force which, in this method of manifestation, we call nervous force.

If an animal be deprived of every kind of food except fats, it finally dies of inanition, though there is no apparent emaciation. The changes incident and necessary to nutrition cannot be carried on in the absence of necessary elements. The molecular changes of the digestive process having partially ceased, there is a consequent diminution in the evolution of nervous force, which finally results in complete functional stasis, or death.

Again, that nervous force is identical with the other forces is manifest from the fact that in many of its phenomena it is the same. As light and heat are modified by other forces as well as by the circumstances under which they are made manifest, so nervous force is dominated by the environments which surround its elimination and exhibition. The methods in which the changes which result in light and heat progress, the elements taking part in such changes, all have an influence upon the characteristics of the force so generated. This is also true of nervous force. When the molecular changes going on within the body in which is generated nervous force are most active, the force generated is greatest. When these changes cease, nervous force is no longer generated and the body is dead. When the products of these changes are for any reason transformed into heat, as in certain pathological conditions like fevers and inflammations, nervous force is decreased. If the body be subjected to intense cold, the transformation of these changes into force is retarded, and not only is the temperature of the body reduced, but nervous force is diminished, and the organs which are controlled and regulated by it become torpid. Certain drugs have the power entirely to suspend these transferences of force, or to modify them greatly. So in the generation of other forces through the chemical or other changes which induce them, the elimination or action may be modified or suspended by the introduction of interfering matter.

Nervous force may be changed into other forces, and on the other hand, light, heat, and electricity may be transformed into nervous force. It is not sufficient that the tadpole be furnished with the necessary food and heat for its development into a frog. Unless light be given him he remains in his tadpole state. If heat be not applied to the freezing animal there will be no nervous force; and how familiar is every physician with the fact that when nervous force seems exhausted, the mere application of heat supplies the

needed nervous impulse-how else than by a transference of the force? If I apply the poles of a powerful battery to the nerves of an animal in which the evolution of nervous force is quite suspended, all the effects of that force are manifested. The heart can be made to beat, and any special muscle to act as in life, for a limited time— how else than by the transference of this mode of manifestation of the unit force? Electricity seems more nearly correlated to nervous force than is any other mode of motion. Indeed, in some animals they seem interchangeable at will. Thus the gymnotus, or electrical eel, by the possession of a more than usually complicated nervous apparatus, can give electrical shocks of considerable power at volition.

The fire-flies and glow-worms are also provided with special organs, by means of which they can emit light at will, as the gymnotus does electricity; that is, nervous force is transmuted into light. In all such animals when nervous force is exhausted, when they are tired out by continued irritation or excitement, this power to emit light or electricity is gone, and it only returns when the nervous impulse is again perfect.

The laws which govern the manifestation of nerve-force are less understood than those dominating the other forces. The force itself seems like an algebraic expression to be raised to a higher power, but that it therefore differs from the others does not follow. When in the light of the theory of the correlation of forces it is intelligently studied, we may hope that its phenomena will be better understood, and its conservation become a wrought-out problem. We have learned how electricity may be stored up,-imprisoned against a time of need. Why should we not discover the same thing concerning its nearly-related nervous force? When the battery ceases to work we know how, within certain limits, to remedy the defect. What hinders our learning the same thing of the nervous system? Many men have striven to gain this knowledge, but not, so far as I know, in the light of the latest revelations of science. Nervous force has been regarded, as electricity once was, as an entity, an entirety, as something distinct from other forces. It is time that men began its investigation from another stand-point.

In the first pages of this hastily-written paper I said that the progression of force is, so far as we now know, by undulations and onward, wave-like motions. This is demonstrated by experiment to be true of nervous force. Even the rate of this advance has been determinately measured, and found to be in the motor nerves about

110, and in the sensory nerves about 140 feet per second; so that we see in its mode of progression it obeys the law governing other forces.

Of the manner in which nerve-force is eliminated we know little, but that it is in some way through the nervous centres we are convinced. Experiment has proved this, and at the same time established the fact of its close correlation with the other forces. When the nerve-centres are destroyed or paralyzed, not only is the production of nerve-force stopped, but the body quickly cools. Upon sending a current of electricity along the course of the nerves, the bodily heat or temperature rises, so closely are these forces connected. If an organic body be deprived of light, not only is nervous force diminished, but the temperature is lowered.

We have all known persons whose hair during conditions of nervous excitement would stand on end, and from whom at such times could be drawn distinct electric shocks. I know a man who, by inducing a restless, agitated, nervous state, in favorable atmospheric conditions, can light a gas-jet by simply holding his finger-tips to the burner. These states are always succeeded by nervous depression, undoubtedly due to a loss of nervous power, through its transmutation into electrical force.

That nervous force is very closely correlated with electrical force is again proved by the fact that all persons of highly-wrought nervous organization suffer extremely during electrical disturbances. So-called magnetic storms induce a condition of great nervous exaltation in many people. Nervously anæmic people derive strength from a gentle electric current, because of its conversion into nervous power. People who suffer from nervous irritability find an exacerbation in electricity. That is, when the lesion is of the nerve-centres, the generators of nerve-force,-electricity is beneficial; when in the conducting nerve-filaments, it is aggravative, for obvious reasons.

There are many other points and arguments which I should be glad to present, but this paper is already too long, and I must leave the consideration of the subject. I desired to say something concerning a kind of nervous ebb and flow in certain members of the vegetable kingdom-to speak of the stinging nettles and of certain jelly-fishes, which without a discoverable nervous system yet give distinct shocks through some occult means-to speak further of the inordinate waste of nervous force in certain states of excitement or passionto say something about the anatomy of the nervous system, and to examine a little the phenomena of excessive nervous irritability. I

am even leaving almost untouched one great division of my subject— nervous lesions. I can only plead the vastness of the theme, and the impossibility of doing more than to make a brief presentation of it within the limits of a paper like this.

The importance of a more careful study of the physiology of nervous force is apparent when we remember that the type of American diseases is distinctly nervous, and that from year to year it is growing more so. Reflecting men in the medical profession have begun to recognize that we are making little progress in learning to combat these ills, and they are seriously looking about for the reason. Some of the most profound thinkers in medicine have turned their attention almost exclusively to this field. They have advanced little further than to discover the cause of certain troubles, and lament the inability of the profession to grapple with and overcome the difficulty. Books have been written which have stirred medical men up to a recognition of the importance of this subject, without convincing their authors that they themselves fully comprehended the matter. Is it not time that investigation began from a new stand-point? Is it not time that inquiry took another direction? If any one has studied the subject from the vantage-ground of the correlation of nervous impulse with the other forces, I am not aware of it, but I hope that this may be a door which shall enable some one to enter upon a field that will give richer returns than any have yet yielded.

DISCUSSIONS.

Dr. BUCKINGHAM: I only wish to mention a point or two. When we consider the physical growth of life, we can, to a certain extent, reason. When we get beyond the physical facts and enter the field of speculation, we cannot understand the subject. The machinery may be in perfect order, and yet if you apply electricity to it you cannot make a dead man hear or you cannot make a dead man see. There is something beyond which we do not understand; how far we may travel in that line of knowledge after awhile we cannot say, but there is a border beyond which at present we cannot pass. I do not wish to occupy any of the time, but merely to state that this discussion has not settled the matter. As for the conversion of one motion into another one, or the correlation of forces, I doubt very much if that theory is correct.

SECTION I.

ARTIFICIAL DENTISTRY, METALLURGY, AND CHEMISTRY.

PAPER BY T. L. BUCKINGHAM, CHAIRMAN OF THE SECTION.

F it was the intention when this Association was divided into

I Sections, to have the chairman confine his report to ne

provements, discoveries, or additions made in the branch during the previous year, and were I now to comply with such intention, I should make my report very short, for I do not think any decided improvement has been made, though there has been a gradual advance.

With the introduction of rubber as a base, and of sectional blocks made by the manufacturers, the old process of mounting teeth on metallic plates was in a great measure discontinued. While the new process was, to some extent, an improvement on the old, it prevented the advancement which would have taken place had it not been introduced. It requires much skill and nice workmanship to mount a set of teeth on a metallic plate; and when the teeth have to be carved, burned, and ground to fit, and arranged to give the proper expression to the face, it requires more than ordinary skill to perform the task properly. Teeth are now manufactured in quantities, and all that is required of the dentist is to select such as wil! come nearest to suiting the case. The fitting to the plate is dispensed with; in fact he does not want them to fit closely to the gum, because the rubber will fill the space. All he has to do is to make close joints and finish smoothly. He may vary the color and size for the different cases and make some a little longer or shorter than others, but they all have the same regular form and look as much alike as shoes, hats or other articles of dress that are sold in the stores.

Natural teeth vary in shape, size, color, and arrangement. If you were to examine all the mouths in this city you could not find two exactly alike, and one of our objects in inserting artificial teeth is to imitate nature. It is therefore evident that teeth made in sectional blocks and arranged as they have to be in regular order cannot imitate natural ones.