To perform their proper or normal functions living structures must be excited to activity by stimuli or irritants. Were there no stimuli in operation in the world then tissues, even though they had the capacity of life, would be as inert and inactive as the stones. In fact, we cannot conceive of life continuing or proceeding without at the same time our being conscious of the necessity of stimuli acting upon the things that are endowed with life. There is a French proverb that to live is to react-vivre c'est reagir; that is, that the concept of life is impossible without the concomitant concept of reaction. And reaction of necessity implies the idea of a response to something. A response to what? Why, to stimulation; to irritation.

Tissues have the capacity of multiple and multiform responses to varied forms of stimulation. Tissues are of use, tissues function, only in so far as they initiate and continue activities in response to stimuli. In the absence of the latter they are "dead" as the proverbial door nail. They are the most wondrous and most exquisitely adjusted instruments in the world, but if they are to play their tunes their chords must be touched.

Stimulus initiates and keeps up the periodic process of digestion. Stimulus arouses and continues the necessary function of respiration. Stimulus gives birth to the thought, the dream, the idea. And when tissues are no longer capable of reacting to stimuli it means that from them life has fled.

Broadly speaking, animal structures are so constituted that they will react in a peculiar, and what we may call a characteristic, manner to certain definite stimuli. The stimulus that excites the act of inspiration falls on unresponsive matter if applied to the digestive system, Similarly the application of food to the skin would be entirely without noticeable effect. The normal or proper functions of the various tissues are the activities that are called forth by forces which act in a particular manner on the particular tissue involved, and in a way that serves best the economy of the whole animal body. There is, of course, a maximum and a minimum stimulus or irritation to which a tissue will normally react, just as the tissue possesses a maximum and a minimum capacity of reaction to varied degrees of irritation without thereby undergoing any abnormal alteration of structure. Every animal species has what we may call its upper and lower limits of normal functional response to external forces. So has every organ, every tissue, and

every cell. We may look upon these upper and lower limits as those that bound reactions that do not strain the tissue to the point that they impair its structural integrity, and thereby its subsequent ability to functionate.

Many reactions of the tissues are being brought into play continually throughout life, because they are absolutely necessary to the maintenance of life. It is thus with the reactions of the digestive tract to the introduction of food, by which digestion is accomplished, or with the reaction of the proper center in the brain to the carbon dioxide of the blood, by which the inspiratory act is initiated and every cycle of breathing begun. On the other hand, all tissues and cells have potential or latent capacities of reaction to stimuli or irritants that may only occasionally be brought into play, or, indeed, in certain individuals, may never be aroused. And if we' look into this matter more closely we are likely to find that a very large number, if not most, of these reactions when aroused are of a protective nature in the sense that they bring about structural alterations that can more efficiently resist an environment which might be injurious to normal tissue.

With the coming of Spring the boy takes off his shoes and stockings, and gingerly picks out his path along the highway. At first his every step on rough ground involves some pain or discomfort. But within a few days all this changes. With no inconvenience to himself he now runs and leaps over stones and stubbles and sun-baked sand that a week or two before he would have consciously and carefully avoided. In other words, something has happened to the boy in the meantime; and this something is a poliferation and hardening and thickening of the tissues of the bottom of his feet. This hardening and thickening have been true reactions of the tissue to irritation; reactions, too, of a protective nature in that they have now brought about a condition that successfully resists irritation which a short time before would have produced local injury. So long as the boy wore shoes and there was no call upon the tissues for an unusually thick and resistant skin, the cells of the skin proliferated only to the extent that a lesser irritant laid demands upon them. The skin on the boy's feet was then what we would call normal under the conditions involved, that is, normal for a shoe-wearing boy. Yet all the time these same cells had an inherent capacity of increased proliferation and reaction to stimulus which, however, was not

brought into play until the proper irritant began to exert its force.

The puddler in an iron-mill, standing before his tremendously hot oven day after day and year after year, develops an unusual growth of hair on his chest-hair that serves not so much to keep him warm but to protect from excessive heat the area of skin that is continually exposed to the oven.

The term, hack-driver's face, or cab-driver's complexion, has passed into our descriptive language; and what it denotes is familiar to every one. It is the direct result of years of local exposure to extremes of heat and cold, of moisture and of wind. It is the culmination of innumerable reactions to irritation. For the hack-driver it acts as a protection in plying his trade. Abnormal for the debutante or office worker, it cannot be considered so for the teamster.

Instead of being applied over a large surface, irritation may be focussed on a point, when again tissues respond with renewed and over-vigorous growth and new anatomic structures develop. The common corn comes into being as the epithelium reacts at a point where the shoe rubs in a peculiar way. And the corn may cause great inconvenience because a tight shoe presses the hard tumor into the more tender and more sensitive structures beneath, yet the corn is undoubtedly the result of an effort of protection on the part of irritated tissues.

Milk is not the normal food of hens, and under ordinary circumstances the mucous membrane of the stomachs of hens does not therefore secrete rennin, a ferment which is necessary to the proper digestion of milk. But if we feed hens with milk we find that the stomach will pour out rennin; and this process then enters the category of reactions to the proper stimulation. It may also be looked upon as adaptive or protective in that its effect is the production of a material that promotes a more perfect digestion of an unusual food and thus assists in the general economy of the animal body.

We might multiply at great length examples similar to those we have just cited, and bring forward scores and hundreds of instances to illustrate how in response to irritation or stimulation (irritation or stimulation that is not part of the experience of universal man) the tissues react in a way that is locally adaptive or protective, or adaptive or protective to the extent that the best and most conservative purposes of the animal are served. Even though certain abnormalities of structure may thus result, so long as these enhance function, or at least so long as they do not impair function, we should be inclined to look upon them as entering into the more ordinary and even normal accompaniments of living matter. At least, we should not consider them as being in and of themselves diseased conditions, structurally abnormal though they be. would here emphasize that we must take a broader stand than one that conceives of every

And we

structural abnormality in terms of disease. It is surely the height of pedantry and foolishness to designate as a diseased condition that change from the anatomic norm the result of which is no inconvenience, discomfort or injury to its possessor, but which is exactly the opposite, namely, a protective and useful modification of the basic tissues of the species. The first few elephants with puny and stubby trunks, the first few cattle with abortive horns, the first few horses with hoofs, may have seemed abnormal, but the subsequent development of these species has shown that if these deviations from the anatomic rule did anything they contributed to the survival of the species in a way that worked against disease, death and decay. We shall see later that a reaction of tissues to irritation, which results in new and abnormal anatomic structure, may get out of bounds, may run wild as it were, and may produce a set of conditions that seriously hampers function and even threatens an animal's existence. Such abnormality then is really the basic cause of disease, and no mistake. But in and of itself anatomic change need not mean disease. If it did, then all our concepts of physical development and evolution go aglimmering.

The whole subject of tissue reactions to irritation is enormously broad and complex. In the field of medicine, we have in the first place, as we have just seen, adaptive or protective reactions that may result in structural changes which, while abnormal so far as the tissue norm of the species is concerned, work toward conserving and promoting the efficiency of the tissues and the individual. So long as they do this we cannot imagine that in the exact sense of the term disease exists even though abnormality is patent.

We have, in the second place, reactions which, once initiated, proceed in a disorderly manner and proceed to the point where tissue and even the life of the individual is destroyed. These pass the bounds of mere abnormality and sooner or later enter the category of disease. Of these, malignant tumors are the most striking examples.

We have, in the third place, another and very common type of reaction to irritation. This is pain, the purpose and end result of which may be conservative, yet the immediate effect of which may be disabling and therefore partake of the nature of disease. To the sufferer pain is the disease. But to the scientist pain is merely a guide that lights his way to the seat of disease. In the scheme of things pain undoubtedly accomplishes far more good than harm, even though the patient eloquently deny this. It frequently directs attention to an injured or diseased part and thus arouses the patient to the necessity of paying attention to the part. But a far more conservative and protective effect of pain is that it tends to limit the movement of an injured or diseased part, and thereby brings about a set of conditions that promotes healing. We find, therefore, that to a certain extent pain partakes of

As we contemplate the phenomena of animal life evidence crowds in from every side that resistance is a prime and fundamental attribute of tissues. If an animal would live it must resist resist the stresses, the injuries, the irritants to which it and its kind are continually throughout life exposed. Resistance thus becomes as important and necessary a property of living matter as are assimilation and reproduction. And it is accomplished by a variety of mechanisms, all of which involve at bottom the function of reaction to stimulus or irritation which we have just been discussing. Stresses, injuries and irritations are of many kinds. They include labor that involves unusually intense and prolonged muscular effort; blows and crushes and fractures and lacerations; excessive heat and cold; unusual dryness and moisture; intense stimulation of the passional or emotional life; the external and internal application of poisons; the accumulation of foreign matter such as dirt and dust on the surface and in the interior of the body and the transportation of such dirt and dust past the lining membranes into the tissues; the entrance into the tissues of living foreign particles such as bacteria which may or may not be endowed with parasitism, that is, with the power to propagate and maintain themselves in the living body. Every human being lives in an environment that embraces practically all such experiences; and to continue to live every human being must be able to resist them, and, if injury results, to more or less completely repair the damage.

If a tissue is wounded by a cut, one type of a very complicated reaction is immediately set in motion. The cut separates the area involved, an area that before was one smooth, unbroken surface, into two parts; or, as we say in more technical language, it brings about a solution of continuity. Now so far as the integrity of the body and its parts is concerned, it is of the utmost importance that there be nowhere a solution of continuity of tissue. Immediately following the injury, therefore, and because of the irritation that the tissues have received, there is released a series of processes that come into play with an orderliness and precision that cannot be duplicated by the most delicate and complicated piece of machinery, once the latter's pent-up energy is unleashed by opening the throttle. At a point where a moment before life was going on quietly and unobtrusively, the microscope now reveals a scene of bustle and excitement; and as we gaze on this tiny field of highly vitalized activity we are struck and

even awed by one outstanding fact, namely, that every single "effort" that the tissue is putting forth is directed to one ultimate end -to fill in and bridge the gap and to restore as nearly as possible its anatomic and functional integrity.

Blood vessels have been severed by the cut. So at once blood begins to flow from the wound; and as soon as the blood leaves the vessels and encounters the outside air it begins to undergo changes. It rapidly loses its fluid and free-flowing consistency. It begins to thicken, to coagulate and dry; and as coagulation is perfected it forms a firm plug that seals the open ends of the severed vessels, and temporarily fills in the gaping wound and protects what would be otherwise "raw" and tender edges from the harmful effects of outside irritation and the entrance of foreign particles. At the same time the tiny blood vessels in the immediate neighborhood of the wound, which have not been directly touched by the wounding instrument but which have been irritated by the injury that has occurred nearby, begin to exhibit new activities. They dilate and from them there exudes into the neighborhood of the wound some of the fluid serum of the blood and leucocytes and a few red blood cells. The dilated capillaries make the part red and hot, and the pouring out of materials from them brings about a certain amount of swelling, which in turn because of the tension and pressure it produces causes pain. Within hours, therefore, we have all the classical signs-rubor, calor, tumor and dolor-redness, heat, swelling and pain-which the ancient physicians comprehended under the wonderful tissue reaction that we recognize as inflammation. And with pain comes a certain disability of function, for the pain urges upon the patient a limitation of movement which by putting the affected part at rest promotes healing.

This very rough and imperfect description seeks to convey to the uninformed reader a simple picture of the early stages of the very complicated and "purposeful" tissue reaction that we know as inflammation. By the early filling in of the crevice of the wound with coagulated blood the immediately affected parts are afforded temporary protection. By the changes in the neighboring blood vessels and a consequent pouring out—exudation-of elements from these the injured part is localized and shut or walled off from surrounding healthy tissue. By the pain that follows hard upon the local changes the part is kept in comparative inactivity, and, ever in the patient's consciousness, is handled in such a manner as to avoid further injury.

But this description by no means completes the story of a simple inflammation. It has so far depicted only the early stages-the first steps that are characterized most prominently by changes in the blood vessels as a result of which there is an exudation of circulatory elements. We therefore call this the exudative (Continued on page 249)

I have often noticed how careful the specialist in tuberculosis is in what he says to his patient about the cure of tuberculosis. The fact is, he never says "cure." He says your case is "arrested, quiescent, or improved." You wonder why this is, and are oftimes disappointed when the doctor will go no further. But you should not be, because the more the doctor knows about the disease and human nature, the less he is going to commit himself as to a permanent cure.

On the other hand, your local doctor as a rule promises you too much. Now my idea, based upon a long and close observation, is that tuberculosis can be cured just as thoroughly as any other disease or wound, and that the lung will heal just as perfectly as an outside wound. When you once know how careless, how thoughtless, how foolhardy the average patient is when he is feeling well, after having done so many things he was told not to do. and finding that it didn't hurt him, you will then understand why it is the doctor will not tell you that you are cured.

The fact is the doctor tells you what is exactly right, and cannot afford to tell you otherwise for the simple reason that if you get it into your head that you are cured, you are almost certain to become lax in your habits and soon break down the second time.

Many will tell you that it is easier to break down the second time than the first. This is possibly true, for the reasoning is very plausible. Yet at the same time who knows? Were you not down and out the first time before you knew it? The fact is, outside of the soldier boys, no one else thinks about being examined for tuberculosis until he is down and out, or drifting to that end. Then how do you know that the second breakdown came about any easier than the first?

In the ordinary walks of life it is not what you do to-day or what you did yesterday that breaks you down. It is what you did many days, weeks, or perhaps months ago. I think my experience will prove to you that there are at least some cases that are just as hard to break down the second time as the first. Thirty odd years ago I lost a sister from tuberculosis. Up until that time no one in my section of the country had ever heard of a real cure for the disease, and when a person was found to have tuberculosis, it was a foregone conclusion that there was absolutely no hope for his recovery, but that he must at once make peace with his God, make his will and tell his friends where to bury him. There are many reasons why in those days no one recovered from a well-established case of tuberculosis. One of these reasons I shall take up a little later, for it is to-day one of the greatest enemies we

have to fight, and unless we conquer it there is still no hope for the present-day patient.

You may say that thirty years ago Dr. Trudeau had already demonstrated the rest and fresh-air treatment. Considering the actual year when Dr. Trudeau went to Saranac Lake you are right, but how far from Saranac Lake had this knowledge traveled even twenty-five years ago? Columbus discovered America in 1492, but just think how long it was afterward before a permanent colony was established on this continent. Less than twentyfive years ago the doctors in nearly every section of the United States advocated exercise in the open air as the cure of tuberculosis. Up until twenty-one years ago, to my certain knowledge, many doctors advocated the free use of whiskey. There came to my notice the case of one patient who was required to drink on an average not less than a pint of whiskey per day. Thanks to our good Lord, he didn't live very long to abuse himself with such "treatment."

We wonder now how any intelligent person I could have advocated either violent exercise or whiskey when it is so planily seen that either one will run the temperature and pulse up to a scarey height. But go back and see how long the pulse and temperature have been factors in the cure of tuberculosis and you will understand why the doctors overlooked these two important items.

Twelve years ago, or, to be more exact, on January 1st, 1907, I broke down. My local doctor thought my trouble was T. B., but, in order to be sure, he sent me to a specialist who gave me a thorough examination and without knowing what my own doctor thought, pronounced it tuberculosis. He said I was in bad shape and in a fair way to go all to pieces and advised me to go at once to Asheville, N. C., for six months and then camp six months in the mountains. After that he thought I would be able to do light work again. When I returned home I found a report from the State Board of Health on the specimen of sputum recently sent which showed not only positive, but tubercle bacilli very

numerous.

By the twelfth of January I had arranged my business so I could leave home for at least a short while. I went to Asheville and immediately put myself under the care of Dr. Minor, whose diagnosis verified that of the other doctors. The first week he gave me no exercise at all, but the second week he started me on a five minutes' walk. This seemed so very short to me that I selected my own kind of walking and went almost straight up the mountain to a nice sunny spot and lay down in the thick broom-sedge. I had made up