You may show the track of the buffalo to the hunter, and it may be never so fresh and capable of being followed by the instinct of the dog or the sharp eye of the animal that is after the buffalo, but the tracks themselves would make a poor dinner. Just such dinners have we been invited to by those who claim that the germ theory -and they use the word theory in the sense of speculation only— by those who claim that the germ theory is demonstrated to the exclusion of physiological processes. I commend the last speaker with my heartiest congratulations, and I wish to express to the author of the paper which has been read my deepest affection and mental recognition of the clear delineation of his comprehension of the subject before us, as presented by him. What is a process? It is a going on of something to something. What is a thing? It is a mental concept formulated. It is a think formulated and defined; a distinctly perceived thought. I thank you for saying that pathology is only perverted physiology. The function of building a tooth is the evolution of all its parts. The function of decay of the tooth is a perversion of the currents of energy. Therefore, decay is the reversing of a current. What is that current which we nominate a nutrient current but an evolutionary current—a building-up of the elements that constitute the tissues that we are dealing with? And we are now dealing specifically with enamel and dentine. The action of these currents is in obedience to what I have been much abused for calling a typal order. The typal order of the enamel is a modified typal order of the dentine. The influence of the lime-salts is similar, and we see a harmony in the protoplasmic lines, showing that it is really a living tissue that has to be nourished to be kept in proper condition. It is that nourishment that we are talking about. I have just said that decay was a perversity of a nutrient current, of a nutrient activity. What are lines of nutrient activity? They are courses through which the blessed light of heaven, plus energy, go to organize teeth and other parts of this wonderful system of ours, which we dissect so as to get at their anatomy.

My friend persisted in saying "decalcification," when I asked him about it. He did not mean that at all. God bless you, my friend, for saying there was no appreciable difference in the amount of limesalts of the tissue taken from the dominion of decay, that it was exactly like healthy tissue in that the equivalents were there in their exactness.

What is it which takes place when a fellow comes into your house

to court your wife and take you away from her, or her from you? He has no effect at all until he can pervert her currents of affection; and then good-bye to peace in that house. That is exactly what goes on in the components of the tooth. You don't see the point, but I will tell you in a minute. When the combination between the husband and the wife is taken away, then you can get a divorce much more easily. What is the corresponding combination here in the tooth that we are talking about? The stiffness is caused by the hardness of the lime-salts in the relation that we call the basissubstance of the dentine. Are there any bacteria there? Who of us have seen any bacteria there? Observers have never seen any in the intermediate basal substance, which is nothing but lime caught. in the meshes of the glue; that is the enamel basis. We find the attacks on the structure of the tooth taking place in this basal substance; softening of the tubules going up the fibrillæ. And yet you find no bacteria there.

I do not pretend to say what the process is that is now being revealed to us, or near the revelation of which we are, as to the proliferation of these so-called micro-organisms; but I have this to say, from the depths of my affection, from the best action of brain and my profoundest conciousness, that they are not seen by us by the highest power of amplification and concentration of light that we have yet had. The ghost of the bacterium is the first thing, before the bacterium can take conformation; or else you could not differentiate that. When we can catch the ghosts and get the form and specificity of the ghosts, we can reach the beginnings; but when we can only take those after they have been ripened by reason of the presence of the ghostly inhabitants we shall be dealing only with the tracks of the game, and we shall not have a very satisfactory dinner. That is the kind of a feast we have been having for years. Let us hold fast to the truth as we have it, and strive for more light and more proof. We want, in our own mental ratiocination, to get at the demonstration of truth and reveal it to all the world. When we have an object under the microscope, let us carefully note all that it reveals, whether it sustains our preconceived view or not. Let us not be led astray by any argument that because some one else has not seen something, therefore it cannot be seen. As has been said with regard to these nutrient currents, they are so fine and so spirituelle that the natural mind, the ordinary percep tion, cannot see them, until it is converted. Now, in our mental processes we have just to return to the embryonic condition; we

have to assume that we are novitiates before we can progress. I would rather take five boys, fifteen years of age, who had simply an English education, and agree to make them good anatomists, physiologists and pathologists, therapeutists and operators, in the succeeding five years, than to take five graduates and agree to make them first class men in the same time. Do you know why? Simply because there would not be so much error to combat.

Let us encourage the men who are making these investigations, until they shall bring all out so clearly that he who runs may read. Dr. SPALDING: I have long held the opinion that there is no pathological science except as it is preceded by physiological science; that there is no pathology, per se. There are no such things as pathological functions. There are no such things as pathological growths, per se. The processes are all physiological processes inverted or perverted, and the growths are physiological growths out of place. I know that we do not much understand, first, the science of physiology, and second, the science of pathology; hence I arise at this time to set forth these particular views, that we may get a clearer apprehension of what we are studying. The study of physiology should precede that of pathology, for how can we comprehend the condition of disease unless we first know that which constitutes health? In the unfolding of medical science physiological knowledge has ever opened the way to a knowledge of pathology; hence, a cellular physiology rendered the theory of a cellular pathology possible. Our text-books are full of descriptions of pathological anatomy, of pathological growths, and of pathological processes, when, as Dr. Atkinson has well remarked, there are really no such things; but they are simply inversions of true physiological forces, which produce results which are called pathological. I only wished a little more forcibly to bring out the idea which was alluded to by Dr. Atkinson.

Dr. BARRETT: We came here not to study ghosts, but material things. The question that is presented for our consideration is not that of the tracks of the game at all, but the game itself; and we wish to get down to the actuality of it. Concerning the pathology and etiology of dental caries, until within a comparatively short time, we have not arrived at anything definite. It has been demonstrated, within a few years, that micro-organisms play a much more important part in the universe than had been suspected. No one would have dreamed that they could be considered as important factors in dental caries, until within a very short period of

time. Leber and Rottenstein demonstrated the existence of a fungus in the mouth; but we are not speaking of animal bacteria. The fungi of dental caries are of a vegetable nature. They do not exist at the same time as, nor in conjunction with, putrefaction. Milles and Underwood made certain observations in which they undertook to follow the lead of Dr. Miller, and re-performed the experiments upon which he had based certain conclusions. They made this statement, -that they prepared cultures, and kept them under the conditions which he stated until they became so offensive as to preclude the possibility of further observation. They had putrefactive organisms present, and consequently could not produce artificial caries. There was something lacking. They did not obtain the same conditions that Dr. Miller produced, and which he had stated were absolutely essential to the production of artificial caries. I would not detract from the credit that is due Milles and Underwood or any other gentlemen. The American school of observers have dived as deeply into that matter as anyone else.

Dr. Miller has not identified himself with the German school, nor with any other, except the American school; consequently, when we look upon him as a foreigner, or as pursuing German methods, or when gentlemen say that he is following the instructions of the German schools, they could not be further off in their speculations.

The chief point upon which all this discussion rests, so far as Dr. Miller goes, is the fact, as I stated, that caries is produced or accompanied by fermentative organisms. Dr. Miller has performed a great many of these experiments.

Prof. Mayr is a man whom we all honor, and we all appreciate the work that he has done. But where Prof. Mayr has made one analysis of decalcified dentine, Dr. Miller has made fifty. Prof. Mayr has made his analyses with the utmost care. Dr. Miller has done the same. Prof. Mayr has done it in the solitude of his laboratory. Dr. Miller has worked with the co-operation of, and his work has been submitted to, men like Koch, DuBois-Raymond, and others, the first histologists of the world. And some of the results obtained by these gentlemen are directly antagonistic to those obtained by Prof. Mayr, and must be proved or disproved by the corroborating circumstances, or by other observations. It is not for you or for me, who have made none of these observations, to pronounce between the two. It is only for us to say which seems the more reasonable.

[At this point Dr. Atkinson rose and addressed the Chair, for the

purpose of obtaining the floor. Dr. Barrett refused to yield, and continued:]

I desire to present my own stand-point on this matter, and to state my belief in regard to it. Roughly stated, the process is something like this: The organisms in dental caries are fermentative organisms. We have present in the mouth at all times conditions favorable to their growth. We have moisture and sugar. If we have not sugar, we have starch, which is easily transformed into it. The first process, according to Dr. Miller's theory, will be the decalcification of the superficial portion of the enamel. In decay of the enamel itself it is pretty clearly demonstrated that micro-organisms cannot play any important part. But after the decalcification of the enamel comes decalcification of the dentine. The lime-salts are removed, so that it becomes a spongy mass, which takes up the saccharine fluids of the mouth that are favorable to the development of fermentative fungi, which there go through their life's history. In the course of their existence they produce or excrete an acid, of which Dr. Miller has made a careful analysis, and finds it to be lactic acid. The lactic acid which is there formed continues the work of decalcification in advance, leaving the vital, organic portion of the teeth for the further development of the organisms. They in turn excrete or secrete a further production of acid, which continues the process of decalcification, and so the process is extended indefinitely; and this is progressive caries. Dr. Miller's views are founded not upon theorizations, and were derived not from his books, but they were developed through his microscope in his laboratory, and are based upon actual observations, thousands upon thousands of which have been made.

Dr. ABBOTT: Dr. Barrett has said that we are dealing with actualities and not with ghosts. I think I understand what is meant by ghosts in this connection: something which we have not been able as yet to discern, either with the naked eye or with the strongest powers of the microscope. Does this put us in the position to conclude that there is nothing beyond what we can now discern? Is there nothing yet left to be found out, or to be discovered? Is it possible that we are not going to have powers of the microscope that will reveal to us things of which we have to-day no conception at all? How was it forty, thirty, or even twenty years ago? Have we not been every year discovering ghosts? Are we not at this very moment at work investigating and endeavoring to unearth the very ghosts that he is talking about? My friend, large as he may ap