreuznach, Germany, and I would recommend you all to obtain the paper and read it. If it is a fact that we can localize our anesthesia, —if we can induce local anesthetic effect upon the eye and other parts of the system,—I do not see why it may not apply to the teeth and their surrounding tissues, and especially to sensitive dentine; in fact, to all the operations connected with the teeth and mouth. We are very apt, when a discovery is made of importance equal to this, to jump at hasty conclusions, and think we have discovered the philosopher's stone, and that we have found a universal panacea. Your experience will bear out mine when I say that oftentimes we find before we are far advanced in the matter a shadow comes over it, and the utility we fancied we saw is obscured. Nevertheless, this may prove all we hope for in the premises. At all events, I would advise our investigating the matter thoroughly. Cocaine bears the same relation to coca that quinine does to Peruvian bark, or morphine to opium. I do not think it will prove comparatively of greater expense. Dr. Squibbs, of Brooklyn, is already manufacturing it; so are Foucar & Co., of this city, from whom it can be readily obtained. From the sixteenth century to the present time coca has been the subject of learned essays by the most eminent men of the day. Dr. Monardes, of Seville, as early as 1565; Linnaeus, the celebrated naturalist; Humboldt, and others have testified to its remarkable qualities. In Peru, from the earliest times, it has ever been regarded with a sentiment of veneration, and is characterized as the "Divine Plant." Prof. O. Eeviel terminates his article on coca by saying, "Much still remains to complete the physiological and clinical study of coca. It is known that it acts upon the sensory and motor nerves. This substance will some day have an important position in therapeutics.1' In the light of Dr. Roller's discovery, these words seem truly prophetic. Moreno, in 1868, showed that local injections abolished reflex movements for a time, and Von Anrep, in 1880, showed that the sensibility of the skin was abolished when hypodermically injected, and that of the tongue when touched with strong solutions. The same author applied a solution containing one-half a milligrame to the conjunctiva, and found that it caused a temporary dilatation of the pupil, which was increased by adding atropine. Strangely enough, Anrep did not note that the conjuctiva was insensible, or, if so, did not appreciate the practical significance of the fact. It is strange, too, that when M. Niemann found that the alkaloid produced a.decided numbness of the tongue he did not follow up the hint, and anticipate Dr. Koller's discovery by some thirty years. Dr. Perry. I was told by an eminent oculist that everything Dr. Dwindle claims for cocaine is true; that, while the operation was performed without pain, the patient was sensible, and not otherwise under the influence of the drug at all.

President Jarvie. We will now listen to John T. Codman, B.M.D., of Boston, who will read a paper on

Inflamed And Sensitive Teeth.

"First principles are necessarily assumptions; they cannot prove themselves," says Froude. Individual instances may be proven by individual observation, investigation, or experience; but the knowledge and application of a principle will solve the method of a thousand cases that would otherwise demand a thousand separate investigations.

My object in offering this essay is to try to present to you the principle that underlies the condition of inflammation applicable to a class of teeth not ulcerated; not aching from exposure of the dental pulp; not even decayed ofttimes, but still painful and annoying, and1 offering no apparent excuse for their condition,—being teeth classed as aching from obscure causes; as well as the condition applicable to a large number of ulcerated teeth.

Pain is always caused by pressure. This I assume to#be a law or first principle applicable to living human bodies. I hardly feel it my duty to demonstrate this fact, but the observation of many years increases my faith in the correctness of this assumption. In this connection pressure is not only referred to as that occasioned by blows or falls and their immediate results, but pressure due also to the reaction from injuries, shown in the enlargement of the part or parts injured, which is due to the increased flow of the bloodt lymph, and nervous fluids towards the contused spot. Strictly speaking, there is no such thing as an inflamed or sensitive tooth. Only after years of professional life do I realize this fact. It has taken me so long to thoroughly disassociate the idea of pain in a tooth from what is ordinarily called the tooth—that is, from the actual tooth-substance, the bone, i.e., dentine and enamel—that I may say it is only just lately that I have fairly realized it. Yery few of us realize, when we strike the edge of our instruments across the flinty materials that constitute the exterior tooth, causing a spasm of pain to our patients, that these substances have no pain-giving power in them; for, when the members of our profession truly realize it, they will rise to a higher plane of practice, and have clear and unmistakable results, where now they grope in the dark.

Allowing these premises to be as stated, it is reasonable to ask the question, Whence comes pain, and where is its source in a tooth? The answer is, always and every time, from its fleshy constituents, and never from any other source. Try, then, to thoroughly realize that the lime and other mineral products of which the enamel and dentine consist have not a single element of pain-producing power in them; and then let us in our minds divide a tooth into two parts, and we have then, as is the fact, one part, the bone part, nonsensitive ,* the other part, the flesh part, sensitive. Consequently, all the tooth pain must be in the part which is truly flesh and sensitive. In this condition of mind we are ready to approach the subject of inflamed teeth, and will be able to comprehend at once that two conditions exist that may cause sensitiveness—in other words, inflammation—in the fleshy constituents that lie in and around a tooth; these being the only tissues that can be sensitive; the one condition being pathological, connected with the flesh part, and the other mechanical, connected with the mineral part; both occasioned by pressure, but from widely different sources.

I have been for years studying to realize practical results from this theory, keeping always first principles in sight, and getting a clearer vision as I proceeded. Simple as this theory appears, there is in it a wide field of study. It will be found to be a "high science," for it involves within itself conditions produced by malocclusion; results of accidents occasioned by falls, blows, and injuries; inflammation of the periosteum; congestion and ulceration of the same; inflammation of the pulp; strangulation of the pulp, and congestion of the same; dental abscess, etc.

Having disassociated the idea of pain from the bony tissues of the teeth, we can more easily associate the teeth with the mineral kingdom, and can look on a tooth as a block of marble, a piece of stone, or anything truly hard that is placed in the jaw to crush food with.

We have thus two different ways of looking at a tooth, corresponding to the two different substances of which it is made,—the one way as a sensitive and often a very highly sensitive organ, and the other way as an entirely non-sensitive onel Having made these distinctions clear to our minds,—a thing harder to do than at first thought it would seem to be,—we will proceed to consider the causes of sensitive teeth; or, in other words, the over-sensitiveness in the fleshy constituents of the tooth organism and its immediate surroundings. Two principal causes here exist for sensitiveness,— the one physiological, or pathological, if you prefer the latter word, and the other mechanical, or produced by mechanical means or causes; usually induced by the mineral irritant, the hard, unyielding bone of the tooth; non-susceptible to pain in itself, but productive of any amount of pain as a mechanical irritant when in Vol. xxvii.—2.